Coyote Blog

It is December, 2005.  The Gulf Coast had just been pounded, in succession, by Katrina, Rita, and Wilma.  Everyone was talking about how global warming seemed to be intensifying hurricanes.  In a speech just after Katrina, Al Gore said

 When the corpses of American citizens are floating in toxic floodwaters five days after a hurricane strikes, it is time not only to respond directly to the victims of the catastrophe but to hold the processes of our nation accountable, and the leaders of our nation accountable, for the failures that have taken place....

There are scientific warnings now of another onrushing catastrophe. We were warned of an imminent attack by Al Qaeda; we didn't respond. We were warned the levees would break in New Orleans; we didn't respond. Now, the scientific community is warning us that the average hurricane will continue to get stronger because of global warming. A scientist at MIT has published a study well before this tragedy showing that since the 1970s, hurricanes in both the Atlantic and the Pacific have increased in duration, and in intensity, by about 50 percent....

Two thousand scientists, in 100 countries, engaged in the most elaborate, well-organized scientific collaboration in the history of humankind, have produced long-since a consensus that we will face a string of terrible catastrophes unless we act to prepare ourselves and deal with the underlying causes of global warming....

At about the same time, the IPCC was in the process of preparing its fourth report, later released in 2007.  It said, in part:

Several peer-reviewed studies show a clear global trend toward increased intensity of the strongest hurricanes over the past two or three decades. The strongest trends are in the North Atlantic Ocean and the Indian Ocean. According to the 2007 Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC-AR4), it is “more likely than not” (better than even odds) that there is a human contribution to the observed trend of hurricane intensification since the 1970s. In the future, “it is likely [better than 2 to 1 odds] that future tropical cyclones (typhoons and hurricanes) will become more intense, with larger peak wind speeds and more heavy precipitation associated with ongoing increases of tropical [sea surface temperatures].”

So what happened?  Since Wilma in 2005, we have gone 6 full years without a category 3+ hurricane making landfall in the US, the longest span since 1900 without such an event.  And the clock is still counting.  When alarmists of all stripes were breathlessly predicting hurricane after hurricane in late 2005, the reality is that we wouldn't see another in the US for  over six years.

Of course, US landfall is in fact a terrible indicator of hurricane activity.  Its relevant to us, but it is a pretty random metric.  I said this when there were a lot of landfalls and I say it again since there have been so few.

A better metric is accumulated cyclonic energy, a sort of time integral of all large cyclonic storms worldwide.  Here is the most recent ACE figures:

As it turns out, the total strength of hurricane and hurricane-like storms has been falling almost since the exact day of Al Gore's speech in 2005 (another Gore effect!)  In fact, of late, it has hit numbers close to all-time lows.

Of course this chart will go back up some day, and then back down, and then up ... because hurricane activity has always been cyclical over decadal time scales.

The media loves to trumpet end-of-the-world predictions from folks like Al Gore and Paul Ehrlich, but they never go back five years later and back-check their predictions.  And despite their horrendous record for accuracy, the media eagerly publishes the next one.  Here is a proposed editorial rule for the MSM -- no breathless publication of anyone's next prediction without first revisiting the last one.

It is possible for the theory that the climate has a high sensitivity to CO2 (ie that a doubling of CO2 concentrations will lead to global temperature increases of 2.5C or higher) to be correct while still having ten years of flat to declining surface temperatures.  That is because Earth's great surface heat reservoir is the oceans, not the atmosphere, and so the extra heat from the greenhouse effect could be going into the oceans rather than into near-surface air.

However, it is NOT possible, as least as we (and by "we" I mean everyone, skeptics and alarmists alike) understand the climate, for CO2 to be holding a lot of extra heat and it not show up either in surface temperatures or ocean heat content.  The greenhouse effect does not turn off -- its effects may be masked in the chaotic weather systems, perhaps for years, but if the climate sensitivity to CO2 is really as high as the IPCC says, there has to be new heat going somewhere.

That is why a number of folks, including Roger Pielke, have argued for years that the best way to monitor whether we are truly seeing an additional forcing or heat input to the climate is to look at ocean heat content.  Understand, changes in ocean heat content would not tell us where the heat is coming from (e.g. anthropogenic CO2 vs. solar activity).  But it is pretty much impossible for us to imagine a new heat input to the Earth's surface, like greenhouse gas forcing from anthropogenic CO2, without observing its effect in ocean heat content.

I will turn over the story to Jo Nova, who has a good post on the new tools we have to measure ocean heat content since 2003.  In short, though, we have seen no rise in measured ocean heat content since we started measuring with technology dedicated to the task.  This means, if those who believe the climate has a high sensitivity to CO2 are right, something like 50,000 quintillion joules of energy have gone missing since 2003.  This is the "missing heat", and though climate scientists sometimes discuss it in private, they almost never do so in public.  Ocean heat is the dinosaur bone fossil that the creationists simply don't want to acknowledge.

Read the whole thing.  It is very simple and well-written and written.

PS- note in the chart above, the y-axis is mis-labelled a bit, it is not absolute heat content but changes in heat content from some base period.  Scientists call this the "anomaly."  This is typical of many climate charts.

here.

It's a wonder how, when over "97 percent to 98 percent" of scientific authorities accepted the Ptolomeic view of the solar system that we ever got past that.  Though I could certainly understand why in the current economy a die-hard Keynesian might be urging an appeal to authority rather than thinking for oneself.

When, by the way, did the children of the sixties not only lose, but reverse their anti-authoritarian streak?

Postscript:  I have always really hated the nose-counting approach to measuring the accuracy of a scientific hypothesis.  If we want to label something as anti-science, how about using straw polls of scientists as a substitute for fact-based arguments?

Yes indeed, the number of people in the newly made-up profession of "climate science" that are allowed by the UN control the content of the IPCC reports and whose funding is dependent on global warming being scary probably is very high.  The number of people in traditional scientific fields like physics, geology, chemistry, oceanography and meteorology who never-the-less study climate related topics that wholeheartedly are all-in for catastrophic man-made global warming theory would be very different

 Decide for yourself - see my video on global warming.  Am I anti-science?

My article this week at Forbes.com digs into some fundamental flaws of climate models

When I looked at historic temperature and CO2 levels, it was impossible for me to see how they could be in any way consistent with the high climate sensitivities that were coming out of the IPCC models.  Even if all past warming were attributed to CO2  (a heroic acertion in and of itself) the temperature increases we have seen in the past imply a climate sensitivity closer to 1 rather than 3 or 5 or even 10  (I show this analysis in more depth in this video).

My skepticism was increased when several skeptics pointed out a problem that should have been obvious.  The ten or twelve IPCC climate models all had very different climate sensitivities — how, if they have different climate sensitivities, do they all nearly exactly model past temperatures?  If each embodies a correct model of the climate, and each has a different climate sensitivity, only one (at most) should replicate observed data.  But they all do.  It is like someone saying she has ten clocks all showing a different time but asserting that all are correct (or worse, as the IPCC does, claiming that the average must be the right time).

The answer to this paradox came in a 2007 study by climate modeler Jeffrey Kiehl.  To understand his findings, we need to understand a bit of background on aerosols.  Aerosols are man-made pollutants, mainly combustion products, that are thought to have the effect of cooling the Earth’s climate.

What Kiehl demonstrated was that these aerosols are likely the answer to my old question about how models with high sensitivities are able to accurately model historic temperatures.  When simulating history, scientists add aerosols to their high-sensitivity models in sufficient quantities to cool them to match historic temperatures.  Then, since such aerosols are much easier to eliminate as combustion products than is CO2, they assume these aerosols go away in the future, allowing their models to produce enormous amounts of future warming.

Specifically, when he looked at the climate models used by the IPCC, Kiehl found they all used very different assumptions for aerosol cooling and, most significantly, he found that each of these varying assumptions were exactly what was required to combine with that model’s unique sensitivity assumptions to reproduce historical temperatures.  In my terminology, aerosol cooling was the plug variable.

Take all the psuedo-quasi-scientific stuff you read in the media about global warming.  Of all that mess, it turns out there is really only one scientific question that really matters on the topic of man-made global warming: Feedback.

While the climate models are complex, and the actual climate even, err, complexer, we can shortcut the reaction of global temperatures to CO2 to a single figure called climate sensitivity.  How many degrees of warming should the world expect for each doubling of CO2 concentrations  (the relationship is logarithmic, so that is why sensitivity is based on doublings, rather than absolute increases -- an increase of CO2 from 280 to 290 ppm should have a higher impact on temperatures than the increase from, say, 380 to 390 ppm).

The IPCC reached a climate sensitivity to CO2 of about 3C per doubling.  More popular (at least in the media) catastrophic forecasts range from 5C on up to about any number you can imagine, way past any range one might consider reasonable.

