Coyote Blog

The table of contents for the rest of this paper, . 4A Layman's Guide to Anthropogenic Global Warming (AGW) is here.  Free pdf of this Climate Skepticism paper is here and print version is sold at cost here

Solar Irradiance

If you walked into a room and found that it was too hot,
would you, as a first step:

1. Measure the air to find anomalies in the mix of gasses
2. Count the number of people in the room, to assess the effect
        of body heat on the room's temperature
3. Check the thermostat on the furnace

If you answered #3, sorry, but you can't join the
IPCC.  If you really want to irritate an AGW supporter, ask about the
sun.  To AGW supporters, only a Luddite would check the sun's output when
they could instead be obsessing over the increase in CO2 by 0.009% of the
atmosphere.

When they looked at the problem, the IPCC decided that over
the last 50 years, the sun has been irrelevant to warming.  Note that the
blue band in this chart (described in more detail in the last section), the
IPCC thinks that without man, the world would have cooled over the last 50
years:

Further, when they detailed different climate forcings, the
forcing from changing solar irradiance was a trivial rounding error (though
they had the good grace to mark their understanding of this as "low") meaning
the sun has very little effect vs. what the sun had in 1850 (in the Little Ice
Age!)

But it turns out, interestingly, that solar irradiance may be close to its
highest point in centuries.  Al Gore says that current global temperatures
are the highest they have been in 1000 years.  A new study by
the Institute of Astronomy in Zurich says that the "sun is more active now
than it has been at anytime in the previous 1,000 years."  Related?

Sunspots have been monitored on the Sun since 1610,
shortly after the invention of the telescope. They provide the longest-running direct
measurement of our star's activity.

The variation in sunspot numbers has revealed the
Sun's 11-year cycle of activity as well as other, longer-term changes.

In particular, it has been noted that between about
1645 and 1715, few sunspots were seen on the Sun's surface.

This period is called the Maunder Minimum after the
English astronomer who studied it.

It coincided with a spell of prolonged cold weather
often referred to as the "Little Ice Age". Solar scientists strongly
suspect there is a link between the two events - but the exact mechanism
remains elusive....

But the most striking feature, he says, is that
looking at the past 1,150 years the Sun has never been as active as it has been
during the past 60 years.

Over the past few hundred years, there has been a
steady increase in the numbers of sunspots, a trend that has accelerated in the
past century, just at the time when the Earth has been getting warmer.

The data suggests that changing solar activity is
influencing in some way the global climate causing the world to get warmer.

We can look at solar output over large time frames by
looking at the production of carbon-14 (less is produced in years of high solar
activity, and vice versa).  The analysis below used the ratio of oxygen
isotopes in the stalagmites to estimate the water temperature at the time they
were formed.  The result is an interesting correlation between solar
activity and a global temperature proxy over a long time-scale (Graph from Neff et al., 2001):

Over the last 1000 years, we see that (again using a
reversed scale of C14 as a proxy) solar activity is highly correlated with long
term temperature trends (I have used the pre-Mann chart, because while it may
over-emphasize the Medieval Warm Period, I still think such a period existed).

               
Solar Output
Anomaly                                                                      

              Temperature Anomaly

Look at the following reconstruction data by Judith Lean of
the Naval Research Library and charted from her data at NOAA by Junkscience.com
shows that interestingly, the sun's output does appear to be higher today than
they have been in many, perhaps hundreds of years

Would such increased activity be expected to result in
higher Earth temperatures?  I don't know, and there are some issues one
has to be careful with on this chart.  Most importantly the scaling:
While the shape of the curve looks a lot like the temperature trend over the
last 400 years, note that the entire variation from the low to the high point
is only about 0.25% "“ the scaling makes it look more dramatic.  Of course,
the same could be said for global temperature, where a half degree C
temperature increase on an absolute Kelvin scale would only be about 0.17%, so
an argument can be made that on a percentage basis, this change in irradiance
is about the same order of magnitude as our change in temperature.  A more
sophisticated comparison might say that since black body radiation is related
to absolute temperature to the fourth power, .25% increase in irradiance would
be expected to heat the Earth by .06%.

The chart on the above left compares the recent temperature
anomaly to solar irradiance, while the chart on the right compares it to CO2
concentrations.  Neither is a beautiful fit (and one may have to include
aerosols in either scenario to account for 1970's cooling) but solar irradiance
seems at least as good as that of CO2.  Remember, the IPCC shows
the world cooling due to solar effects during the same time the red solar
irradiance line is peaking. 

Recently Alexander et. al. in have done some very comprehensive
work relating solar irradiance and rainfall.  The study posits that one of
the reasons for less than perfect fit of sunspot and irradiance data with
temperature is that the Sun actually works on a 21 year cycle when the sunspot
cycle is combined with the cyclical wobble of the Suns motion through
space.  The study concluded:

The
Intergovernmental Panel on Climate Change (IPCC) (2001) dismisses the view that
solar activity has a meaningful influence on global climate. The basis for this
view is that variations in the receipt of solar activity are too small to
account for variations in the climatic responses. These variations were
determined from satellite and other observations. What the IPCC scientists
failed to appreciate is that changes in the level of solar radiation received
on earth are amenable to precise calculation. The variations are well in excess
of the IPCC value of +0,3 Wm"“2 quoted earlier.

One of the interesting things about solar output is that, if
it is really higher, we should see effects on other planets, not just on
Earth.  And, in fact, a lot of evidence has been pouring in over the last
5 years from astronomers (not climate guys) that the rest of the solar system
has been warming dramatically.

Take
Mars, for example.  Mar's ice caps have been melting and diminishing
since NASA's Mars Global Surveyor and Odyssey started to measure them around
2002. 

Changes in the red spot on Jupiter
seem to be a sign of warming temperatures.  And Neptunes moon Triton is
warming.  We have to be careful with how we draw conclusions on these
outer planets, since their "year" is so long, seasonal changes can last
decades. 

And
on Neptune:

As seen in Figure 1, Neptune has been getting
brighter since around 1980; furthermore, infrared measurements of the planet
since 1980 show that the planet has been warming steadily from 1980 to 2004. As
they say on Neptune, global warming has become an inconvenient truth. But with
no one to blame, Hammel and Lockwood explored how variations in the output of
the Sun might control variations in the brightness of Neptune.

Figure 1 (a) represents the corrected visible light from Neptune from 1950 to
2006; (b) shows the temperature anomalies of the Earth; (c) shows the total
solar irradiance as a percent variation by year; (d) shows the ultraviolet emission
from the Sun (Source: Hammel and Lockwood (2007)).

What would seem so simple statistically is
complicated by the degrees of freedom in the various time series which is
related to the serial correlation in the data (e.g., next year's value is
highly dependent on this year's value). Nonetheless, they find that the
correlation coefficient between solar irradiance and Neptune's brightness is
near 0.90 (1.00 is perfect). The same relationship is found between the Earth's
temperature anomalies and the solar output. Hammel and Lockwood note "In other
words, the Earth temperature values are as well correlated with solar
irradiance (r = 0.89) as they are with Neptune's blue brightness (|r| >
0.90), assuming a 10-year lag of the Neptune values." The temporal lag is
needed to account for the large mass of Neptune that would require years to
adjust to any changes in solar output.

Hammel and Lockwood conclude that "In summary, if
Neptune's atmosphere is indeed responding to some variation in solar activity
in a manner similar to that of the Earth albeit with a temporal lag" then
"Neptune may provide an independent (and extraterrestrial) locale for studies
of solar effects on planetary atmospheres."

More on the sun's
variance and climate change here.

Cosmic Rays

One of the problems with irradiance as a driver for climate
change is that though the changes seem to be fairly well correlated with the
temperature anomaly, many scientists think the magnitude is too small to
totally account for temperature changes.  It is ironic that AGW supporters
use this as a refutation of the sun's effect, since they have exactly the same
problem with CO2, and must posit huge positive feedback loops to justify their
forecasts. 

A second, newer theory has emerged as to a potential second
warming effect of solar output.  To understand it, we have to start with
clouds.  For those that don't live in a hot climate like I do here in
Phoenix, I will give everyone a bit of background "“ clouds cool things
off.  Ok, as with everything in climate, things are actually far more
complicated "“ high clouds can sometimes cause warming, and nighttime clouds can
actually slow cooling.  Never-the-less, in general, cloudcover cools things
off by blocking out and reflecting the sun's energy.

Clouds are in fact such a strong cooling force that is has
been estimated by several sources (Theodor Landscheidt, 1998) that having
clouds cover 1% more of the Earth's surface would cancel the heating effect of
a doubling of CO2.   In fact, it was one of my criticisms earlier
that AGW theory seems overly intent on finding positive feedback loops, while
not considering negative feedbacks seriously enough "“ one such potential
negative feedback is that on a warmer Earth, more water is evaporated into
clouds, in turn cooling things back off.