But here is the key fact -- Most folks, including the IPCC, believe the warming sensitivity from CO2 alone (before feedbacks) is around 1C or a bit higher (arch-alarmist Michael Mann did the research the IPCC relied on for this figure).  All the rest of the sensitivity between this 1C and 3C or 5C or whatever the forecast is comes from feedbacks (e.g. hotter weather melts ice, which causes less sunlight to be reflected, which warms the world more).  Feedbacks, by the way can be negative as well, acting to reduce the warming effect.  In fact, most feedbacks in our physical world are negative, but alarmist climate scientists tend to assume very high positive feedbacks.

What this means is that 70-80% or more of the warming in catastrophic warming forecasts comes from feedback, not CO2 acting alone.   If it turns out that feedbacks are not wildly positive, or even are negative, then the climate sensitivity is 1C or less, and we likely will see little warming over the next century due to man.

This means that the only really important question in the manmade global warming debate is the sign and magnitude of feedbacks.  And how much of this have you seen in the media?  About zero?  Nearly 100% of what you see in the media is not only so much bullshit (like whether global warming is causing the cold weather this year) but it is also irrelevant.  Entirely tangential to the core question.  Its all so much magician handwaving trying to hide what is going on, or in this case not going on, with the other hand.

To this end, Dr. Roy Spencer has a nice update.  Parts are a bit dense, but the first half explains this feedback question in layman's terms.  The second half shows some attempts to quantify feedback.  His message is basically that no one knows even the sign and much less the magnitude of feedback, but the empirical data we are starting to see (which has admitted flaws) points to negative rather than positive feedback, at least in the short term.  His analysis looks at the change in radiative heat transfer in and out of the earth as measured by satellites around transient peaks in ocean temperatures (oceans are the world's temperature flywheel -- most of the Earth's surface heat content is in the oceans).

Read it all, but this is an interesting note:

In fact, NO ONE HAS YET FOUND A WAY WITH OBSERVATIONAL DATA TO TEST CLIMATE MODEL SENSITIVITY. This means we have no idea which of the climate models projections are more likely to come true.

This dirty little secret of the climate modeling community is seldom mentioned outside the community. Don’t tell anyone I told you.

This is why climate researchers talk about probable ranges of climate sensitivity. Whatever that means!…there is no statistical probability involved with one-of-a-kind events like global warming!

There is HUGE uncertainty on this issue. And I will continue to contend that this uncertainty is a DIRECT RESULT of researchers not distinguishing between cause and effect when analyzing data.

If you find this topic interesting, I recommend my video and/or powerpoint presentation to you.

I am really just amazed by these remarks by NCAR's Dr. Ken Trenberth to be given, apparently planned for the American Meteorological Society gathering this month.   The and Anthony Watt has reprinted it on his blog.

It is hard to know where to start, but the following excerpt is an outstanding example of climate science process where 1.  Conclusions are assumed; 2.  Conclusions are deemed unequivocal by reference to authority; 3. Debate rules are proposed wherin it is impossible to refute the conclusion; 4.  All weather events that make the news are assumed to be caused or made worse by man-made warming, and thereby, in circular fashion, further prove the theory.

Now he has gone totally off the scientific reservation into astrology or the occult or something.   He is saying that there is a high probability that if CO2 levels were 120ppm lower that, for example, the floods in Pakistan would not have occurred.  This is pure conjecture, absolutely without facts, and probably bad conjecture at that.  After all, similar events of similar magnitude have occurred through all of recorded history in exactly these locations.

Some Notes

1.  For those unfamiliar with the issues, few skeptics deny that man's CO2 has no effect on warming, but believe the effect is being enormously exaggerated.  There is a bait and switch here, where the alarmist claims that "man is causing some warming" is the key conclusion, and once accepted, they can head off and start controlling the world's economy (and population, as seems to be desired by Trenberth).   But the fact that CO2 causes some greenhouse warming is a trivial conclusion.  The hard part is, in the complex climate system, how much does it cause.  There is a an argument to be made, as I have, that this warming is less than 1C over the next century.  This number actually has observational data on its side, as actual warming over the last century, given past CO2 increases, is much more consistent with my lower number than various alarmist forecasts of doom.  Again, this is discussed in much more depth here.

2.  One interesting fact is that alarmists have to deal with the lack of warming or increase in ocean heat content over the last 12 years or so.  They will argue that this is just a temporary aberration, and a much shorter time frame than they are working on.  But in effect, the core IPCC conclusions were really based on the warming over the 20 years from 1978-1998.  So while 12 years is admittedly short compared to many natural cycles in climate, and might be considered a dangerously short period to draw conclusions from, it is fairly large compared to the 20 year period that drove the IPCC conclusions.

Update: More thoughts from the Reference Frame.

News from the United Nations:

Robert Orr, UN under secretary general for planning, said the next Intergovernmental Panel on Climate Change report on global warming will be much worse than the last one.

Hmm, that kind of confirms what critics have been saying for years, that the IPCC has nothing to do with science.  Because, you see, to my knowledge the scientists of the next IPCC have not even started their work, but the UN leadership has already determined what the report will say.  Which is consistent with their process in the last go around, where the UN political guys crafted the management summary first, and then circulated it to the scientific teams with instructions to adjust their sections of the report to fit the pre-existing conclusion.

In the same article, we get more of the "accelerating" nonsense:

He said UN Secretary General Ban Ki-moon would make it clear to world leaders in Cancun "that we should not take any comfort in the climate deniers' siren call."

"The evidence shows us quite the opposite-- that we can't rest easy at all" as scientists agree that climate change "is happening in an accelerated way."

Its not even clear what the value of the first derivative is for climate change, or even if such a metric has any meaning in the complex climate system where regional trends can easily be going in opposite directions.  But anyone who can tell you that we know the second derivative, or even its sign, is totally full of crap.

Never (except perhaps with shark attack scares which come and go) have I seen such a classic case of observer bias.   Certain events occur in the tail ends of the normal distribution.  Suddenly everyone claims that these events are happening with more frequency, mainly because they get reported with more frequency. I reported on a great example of this from a supposedly scientific government report here, where researchers mistook improved measurement of certain events as a real underlying increase in the number of such events.  Another example here.

Of course, 95 percentile events can't be, by definition, happening more frequently.  The only thing that can happen is the normal distribution can have its standard deviation increase.  Similar to the second derivitive argument above, I am not a statistician, but my sense is that the odds that we could detect a standard deviation shift in the distribution of weather events using just a few years of highly imperfect data, even if such an underlying shift existed, is really  really low.

Cross-posted from Climate Skeptic

Over at my climate blog, I discuss the amazing similarity between Obama's claims for the effects of the stimulus and the IPCC's claims for the effects of CO2 on past temperatures.  Both seem to reach their results by assuming that all the other variables in a complex system (climate or the economy) can be isolated and assessed and coincidentally are exactly the value necessary to prove that the variable under study (CO2 or the stimulus) had exactly the effect the studies authors thought it would.

A kid and his dad manage to do the analysis that NASA, the EPA, the CRU, and the IPCC can't be convinced to perform.  Awesome.

I am sort of the anti-conspiracy theorist.  I have written a number of times that events people sometimes explain as orchestrated conspiracies often can be explained just as well by assuming that people with similar preferences and similar information and similar incentives will respond to these incentives in similar ways.

I think the great herd-think around climate alarmism is a good example, and the Bishop Hill blog brings us a specific illustration from the comment section of Watts Up With That.  A commenter observed that it was pretty hard to believe that thousands of scientists could be participating in a conspiracy.  Another commenter wrote back:

Actually not so hard.

Personal anecdote:
Last spring when I was shopping around for a new source of funding, after having my funding slashed to zero 15 days after going public with a finding about natural climate variations, I kept running into funding application instructions of the following variety:

Successful candidates will:
1) Demonstrate AGW [ed:  Anthropogenic Global Warming]
2) Demonstrate the catastrophic consequences of AGW.
3) Explore policy implications stemming from 1 & 2.

Follow the money "” perhaps a conspiracy is unnecessary where a carrot will suffice.

If only alarmist results are funded, then it should not be surprising that only alarmist studies are produced.

By the way, it is probably incorrect to think of climate science really being driven by 2500 scientists.  Here is an analogy:  Strategy at General Motors is in some sense driven by thousands of workers - salesmen who know the market, channel managers who know their distribution partners, planners who watch econometric trends, manufacturers who know what can and can't be done with costs, engineers who see what the next technological opportunities, etc. -- you get the idea.

But realistically, there are probably 20-25 people who are really setting and driving and communicating the corporate strategy for GM.  And those 20-25 people will likely say to the public that their strategy is supported by all those 200,000 workers.  But in fact there are thousands, maybe even a majority, that would say that they don't support the strategy and don't think that strategy is consistent with their bit of knowlege.

I think climate science works roughly the same way.  The same 20-25 people are lead authors on the IPCC, write key reports, contribute to Al Gore's movie, get quoted in the NY Times, run the Realclimate web site, and, of course, feature prominently in the CRU emails.  And while these 25 may claim thousands of scientists support their conclusions based on the mere fact that these other scientists contributed to an IPCC report that had these conclusions, many of these scientists, when actually asked, will disagree.

Here is one thing that is never mentioned -- most of the scientists outside of climate science who have gone on the record somewhere as supporting catastrophic man-made global warming theory, if you really talked to them, would say they made their statement in support of science, not global warming theory.  Most of these folks really haven't dug into the details, but the problem was presented to them as one of science vs. anti-science.  They are told by their peers and the media that AGW skeptics are all fundamentalist super right-wing anti-science evolution deniers who think the Earth is 4000 years old.

By saying they support AGW, these scientists are really trying to make the statement that they support science.  The bitter irony is that they are doing the opposite, enabling those in the core of the climate community who are trying to duck criticism and replication by demanding unquestioning respect for their authority.  The fact is that nearly every time one of these outsider scientists - a physicist or a geologist or a statistician, say - digs into the science, they are appalled at what they find and how bad the science behind catastrophic AGW theory really is.

The new Typepad editor is not at all ready for prime time.  I cannot find a single new feature in it, but it is rife with bugs.  Ones I have found so far:

• Certain images will not upload correctly into a post.  The Typepad folks do not know why
• Twice I had a crazy error when all of the text and buttons in the "add link" popup window suddenly were inserted into the post
• All my category setup was overwritten and I had to redo it all
• The spell checker is awful.  There is no "skip all" button.  I used "IPCC" 50+ times in one post at my other blog, and had to hit skip 50 times over and over
• The eliminated the blockquote editor option.  Good job on a blog editor!
• It is slow, slow, slow.

This is one of those enforced beta situations where all of use users are forced to do the beta testing they should have done.  This is the one downside to web-based applications, because there is no way I can do a rollback to the old version.

Update:  Also, publish is way slowed down.  Sometimes it take several minutes to be able to see new posts on my blog. This one still has not appeared after hitting shift-refresh now for 3 minutes.

Update #2:  They sent me an article to trumpet all the new features, but I could find not a single new feature listed.  And it is probably a bad sign they felt the need to put this up front in the article:

If you are seeing the new compose, please be aware that it is not a beta version, it's an upgraded editor that you should be seeing.

LOL

Update #3:  Getting good comments about WordPress.  I may have to check it out.

Happy Birthday Vladimer Lenin Earth Day.  I have a few thoughts for the day:

Sucking the Oxygen Out of the Environmental Movement

Observe today how little of the discussion is about anything other than climate.  There are still many environmental issues in the world that can be improved by the application of man's effort and technology -- unfortunately, climate is the least of these but the issue getting the most attention.  Consider how the global warming panic has sucked the oxygen out of the environmental movement.  Ten years from now, I predict that true environmentalists will be looking back on the hysteria over trace amounts of CO2 in the atmosphere as a huge setback for real environmental progress.

Environmentalism and Socialism

If you attend any Earth Day events today, notice how many of the speeches and presentations and such are anti-corporate, anti-trade, anti-capitalist, anti-wealth screeds, and have little to do with the environment.  If you actually go to a live Earth Day event, you will see why the selection of Lenin's birthday was no accident.  You will not see this on the network news, because the media is sympathetic to the environmental movement and tends to edit the socialist rants out as PR protection for the environmentalists, knowing that American audiences would lose sympathy for them if they listened to the whole package. (This is mostly an American phenomenon - I have found from my brief travels in Europe that the media there does less such editing, perhaps because they know their audience is more comfortable with socialism).

The Climate Denier Trick

There are a lot of reasons not to be worried about "inaction" on global warming.  To justify the enormously expensive cuts in CO2 productions, on the order of 80% as supported by Obama and Clinton, one has to believe every element of a five-step logic chain:

1. Mankind is increasing CO2 concentrations in the atmosphere
2. Increased atmospheric CO2 causes the world to warm (by some amount, large or small)
3. The increases in CO2 from man will cause substantial warming, large enough to be detectable above natural climate variations
4. The increases in world temperatures due to man's CO2 will have catastrophic impacts on civilization
5. These catastrophic impacts and their costs are larger than the enormous costs, in terms of poverty and lost wealth, from reducing CO2 with current technologies.

Climate alarmists have adopted a rhetorical trick that no one in the media seems willing to call them on.   They like to wage the debate over global warming policy on points one and two only, skipping over the rest.  Why?  Because the science behind numbers one and two are pretty strong.  Yes, there are a few folks who will battle them on these points, but even very strong skeptics like myself accept points one and two as proved. 

Here are some examples of how this trick works.  If, like me, you do not accept steps 3-4-5 in the above logic chain, you will be called a "denier."  When asked what a denier means, a climate alarmist will often position this denial as somehow disputing #1 and #2.  On the other hand, if one publicly accepts #1 and #2, the alarmist will shout "QED" and then proceed to say that strong action on CO2 is now justified.  When an alarmist says that the a consensus exists, he is probably correct on points 1 and 2.  But he is absolutely incorrect that a consensus exists on 3-4-5.

Don't believe me?  Think back to the early Republican debate, where the moderator asked for a show of hands whether [I can't remember the exact question] man was causing global warming.  The implication is that you either have to accept this whole logic chain or not.  One can see why Fred Thompson begged to have 90 seconds to explain his position, and why the moderator, presumably in the alarmist camp, denied it to him. 

Over the last year or two, skeptics have gotten a lot better at making their argument.  Most all of them, like I do, begin their arguments by laying out a logic chain like this and explaining why one can believe that man-made greenhouse gases cause warming without accepting the need for drastic climate action.  The result?  Alarmists have stopped debating, and/or have declared that the debate is "over."  Remember that last great Al Gore climate debate?  Neither do I.

The Single Best Reason Not To Be Worried About Climate

I could, and have, in my books and videos, made arguments on many points in 3-4-5 (links at the bottom of the post).  In four, no one ever considers the good effects of warming (e.g. on growing seasons and crop yields) and most every other problem is greatly exaggerated, from hurricane formation to sea level rises.  And in five, every time someone has tried to put a price on even small reductions in CO2, the numbers are so enormous that they are quickly suppressed by a environmentalist-sympathetic media.  Suffice it to say that even the climate-sanctimonious Europeans have not been willing to pay the price for even slowing down their CO2 growth (which has risen faster than in the US), much less reducing it.

But in this logic chain, there is little need to argue about four and five if #3 is wrong.  And it is.

The effects of CO2 acting alone on temperatures are quite small -- And everyone, even the alarmists, agree!  A doubling of CO2 concentrations, without other effects that we will discuss
in a moment, will heat the earth no more than about 1 degree Celsius (though several studies recently have argued the number is much less).  This is not some skeptic's hallucination -- this is
straight out of the IPCC third and fourth assessments [IPCC text quoted here].  In fact, the IPCC in their reports has steadily reduced their estimate of the direct contribution of CO2 on temperatures.  CO2, acting
alone, warms the Earth only slowly, and at this rate we would see less
than a degree of warming over the next century, more of a nuisance than
a catastrophe.

But some scientists do come up with catastrophic warming
forecasts.  They do so by assuming that our Earth's climate is
dominated by positive feedbacks that multiply the initial warming from
CO2 by a factor of three, four, five or more.  This is a key point -- the
catastrophe does not come from the science of greenhouse gases, but
from separate hypotheses that the earth's climate is dominated by
positive feedback. This is why saying that greenhouse gas
theory is "settled" is irrelevant to the argument about catastrophic
forecasts.  Because these positive feedbacks are NOT settled science.

In fact, the IPCC admits it does not even know the sign of
the most important effect (water vapor), much less its magnitude.  They
assume that the net effect is positive, and in fact strongly so - on the order of 60-80% feedback or more, nearly unprecedented numbers for a long-term stable physical system [more on feedback and its math here].  This is particularly ironic because alarmist Michael Mann, with his hockey stick, famously posited that temperatures over the last 1000 years were incredibly flat and stable until man started burning fossil fuels, a proposition that is hard to believe if the climate is dominated by strong positive feedback.   Note that when people like Al Gore say things like "tipping point," they are in effect hypothesizing that feedback is greater than 100%, meaning that climate can be a runaway process, like nuclear fission.

In fact, with the 100 or so years of measurements we have for temperature and CO2, empirical evidence does not support these high positive feedbacks.
Even if we assign all the 20th century warming to CO2, which is
unlikely, our current warming rates imply close to zero feedback.  If
there are other causes for measured 20th century warming other than
CO2, thereby reducing the warming we blame on CO2, then the last
century's experience implies negative rather than positive feedback in
the system.  As a result, it should not be surprising that high
feedback-driven forecasts from the 1990 IPCC reports have proven to be
way too high vs. actual experience (something the IPCC has since
admitted).

However, climate scientists are unwilling to back down from the thin
branch they have crawled out on.  Rather than reduce their feedback
assumptions to non-catastrophic levels, they currently hypothesize a
second man-made cooling effect that is masking all this feedback-driven
warming.  They claim now that man-made sulfate aerosols and black
carbon are cooling the earth, and when some day these pollutants are
reduced, we will see huge catch-up warming.  If anything, this cooling
effect is even less understood than feedback.  What we do know is that,
unlike CO2, the effects of these aerosols are short-lived and therefore
localized, making it unlikely they are providing sufficient masking to
make catastrophic forecasts viable.  I go into several reality checks
in my videos, but here is a quick one:  Nearly all the man-made cooling
aerosols are in the northern hemisphere, meaning that most all the
cooling effect should be there -- but the northern hemisphere has
actually exhibited most of the world's warming over the past 30 years,
while the south has hardly warmed at all.

In sum, to believe catastrophic warming forecasts, one has to believe both of the following:

1. The climate is dominated by strong positive feedback, despite
   our experience with other stable systems that says this is unlikely and
   despite our measurements over the last 100 years that have seen no such
   feedback levels.
2. Substantial warming, of 1C or more, is being masked by aerosols,
   despite the fact that aerosols really only have strong presence over
   5-10% of the globe and despite the fact that the cooler part of the
   world has been the one without the aerosols.

Here's what this means:  Man will cause, at most, about a degree of
warming over the next century.  Most of this warming will be
concentrated in raising minimum temperatures at night rather than
maximum daytime temperatures  (this is why, despite some measured
average warming, the US has not seen an increase of late in maximum
temperature records set).  There are many reasons to believe that man's
actual effect will be less than 1 degree, and that whatever effect we
do have will be lost in the natural cyclical variations the climate
experiences, but we are only just now starting to understand.

To keep this relatively short, I have left out all the numbers and
such.  To see the graphs and numbers and sources, check out my new climate video, or my longer original video, or download my book for free.

Update: Very relevant article by Roy Spencer on the over-estimation of feedback in climate models.

Many of us, especially those who were trained as meteorologists,
have long questioned the climate research community's reliance on
computerized climate models for global warming projections.  In
contrast to our perception that the real climate system is constantly
readjusting to internal fluctuations in ways that stabilize the system,
climate models built upon measured climate behavior invariably suggest
a climate system that is quite sensitive - sometimes catastrophically
sensitive "” to perturbations such as those from anthropogenic
greenhouse gas emissions.  Unfortunately, it has been difficult to
articulate our "˜hand-waving' concerns in ways that the modelers would
appreciate, i.e., through equations.   

After years of pondering this issue, and after working on our two
latest papers on feedbacks (Spencer et al., 2007; Spencer and Braswell,
2008, hereafter SB08), I believe that I can now explain the main reason
for this dichotomy.   Taking the example of clouds in the climate
system, the issue can be introduced in the form of a question:

To what extent are climatic variations in
clouds caused by temperature change (feedback), versus temperature
change being the result of cloud variations? 

Cross-posted from Climate Skeptic.  I believe this to be an extremely important issue.  Catastrophic global warming forecasts are driven not by greenhouse gas theory, but by the theory that the Earth's climate is dominated by positive feedback.  This post discusses these issues:

It is silly to argue whether CO2 in the atmosphere can cause global warming: It clearly does.  The issue is not "if" but "how much".  The warming from man's CO2 might be 8 degrees in a century, as Al Gore might argue, in which case man's CO2 would be incredibly disruptive.  Or it might cause just a few tenths of a degree of warming, which might be unnoticeable within the noise of natural climate variation.

Interestingly, the key to understanding this issue of the amount of warming does not actually lie in greenhouse gas theory.  Most scientists, skeptics and alarmists alike, peg the warming directly from CO2 at between 0.3 and 1.0 degrees Celsius for a doubling in CO2 levels  (this notion of how much temperatures would increase for a doubling of CO2 levels is called climate sensitivity).  If this greenhouse gas warming was the only phenomenon at work, we would expect man-made warming over the next century even using the most dire assumptions to be less than 1C, or about the same amount we have seen (non-catastrophically) over the last century.  Warming forecasts of this magnitude would not in any way, shape, or form justify the draconian economic impacts of many current government carbon reduction proposals.

The key, as I have written before (and here), lies not in greenhouse gas theory itself but in the theory that the earth's climate is dominated by positive feedback.  This theory hypothesizes that small changes in temperature from greenhouse gas increases would be multiplied 3,4,5 times or more by positive feedback effects, from changes in atmospheric water vapor to changing surface albedo.

Let me emphasize again:  The catastrophe results not from greenhouse gas theory, but from the theory of extreme climactic positive feedback.  In a large sense, all the debate in the media is about the wrong thing!  When was the last time you saw the words "positive feedback" in a media article about climate?

Christopher Monckton has an absolutely dead-on post at Roger Pielke's blog about this feedback theory that I want to excerpt in depth.

This chart is a good place to start.  It shows the changes in the IPCC's estimate for climate sensitivity to CO2 and how it has changed over the course of the reports.  More importantly, he splits the forecast between the amount due directly to Co2, and the amount due to the multiplicative effect of positive feedback.  The green bar is the direct contribution of Co2, and the pink is the feedback.

We can observe a couple of things.  First, the IPCC's estimate of the amount of warming due to CO2 directly via the greenhouse gas effect has actually been going down over time.  (Note that there are those, like Richard Lindzen, who suggest these numbers are still three times too high given that we have not observed a difference in surface and lower troposphere warming that greenhouse gas theory seems to predict).

Second, you will see that the IPCC's overall forecasts of climate sensitivity have been going up only because their estimates of positive feedback effects have gone way up.  The IPCC assumes that feedback effects multiply warming from CO2 by three.  And note that the IPCC's forecasts of feedback effects trail those of folks like James Hansen and Al Gore. 

So how confident are we in these feedback effects?  Well, it turns out we are not even sure of the sign!  As Monckton writes:

The feedback factor f accounts for at least two-thirds of all radiative forcing in IPCC (2007); yet it is not expressly quantified, and no "Level Of Scientific Understanding" is assigned either to f or to the two variables b and κ upon which it is dependent....

Indeed, in IPCC (2007) the stated values for the feedbacks that account for more than two-thirds of humankind's imagined effect on global temperatures are taken from a single paper. The value of the coefficient z in the CO₂ forcing equation likewise depends on only one paper. The implicit value of the crucial parameter κ depends upon only two papers, one of which had been written by a lead author of the chapter in question, and neither of which provides any theoretical or empirical justification for the IPCC's chosen value. The notion that the IPCC has drawn on thousands of published, peer-reviewed papers to support its central estimates for the variables from which climate sensitivity is calculated is not supported by the evidence.

Given the importance of feedback to their forecasts, the treatment in the latest IPCC report of feedback borders on the criminal.  I have read the relevant sections and it is nearly impossible to find any kind of discussion of these issues.  A cynical mind might describe the thousands of pages of the IPCC report as the magician grabbing your attention with his left hand to hide what is in his right hand.  And what is being hidden is that ... there is nothing there!  Feedback is the pivotal point on which the whole discussion of drastic carbon abatement should turn and there is nothing there. 

Monckton goes further, to point out that hidden in the IPCC numbers lies an absurdity:

if the upper estimates of each of the climate-relevant feedbacks listed in IPCC (2007) are summed, an instability arises. The maxima are -

Water vapor 1.98, lapse rate -0.58, surface albedo 0.34, cloud albedo 1.07, CO₂ 0.57, total 3.38 W m^-2 K^-1.

The equation f = (1 - bκ)^-1 becomes unstable as b → κ^-1 = 3.2 W m^-2 K^-1. Yet, if each of the individual feedbacks imagined by the IPCC is increased to less than the IPCC's maximum, an instability or "runaway greenhouse effect" is reached.

Yet it is reliably inferred from palaeoclimatological data that no "runaway greenhouse effect" has occurred in the half billion years since the Cambrian era, when atmospheric CO₂ concentration peaked at almost 20 times today's value

Positive feedback can be weird and unstable.  If there is enough of it, processes tend to run away (e.g. nuclear fission), which is what Monckton is arguing that some of the IPCC assumptions lead to.  Even when feedback is less positive, it still can cause processes to fluctuate wildly.  In fact, it is fairly unusual for long-term stable processes like climate to be dominated by positive feedback.  Most scientists, when then meet a new process, would probably assume negative feedback until proven otherwise.  This is a particular issue in climate, where folks like Michael Mann have gone out of their way to argue that the world temperature history over the last 1000 years before man began burning fossil fuels is incredibly stable and unchanging.  If so, how can this be consistent with strong positive feedback?

Anyway, there is a lot more numerical detail in Monckton's post if you want to dig into the equations.

I would add one thing to his analysis:  If you look at the last 100 years of history, the change in temperature given the observed change in CO2 levels comes no where close to a climate sensitivity of 3 or more, even when you assign all historical warming to CO2 rather than other effects like the sun.  In fact, as I showed in this analysis, climate sensitivity appears to be 1.2 when one assigns all past warming to CO2, and something well less than that if one accepts the sun and other effects also play a role.  These historical analyses would point to feedback that is either zero or negative rather than positive, more in line with what one would expect from complex natural systems.

You can see a discussion of many of these topics in the video below:

Via Climate Skeptic:

The catastrophe that Al Gore and others prophesy as a result of greenhouse
gases is actually not, even by their admission, a direct result of greenhouse
gas emissions.  Even the IPCC believes that warming directly resulting from
manmade CO2 emissions is on the order of 1 degree C for a doubling of CO2 levels
in the atmosphere (and many think it to be less). 

The catastrophe comes, not from a mere 1 degree of warming, but from the
multiplication for this warming 3,4,5 times or more by hypothesized positive
feedback effects in the climate.   Greenhouse gas theory gives us warming
numbers we might not even be able to find amidst the natural variations of our
climate;  it is the theory of strong positive climate feedback that gives us the
apocalypse.

So, In a large sense, the proposition that we face environmental armageddon
due to CO2 rests not on greenhouse gas theory, which is pretty well understood,
but on the theory that our climate system is dominated by strong positive
feedbacks.  This theory of positive feedback is almost never discussed publicly,
in part because it is far shakier and less understood than greenhouse gas
theory.  In fact, it is very probable that we have the sign, much less the magnitude,
of major feedback effects wrong.  But if we are considering legislation to gut
our economies in order to avoid a hypothesized climate catastrophe, we should be
spending a lot more time putting scrutiny on this theory of positive feedback,
rather than just greenhouse gas theory.

My son finished his science fair project to measure the Phoenix urban heat island, the effect the IPCC swears is too small to have an effect on surface temperature measurements.  See all his results at Climate Skeptic.

Over at Climate Skeptic, I discuss a Cato study that finally gets at an issue I have tried to press for years:  That even if one accepts the worst of the IPCC warming scenarios (which I do not) the
cost of CO2 abatement, particularly in terms of lost economic growth, is far
higher than the cost of rising temperatures -- ESPECIALLY for the poor. 

Hurricanes are a great example.  The world is probably warming a bit due to man's CO2, but likely less than the catastrophic rates one sees in the press.  This warming may or may not increase hurricane severity.  But let's assume it does.  Let's say Asia faces an extra cyclone or two each year from global warming. 

Over time, trends in deaths from hurricanes and severe deaths have shown no correlation with storm frequency or severity.  Death rates from storms track nearly perfectly with wealth:  As wealth has increased in the US, severe storm deaths have dropped to nearly zero;  Where countries are less wealthy, they experience more death.  Bangladesh is not the site of some of the deadliest storms on record because they get hit by the worst storms, but because they are poor.  (figure source)

As a result, if we really face this tradeoff (which I doubt) the world still is better off richer with 10 hurricanes than poorer with 8.

I began with an 85-page book.  I shortened that to a 50-minute film, and then a 9-minute film.  With that experience, I think I can now pull out and summarize in just a few paragraphs why we should not fear catastrophic global warming.  Here goes:

Climate catastrophists often argue that global warming theory is "settled science."  And they are right in one respect:  We have a pretty good understanding of how CO2 can act as a greenhouse gas and cause the earth to warm.  What is well agreed upon, but is not well communicated in the media, is that a doubling of CO2, without other effects that we will discuss in a moment, will heat the earth about 1 degree Celsius (plus or minus a few tenths).  This is not some skeptic's hallucination -- this is straight out of the IPCC third and fourth assessments.  CO2, acting alone, warms the Earth only slowly, and at this rate we would see less than a degree of warming over the next century, more of a nuisance than a catastrophe.

But some scientists do come up with catastrophic warming forecasts.  They do so by assuming that our Earth's climate is dominated by positive feedbacks that multiply the initial warming from CO2 by a factor of three, four, five or more.  This is a key point -- the catastrophe does not come from the science of greenhouse gases, but from separate hypotheses that the earth's climate is dominated by positive feedback.  This is why saying that greenhouse gas theory is "settled" is irrelevant to the
argument about catastrophic forecasts.  Because these positive feedbacks are NOT settled science.  In fact, the IPCC admits it does not even know the sign of the most important effect (water vapor), much less its magnitude.  They assume that the net effect is positive, but they are on very shaky ground doing so, particularly since having long-term stable systems like climate dominated by positive feedback is a highly improbable.

And, in fact, with the 100 or so years of measurements we have for temperature and CO2, empirical evidence does not support these high positive feedbacks.  Even if we assign all the 20th century warming to CO2, which is unlikely, our current warming rates imply close to zero feedback.  If there are other causes for measured 20th century warming other than CO2, thereby reducing the warming we blame on CO2, then the last century's experience implies negative rather than positive feedback in the system.  As a result, it should not be surprising that high feedback-driven forecasts from the 1990 IPCC reports have proven to be way too high vs. actual experience (something the IPCC has since admitted).

However, climate scientists are unwilling to back down from the thin branch they have crawled out on.  Rather than reduce their feedback assumptions to non-catastrophic levels, they currently hypothesize a second man-made cooling effect that is masking all this feedback-driven warming.  They claim now that man-made sulfate aerosols and black carbon are cooling the earth, and when some day these pollutants are reduced, we will see huge catch-up warming.  If anything, this cooling effect is even less understood than feedback.  What we do know is that, unlike CO2, the effects of these aerosols are short-lived and therefore localized, making it unlikely they are providing sufficient masking to make catastrophic forecasts viable.  I go into several reality checks in my videos, but here is a quick one:  Nearly all the man-made cooling aerosols are in the northern hemisphere, meaning that most all the cooling effect should be there -- but the northern hemisphere has actually exhibited most of the world's warming over the past 30 years, while the south has hardly warmed at all.

In sum, to believe catastrophic warming forecasts, one has to believe both of the following:

1. The climate is dominated by strong positive feedback, despite our experience with other stable systems that says this is unlikely and despite our measurements over the last 100 years that have seen no such feedback levels.
2. Substantial warming, of 1C or more, is being masked by aerosols, despite the fact that aerosols really only have strong presence over 5-10% of the globe and despite the fact that the cooler part of the world has been the one without the aerosols.

Here's what this means:  Man will cause, at most, about a degree of warming over the next century.  Most of this warming will be concentrated in raising minimum temperatures at night rather than maximum daytime temperatures  (this is why, despite some measured average warming, the US has not seen an increase of late in maximum temperature records set).  There are many reasons to believe that man's actual effect will be less than 1 degree, and that whatever effect we do have will be lost in the natural cyclical variations the climate experiences, but we are only just now starting to understand.

To keep this relatively short, I have left out all the numbers and such.  To see the graphs and numbers and sources, check out my new climate video, or my longer original video, or download my book for free.

Our (mostly free) society has survived many challenges.  But will it be able to withstand gentlemen like this waving around immensely flawed climate science:

Liberal democracy is sweet and addictive and indeed in the most
extreme case, the USA, unbridled individual liberty overwhelms many of
the collective needs of the citizens. The subject is almost sacrosanct
and those who indulge in criticism are labeled as Marxists, socialists,
fundamentalists and worse. These labels are used because alternatives
to democracy cannot be perceived! Support for Western democracy is
messianic as proselytised by a President leading a flawed democracy

There must be open minds to look critically at liberal democracy.
Reform must involve the adoption of structures to act quickly
regardless of some perceived liberties. ...

We are going to have to look how authoritarian decisions
based on consensus science can be implemented to contain greenhouse
emissions. It is not that we do not tolerate such decisions in the very
heart of our society, in wide range of enterprises from corporate
empires to emergency and intensive care units. If we do not act
urgently we may find we have chosen total liberty rather than life.

He has great admiration for how China does things

The [plastic shopping bag] ban in China will save importation and use of five million tons of
oil used in plastic bag manufacture, only a drop in the ocean of the
world oil well. But the importance in the decision lies in the fact
that China can do it by edict and close the factories. They don't have
to worry about loss of political donations or temporarily unemployed
workers. They have made a judgment that their action favours the needs
of Chinese society as a whole.

Don't say I didn't warn you.

By the way, here is a little "tip."  The author says this:

Unfortunately it seems increasingly likely that the IPCC underestimated
the speed of climate change and failed to recognise the likely effect
of a range of tipping points which may now be acting in concert.

I believe that man is having a warming effect on the earth, but that effect is small and non-catastrophic.  There are reasons I may be wrong.  BUT, you should immediately laugh out of the room anyone who talk about "a range of tipping points" in a system like the earth's climate that has been reasonably stable for tens of millions of years.  When used by climate catastrophists, the word "tipping point" means:  Yeah, we are kind of upset the world is not warming nearly as fast as our computer models say it should, so we will build an inflection point about 10 years out into the forecast where the slope of change really ramps up and we will call it a "tipping point" because, um, that is kindof a cool hip phrase right now and make us sound sophisticated and stuff.

Postscript:  Anyone who makes this statement is WELL grounded in reality:

All this suggests that the savvy Chinese rulers may be first out of the blocks to assuage greenhouse emissions

LOLOLOL.  They are building a new coal plant, what, every three days or so in China?

Postscript #2: Quiz for older folks out there:  How long ago was it that environmentalists were encouraging us to use plastic bags over paper because it saved a tree?

HT:  Tom Nelson

I am trying to keep most of my long climate posts off this site and over at Climate Skeptic.  However, I have cross-posted this one because it is a good example for laymen of just what crap gets put forward in the media today about global warming.  It demonstrates the gullibility of the media, the gross exaggerations that exist in nearly every climate catastrophe article, and, as an added bonus, demonstrates the scientific incompetence of the man who leads the UN, the organization that has taken onto itself the role of summarizing the state of climate science. 

OK, I understand that perhaps my worst flaw in trying to make a point is in being too loquacious.  In a previous post, I showed why estimates of climate catastrophe were overblown by using the earth's experience over the last 100 years as an empirical guide.  Today, I shall try to make the same point with fewer words and just two charts instead.

Scientists have a concept called climate sensitivity which refers to the amount of global warming in degrees Celsius we might expect from a doubling of CO2 concentrations from a pre-industrial 280ppm to 560ppm  (we are currently at about 380ppm today and will reach 560ppm between 2065 and 2100, depending on how aggressive a forecast you want to adopt).

A simple way to estimate sensitivity is from experience over the past century.  At the same time CO2 has gone up by 100ppm, global temperatures have gone up by at most 0.6 Celsius (from the 4th IPCC report).  I actually believe this number is over-stated due to uncorrected urban effects and other surface temperature measurement issues, but let's assume 0.6ºC.  Only a part of that 0.6ºC is due to man - some is likely do to natural cyclical effects, but again to avoid argument, let's assume man's CO2 has heated the earth 0.6 Celsius.  From these data points, we can project forward:

As you can see, the projection is actually a diminishing curve.  For reasons I will not go into again (you can read much more in my original post) this relationship HAS to be a diminishing curve.  It's a fact accepted by everyone.  True climate consensus.  We can argue about the slope and exact shape, but I have chosen midpoint values from a reasonable range.  The answer is not that sensitive to different assumptions anyway.  Even a linear extrapolation, which is clearly wrong scientifically, would only yield a sensitivity projection a few tenths of a degree higher.

What we arrive at is a sensitivity of about 1.2 degrees Celsius for a CO2 doubling (where the blue line crosses 560ppm).  In other words, we can expect another 0.6ºC increase over the next century, about the same amount we experienced (and most of us failed to notice) over the last century.

But, you are saying, global warming catastrophists get so much higher numbers.  Yes they do, with warming as high as 9-10C in the next century.  In fact, most global warming catastrophists believe the climate sensitivity is at least 3ºC per doubling, and many use estimates as high as 5ºC or 6ºC.  Do these numbers make sense?  Well, let's draw the same curve for a sensitivity of 3ºC, the low end of the catastrophists' estimates, this time in red:

To get a sensitivity of 3.0ºC, one has to assume that global warming due solely to man's CO2 (nothing else) would have to be 1.5ºC to date (where the red line intersects the current concentration of 380ppm).  But no one, not the IPCC or anyone else, believes measured past warming has been anywhere near this high.  So to believe the catastrophic man-made global warming case, you have to accept a sensitivity three or more times higher than historical empirical data would support.  Rather than fighting against climate consensus, which is how we are so often portrayed, skeptics in fact have history and empirical data on our side.  For me, this second chart is the smoking gun of climate skepticism.  We have a lot of other issues -- measurement biases, problems with historical reconstructions, role of the sun, etc -- but this chart highlights the central problem -- that catastrophic warming forecasts make no sense based on the last 100+ years of actual data.

Global warming catastrophists in fact have to argue against historical data, and say it is flawed in two ways:  First, they argue there are positive feedbacks in climate that will take hold in the future and accelerate warming; and second, they argue there are other anthropogenic effects, specifically sulphate aerosols, that are masking man-made warming.  Rather than just repeat myself (and in the interest in proving I can actually be succinct) I will point you to my original post, the second half of which deals in depth with these two issues. 

As always, you can find my Layman's Guide to Skepticism about Man-made Global Warming here.  It is available for free in HTML or pdf download, or you can order the printed book that I sell at cost.  My other recent posts about climate are here.

I know I have deluged you with a lot of climate change posts of late.  I think this particular post is important, as it is the clearest single argument I can make as to why I am skeptical that man-made global warming will rise to catastrophic levels.  It is not comprehensive, it took me 80 pages to do that, but it should get anyone thinking.

It turns out to be quite easy to do a simple but fairly robust reality check of global warming forecasts, even without knowing what a "Watt" or a "forcing" is.   Our approach will be entirely empirical, based on the last 100 years of climate history.  I am sensitive that we skeptics not fall into the
9/11 Truther syndrome of arguing against a coherent theory from
isolated anomalies.  To this end, my approach here is holistic and not
anomaly driven.  What we will find is that, extrapolating from history, it is almost impossible to get warming numbers as high as those quoted by global warming alarmists.

Climate Sensitivity

The one simple concept you need to understand is "climate sensitivity."  As used in most global warming literature, climate sensitivity is the amount of global warming that results from a doubling in atmospheric CO2 concentrations.   Usually, when this number is presented, it refers to the warming from a doubling of CO2 concentrations since the beginning of the industrial revolution.  The pre-industrial concentration is generally accepted as 280ppm (0.028% of the atmosphere) and the number today is about 380ppm, so a doubling would be to 560ppm.

As a useful, though not required, first step before we begin, I encourage you to read the RealClimate simple "proof" for laymen that the climate sensitivity is 3ºC, meaning the world will warm 3 degrees C with a doubling of CO2 concentrations from their pre-industrial level.  Don't worry if you don't understand the whole description, we are going to do it a different, and I think more compelling, way (climate scientists are a bit like the Wizard of Oz -- they are afraid if they make things too simple someone might doubt they are a real wizard).  3ºC is a common number for sensitivity used by global warming hawks, though it is actually at the low end of the range that the UN IPCC arrived at in their fourth report.  The IPCC (4th report, page 798) said that the expected value is between 3ºC and 4ºC and that there was a greater chance the sensitivity was larger than 6ºC than that it was 1.5ºC or less.  I will show you why I think it is extraordinarily unlikely that the number is greater even than 1.5ºC.

Our Approach

We are going to derive the sensitivity (actually a reasonable range for sensitivity) for ourselves in three steps.  First, we will do it a simple way.  Then, we will do it a slightly harder but more accurate way.  And third, we will see what we would have to assume to get a number anywhere near 3ºC.  Our approach will be entirely empirical, using past changes in CO2 and temperature to estimate sensitivity.  After all, we have measured CO2 going up by about 100 ppm.  That is about 36% of the way towards a doubling from 280 to 560.  And, we have measured temperatures -- and though there are a lot of biases in these temperature measurements, these measurements certainly are better than our guesses, say, of temperatures in the last ice age.  Did you notice something odd, by the way, in the RealClimate derivation?  They never mentioned measured sensitivities in the last 100 years -- they jumped all the way back to the last ice age.  I wonder if there is a reason for that?

A First Approximation

OK, let's do the obvious.  If we have experienced 36% of a doubling, then we should be able to take the historic temperature rise from CO2 for the same period and multiply it by 2.8 (that's just reciprocal of 36%) and derive the temperature increase we would expect for a full doubling.

The problem is that we don't know the historic temperature rise solely form CO2.  But we do know how to bound it.  The IPCC and most global warming hawks place the warming since 1900 at about 0.6ºC.  Since no one attributes warming before 1900 to man-made CO2  (it did warm, but this is attributed to natural cyclical recovery from the little ice age) then the maximum historic man-made warming is 0.6ºC.  In fact, all of that warming is probably not from CO2.  Some probably is from continued cyclical warming out of the little ice age.  Some, I believe strongly, is due to still uncorrected biases, particularly of urban heat islands, in surface temperature data. 

But let's for a moment attribute, unrealistically, all of this 0.6ºC to man-made CO2 (this is in fact what the IPCC does in their report).   This should place an upper bound on the sensitivity number.  Taking 0.6ºC times 2.8 yields an estimated  climate sensitivity of  1.7ºC.  Oops.  This is about half of the RealClimate number or the IPCC number! And if we take a more realistic number for man-made historic warming as 0.4ºC, then we get a sensitivity of 1.1ºC.  Wow, that's a lot lower! We must be missing something important!  It turns out that we are, in this simple analysis, missing something important.  But taking it into account is going to push our sensitivity number even lower.

A Better Approximation

What we are missing is that the relation between CO2 concentration and warming is not linear, as implied in our first approximation.  It is a diminishing return.  This means that the first 50 ppm rise in CO2 concentrations causes more warming than the next 50 ppm, etc.  This effect has often been compared to painting a window.  The first coat of paint blocks out a lot of light, but the window is still translucent.  The next coat blocks out more light, but not as much as the first.  Eventually, subsequent coats have no effect because all the light is already blocked.  CO2 has a similar effect on warming.  It only absorbs certain wavelengths of radiation returning to space from earth.  Once the absorption of those wavelengths is saturated, extra CO2 will do almost nothing. (update:  By the way, this is not some skeptic's fantasy -- everyone in climate accepts this fact).

So what does this mean in English?  Well, in our first approximation, we assumed that 36% of a CO2 doubling would yield 36% of the temperature we would get in a doubling.  But in reality, since the relationship is a diminishing return, the first 36% of a CO2 doubling will yield MORE than 36% of the temperature increase you get for a doubling.  The temperature increase is front-loaded, and diminishes going forward.   An illustration is below, with the linear extrapolation in red and the more realistic decreasing exponential extrapolation in blue.

The exact shape and equation of this curve is not really known, but we can establish a reasonable range of potential values.  For any reasonable shapes of this curve, 36% of a CO2 doubling (where we are today) equates to from 43% to 63% of the final temperature increase over a doubling.  This would imply that a multiplier between 2.3 and 1.6 for temperature extrapolation  (vs. 2.8 derived above for the straight linear extrapolation above) or a climate sensitivity of 1.4ºC to 1.0ºC if man-made historic warming was 0.6ºC and a range of 0.9ºC to 0.6ºC for a man-made historic warming of 0.4ºC.  I tend to use the middle of this range, with a multiplier of about 1.9 and a man-made historic warming of 0.5ºC to give a expected sensitivity of 0.95ºC, which we can round to 1ºC. 

This is why you will often hear skeptics cite numbers closer to 1ºC rather than 3ºC for the climate sensitivity.   Any reasonable analysis of actual climate experience over the last 100 years yields a sensitivity much closer to 1ºC than 3ºC.  Most studies conducted before the current infatuation with showing cataclysmic warming forecasts came up with this same 1ºC, and peer-reviewed work is still coming up with this same number. 

So what does this mean for the future?  Well, to predict actual temperature increases from this sensitivity, we would have to first create a CO2 production forecast and, you guessed it, global warming hawks have exaggerated that as well.  The IPCC says we will hit the full doubling to 560ppm around 2065 (Al Gore, incredibly, says we will hit it in the next two decades).  This means that with about 0.5C behind us, and a 3 sensitivity, we can expect 2.5C more warming in the next 60 years.  Multiply that times exaggerated negative effects of warming, and you get instant crisis.

However, since actual CO2 production is already below IPCC forecasts, we might take a more reasonable date of 2080-2100 for a doubling to 560.  And, combining this with our derived sensitivity of 1ºC (rather than RealClimate's 3ºC) we will get 0.5C more warming in the next 75-100 years.  This is about the magnitude of warming we experienced in the last century, and most of us did not even notice.

I know you are scratching you head and wondering what trick I pulled to get numbers so much less than the scientific "consensus."  But there is no trick, all my numbers are empirical and right out of the IPCC reports.  In fact, due to measurement biases and other climate effects that drive warming, I actually think the historic warming from CO2 and thus the sensitivity is even lower, but I didn't want to confuse the message. 

So what are climate change hawks assuming that I have not included?  Well, it turns out they add on two things, neither of which has much empirical evidence behind it.  It is in fact the climate hawks, not the skeptics, that need to argue for a couple of anomalies to try to make their case.

Is Climate Dominated by Positive Feedback?

Many climate scientists argue that there are positive feedbacks in the climate system that tend to magnify and amplify the warming from CO2.  For example, a positive feedback might be that hotter climate melts sea ice and glaciers, which reduces the reflectiveness of the earth's surface, which causes more sunlight to be absorbed, which warms things further.  A negative feedback might be that warmer climate vaporizes more water which forms more clouds which blocks sunlight and cools the earth. 

Climate scientists who are strong proponents of catastrophic man-made warming theory assume that the climate is dominated by positive feedbacks.  In fact, my reading of the IPCC report says that the climate "consensus" is that net feedback in the climate system is positive and tends to add 2 more degrees of temperature for every one added from CO2.  You might be thinking - aha - I see how they got a sensitivity of 3ºC:  Your 1ºC plus 2ºC in feedback equals 3ºC. 

But there is a problem with that.  In fact, there are three problems with this.  Here they are:

1. We came up with our 1ºC sensitivity empirically.  In other words, we observed a 100ppm past CO2 increase leading to 0.5ºC measured temperature increase which implies 1ºC sensitivity.  But since this is empirical, rather than developed from some set of forcings and computer models, then it should already be net of all feedbacks.  If there are positive feedbacks in the system, then they have been operating and should be part of that 1ºC.
2. There is no good scientific evidence that there is a large net positive feedback loop in climate, or even that the feedback is net positive at all.  There are various studies, hypotheses, models, etc., but no proof at all.  In fact, you can guess this from our empirical data.  History implies that there can't be any large positive feedbacks in the system or else we would have observed higher temperatures historically.  In fact, we can go back in to the distant historical record (in fact, Al Gore showed the chart I am thinking of in An Inconvenient Truth) and find that temperatures have never run away or exhibited any sort of tipping point effect.
3. The notion that a system like climate, which has been reasonably stable for millions of years, is dominated by positive feedback should offend the intuition of any scientist.  Nature is dominated in large part by negative feedback processes.  Positive feedback processes are highly unstable, and tend to run away to a distant endpoint.  Nuclear fission, for example, is a positive feedback process

Do aerosols and dimming imply a higher sensitivity?

Finally, the last argument that climate hawks would employ is that anthropogenic effects, specifically emission of SO2 aerosols and carbon black, have been reflecting sunlight and offsetting the global warming effect.  But, they caution, once we eliminate these pollutants, which we have done in the West (only to be offset in China and Asia) temperatures will no longer be suppressed and we will see the full extent of warming.

First, again, no one really has any clue the magnitude of this effect, or even if it is an effect at all.  Second, its reach will tend to be localized over industrial areas (since their presence in the atmosphere is relatively short-lived), whereas CO2 acts worldwide.  If these aerosols and carbon black are concentrated say over 20% of the land surface of the world, this means they are only affecting the temperature over 5% of the total earth' s surface.  So its hard to argue they are that significant.

However, let's say for a moment this effect does exist.  How large would it have to be to argue that a 3.0ºC climate sensitivity is justified by historical data?  Well, taking 3.0ºC and dividing by our derived extrapolation multiplier of 1.9, we get required historic warming due to man's efforts of 1.6ºC.  This means that even if all past 0.6ºC of warming is due to man (a stretch), then aerosols must be suppressing a full 1ºC of warming.   I can't say this is impossible, but it is highly unlikely and certainly absolutely no empirical evidence exists to support any number like this. Particularly since dimming effects probably are localized, you would need as much as 20ºC suppression in these local areas to get a 1ºC global effect.  Not very likely.

Why the number might even be less

Remember that when we calculated sensitivity, we needed the historical warming due to man's CO2.  A simple equation for arriving at this number is:

Warming due to Man's CO2 = Total Historic Measured Warming - Measurement Biases - Warming from other Sources + Warming suppressed by Aerosols

This is why most skeptics care if surface temperature measurements are biased upwards or if the sun is increasing in intensity.  Global warming advocates scoff and say that these effects don't undermine greenhouse gas theory.  And they don't.  I accept greenhouse gases cause some warming.  BUT, the more surface temperature measurements are biased upwards and the more warming is being driven by non-anthropogenic sources, the less that is being caused by man.  And, as you have seen in this post, the less warming caused by man historically means less that we will see in the future.  And while global warming hawks want to paint skeptics as "deniers", we skeptics want to argue the much more interesting question "Yes, but how much is the world warming, and does this amount of warming really justify the costs of abatement, which are enormous."

As always, you can find my Layman's Guide to Skepticism about Man-made Global Warming here.  It is available for free in HTML or pdf download, or you can order the printed book that I sell at cost.  My other recent posts about climate are here.

OK, I lied.  I have one more post I want to make on global warming now that Steve McIntyre's site is back up.  I suspect I tend to bury the lede in my warming posts, because I try to be really careful to set up the conclusion in a fact-based way.  However, for this post, I will try a different approach.  Steven McIntyre has reshuffled the data in a study on urbanization and temperature that is relied on by the last IPCC report to get this chart for US Temperature data.

Conclusion?  For this particular set of US temperature data, all the 20th century warming was observed in urban areas, and none was observed in rural areas less affected by urban heat islands, asphalt, cars, air conditioning, etc.

If it can be generalized, this is an amazing conclusion -- it would imply that the sum of US measured warming over the last century could be almost 100% attributed to urban heat islands (a different and more localized effect than CO2 greenhouse gas warming).  Perhaps more importantly, outside of the US nearly all of the historical temperature measurement is in urban areas -- no one has 100 year temperature records for the Chinese countryside.  However much this effect might be over-stating US temperature increases, it would probably be even more pronounced in measurements in other parts of the word.

OK, so how did he get this chart?  Did he cherry-pick the data?  First, a bit of background.

The 2003 Peterson study on urban effects on temperature was adopted as a key study for the last IPCC climate report.  In that report, Peterson concluded:

Contrary to generally accepted wisdom, no statistically significant
impact of urbanization could be found in annual temperatures.

This study (which runs counter to both common sense and the preponderance of past studies) was latched onto by the IPCC to allow them to ignore urban heat island effects on historical temperatures and claim that most all past warming in the last half-century was due to CO2.  Peterson's methodology was to take a list of several hundred US temperature stations (how he picked these is unclear, they are a mix of USHCN and non-USHCN sites) and divide them between "urban" and "rural" using various inputs, including satellite photos of night lights.  Then he compared the temperature changes over the last century for the two groups, and declared them substantially identical.

However, McIntyre found a number of problems with his analysis.  First, looking at Peterson's data set, he saw that the raw temperature measurement did show an urbanization effect of about 0.7C over the last century, a very large number.  It turns out that Peterson never showed these raw numbers in his study, only the numbers after he applied layers of "corrections" to them, many of which appear to McIntyre to be statistically dubious.  I discussed the weakness of this whole "adjustment" issue here.

Further, though, McIntyre found obviously rural sites lurking in the urban data, and vice versa, such that Peterson was really comparing a mixed bag with a mixed bag.  For example, Snoqualmie Falls showed as urban -- I have been to Snoqualmie Falls several times, and while it is fairly close to Seattle, it is not urban.  So McIntyre did a simple sort.  He took from Peterson's urban data set only large cities, which he defined as having a major league sports franchise  (yes, a bit arbitrary, but not bad).  He then compared this narrower urban data set from Peterson against Peterson's rural set and got the chart above.  The chart is entirely from Peterson's data set, with no cherry-picking except to clean up the urban list.

Postscript:  Please don't get carried away.  Satellite measurement of the troposphere, which are fairly immune to these urbanization effects, show the world has been warming, though far less than the amount shown in surface temperature databases.

Update: To reinforce the point about global sites, Brazil apparently only has six (6) sites in the worldwide database.  That is about 1/200 of the number of sites in the continental US, which has about the same land area.  And of those six, McIntyre compares urban vs. rural sites.  Guess what he finds?  And, as a follow up from the postscript, while satellites show the Northern Hemisphere is warming, it shows that the Southern Hemisphere is not.

We all know why Newsweek and many others (like Kevin Drum) choose to use the term "denier" for those of us who are skeptical of catastrophic anthropogenic global warming:  These media folks, who are hesitant to use the word "terrorist" because of its emotional content, want to imply that we skeptics are somehow similar to Holocaust deniers.

But beyond just the issues of false emotional content, the word denier is incorrect as applied to most skeptics, including myself, and helps man-made warming hawks avoid a difficult argument.  I try to be careful to say that I am a skeptic of "catastrophic man-made (or anthropogenic) global warming theory." 

• So, does that mean I think the world is not warming?  In fact, the evidence is pretty clear that it is warming (though perhaps not by as much as shown in current surface temperature databases).
• So does this mean that I think that human activities are not causing some warming?  In fact, I do think man-made CO2 is causing some, but not all the current 20th century warming trend.  I also think that man's land use  (urbanization, irrigated agriculture, etc) has effects on climate.

Where I really get skeptical is the next proposition -- that man's burning of fossil fuels is going to cause warming in the next century that will carry catastrophic impacts, and that these negative effects will justify massive current spending and government interventions (that will have their own negative consequences in terms of lost economic growth, increased poverty, and reduction in freedoms). 

Strong supporters of catastrophic man-made global warming theory do not usually want to argue this last point.  It is much easier to argue points 1 and 2, because the science is pretty good that the earth has warmed (though the magnitude is in question) and that CO2 greenhouse effect does cause warming (though the magnitude is in question).  That is why skeptics are called deniers.  It is in effect a straw man that allows greenhouse supporters to stay on 1 and 2 without getting into the real meat of the question.

Here is a quick example to prove my point.  Follow me for three paragraphs, then ask yourself if you have ever heard any of this in the media or on any RealClimate-type site's FAQ.

Anthropogenic global warming hawks admit that the warming solely from the CO2 greenhouse effect will likely NOT rise to catastrophic levels.  So how do they get such big, scary forecasts?  The answer is positive feedback.

Almost every process you can think of in nature operates by negative
feedback, meaning that an input to a system is damped.  Roll a ball, and eventually friction and wind resistance
bring
it to a stop.    Positive feedback means that an input to the system is multiplied and increased.  Negative feedback is a ball in the bottom of a bowl, always returning to the center; positive feedback is a ball perched precariously at the top of a
mountain that will run faster and faster downhill with a tiny push. Positive feedback
breeds instability, and processes that operate by positive feedback are
dangerous, and usually end up in extreme states -- these processes tend
to
"run away" like the ball rolling down the hill.  Nuclear fission, for
example, is a positive feedback process. 

Current catastrophic man-made global warming theory asserts that our climate is dominated
by positive feedback.  The last UN IPCC report posits that a small increase in
temperature from CO2 is multiplied 2,3,4 times or more by positive
feedbacks like humidity and ice albedo.   So a modest degree or degree and a half of warming from the greenhouse effect becomes a scary five or eight degrees of warming in the next century once any number of hypothesized positive feedbacks are applied.  Add to this exaggerated, sometimes over-the-top visions of possible negative consequences, and that is how global warming hawks justify massive government action.

OK, that is a very brief description of what I consider a sophisticated reason to be skeptical:  Most catastrophic warming forecasts depend on positive feedback loops, feedbacks for which we have little or no evidence and which don't tend to dominate in other stable systems.  So how many times have you seen this issue discussed?  Zero?  Yeah, its so much easier just to call us deniers.

If you are interested, here is slightly longer version of my skeptic's point of view.  Here is my much longer version.  Here is the specific chapter that discusses feedback loops.  Here is Roy Spencer discussing problems with studies trying to measure these feedbacks.

Postscript:  By the way, it is in this context that the discussions about restating temperatures and problems with historical surface temperature measurements are important.  Exaggerated historical warming numbers leave more room to posit positive feedback loops.  Lower historical numbers, or evidence past warming is driven by non-man-made sources (e.g. solar activity), leave less room to justify positive feedback loops.

Update:  RealClimate has posted their six steps to explain catastrophic warming from CO2.  Seems have buried the feedback issue.  Note that forcings mentioned here include feedbacks, they are not from CO2 alone but from CO2 + positive feedback.  Strange they didn't mention this.

On several occasions, I have discussed how much of the reported temperature increases worldwide in the last century are actually the results of adjustments to the actual gauge measurements.  These upward adjustments in the numbers by climate scientists actually dwarf measured increases.

Thanks to reader Scott Brooks, here is another such example except this time with measurement of sea level increases.  Dr. Nils-Axel Morner is the head of the Paleogeophysics and Geodynamics department at Stockholm University in Sweden.  He has studied sea-level changes for 35 years (emphasis added).

Another
way of looking at what is going on is the tide gauge. Tide gauging is
very complicated, because it gives different answers for wherever you
are in the world. But we have to rely on geology when we interpret it.
So, for example, those people in the IPCC [Intergovernmental Panel on
Climate Change], choose Hong Kong, which has six tide gauges, and they
choose the record of one, which gives 2.3 mm per year rise of sea
level. Every geologist knows that that is a subsiding area. It's the
compaction of sediment; it is the only record which you shouldn't use.
And if that figure [for sea level rise] is correct, then Holland would not be subsiding, it
would be uplifting.

And
that is just ridiculous. Not even ignorance could be responsible for a
thing like that. So tide gauges, you have to treat very, very
carefully. Now, back to satellite altimetry, which shows the water, not
just the coasts, but in the whole of the ocean. And you measure it by
satellite. From 1992 to 2002, [the graph of the sea level] was a
straight line, variability along a straight line, but absolutely no
trend whatsoever. We could see those spikes: a very rapid rise, but
then in half a year, they fall back again. But absolutely no trend, and
to have a sea-level rise, you need a trend.

Then,
in 2003, the same data set, which in their [IPCC's] publications, in
their website, was a straight line suddenly it changed, and showed a
very strong line of uplift, 2.3 mm per year, the same as from the tide
gauge. And that didn't look so nice. It looked as though they had
recorded something; but they hadn't recorded anything. It was the
original one which they had suddenly twisted up, because they entered a correction factor, which they took from the tide gauge. So it was not
a measured thing, but a figure introduced from outside. I accused them
of this at the Academy of Sciences in Moscow I said you have
introduced factors from outside; it's not a measurement. It looks like
it is measured from the satellite, but you don't say what really
happened. And they ans-wered, that we had to do it, because otherwise
we would not have gotten any trend!

That
is terrible! As a matter of fact, it is a falsification of the data
set. Why? Because they know the answer. And there you come to the
point: They know the answer; the rest of us, we are searching for the
answer. Because we are field geologists; they are computer scientists.
So all this talk that sea level is rising, this stems from the computer
modeling, not from observations. The observations don't find it!

I have
been the expert reviewer for the IPCC, both in 2000 and last year. The
first time I read it, I was exceptionally surprised. First of all, it
had 22 authors, but none of them  none were sea-level specialists. They
were given this mission, because they promised to answer the right
thing. Again, it was a computer issue. This is the typical thing: The meteorological community works with computers, simple computers.

Geologists
don't do that! We go out in the field and observe, and then we can try
to make a model with computerization; but it's not the first thing.

I am working on my next version of a layman's guide to skeptics arguments against catastrophic man-made global warming, which you can find here.