But recently, an interesting new theory on cloud formation
has emerged.  In short, it holds that cosmic rays, which are the high
energy particles that arrive at Earth from supernovas, spur cloud formation by
ionizing air molecules that act as seeds for water condensation and cloud
formation.  This sounds wild, but really no wilder than warming by a gas
(CO2) that makes up a near trivial portion of the atmosphere.  Like CO2 warming,
this effect has been observed in various laboratory chambers.  But is it
really a measurable driver of climate?

Henrik
Svensmark and Eigil Fris-Christensen looked at historic data on cloud cover
and cosmic ray incidence, from various measuring points.  Their data was
extended and refined by Shiva in 2005.

Cosmic rays
vs. CO2 detailed

So what changes cosmic ray flux to the Earth?  The
biggest influence is the sun.  When the sun's output is high, cosmic rays are
prevented from hitting the Earth, and vice versa.  So high solar activity
corresponds to low cosmic ray flux and therefore lower cloud formation and
higher temperatures. 

While the link between solar irradiance levels and warming
is pretty straight forward, the cosmic ray cloud formation proposition is still
in its infancy.  Those of us who criticize AGW supporters for running past
the evidence on CO2 should not make the same mistake on cosmic rays, and movies
such as The Global Warming Swindle have gone too far in portraying this
alternate theory as fact.

Man's Land Use

Recently, Roger Pielke has done a substantial amount of
research on a different type of anthropogenic forcing.  Specifically, he
has hypothesized that man's changing patterns of land use can be a substantial
driver of regional climate, including temperature and even more particularly,
precipitation.   For example, clearing relatively dry land and
replacing it with irrigated agriculture substantially changes to the local heat
balance,  not the least by increasing humidity.  Dr. Pielke explains
summarizes the consequences on his web site:

Humans are significantly altering
the global climate, but in a variety of diverse ways beyond the radiative
effect of carbon dioxide. The IPCC assessments have been too conservative in
recognizing the importance of these human climate forcings as they alter
regional and global climate. These assessments have also not communicated the
inability of the models to accurately forecast the spread of possibilities of
future climate. The forecasts, therefore, do not provide any skill in
quantifying the impact of different mitigation strategies on the actual climate
response
that would occur.

The table of contents for the rest of this paper, . 4A Layman's Guide to Anthropogenic Global Warming (AGW) is here.  Free pdf of this Climate Skepticism paper is here and print version is sold at cost here

The open comment thread for this paper can be found here. 

Until I watched the Global Warming Swindle, I had confined my criticisms of anthropogenic global warming theory to two general areas:  1)  The models for future warming are overstated and 2) The costs of warming may not justify the costs of preventing it.

The movie offered an alternate hypothesis about global warming and climate change that, rather than refute the magnitude of anthropogenic global warming, provided a counter hypothesis.  You should watch the movie, but the counter hypothesis is that historic temperature changes have been the result of variations in solar activity.  Rather than causing these changes, increased atmospheric CO2 levels resulted from these temperature increases, as rising ocean temperatures caused CO2 to be driven out of solution from the world's oceans.

I thought one of the more compelling charts from Al Gore's pPwerpoint deck, which made the movie An Invconvienent Truth, was the hundred thousand year close relationship between atmospheric CO2 levels and global temperature, as discovered in ice core analysis.  The Swindle movie, however, claims that Gore is hiding something from that analysis in the scale of his chart -- that the same ice core analyses show that global temperature changes have led CO2 concentration changes by as much as 800 years.  (short 2-minute snippet of this part of the movie here, highly recommended).

Well, this would certainly be something important to sort out.  I have not done much real science since my physics days at Princeton, but my sense is that, except maybe at the quantum level, when B follows A it is hard to argue that B caused A.

So I have poked around a bit to see -- is this really what the ice core data shows, or is Swindle just making up facts or taking facts out of context ala the truther hypotheses about 9/11?  Well, it turns out that everyone, even the die-hard global warming supporters, accept this 800-year lag as correct (Watch the Al Gore clip above -- it is clear he knows. You can tell by the very careful way he describes the relationship).  LuboÃ…¡ Motl summarizes in his blog:

However, the most popular - and the most straightforward - explanation
of the direction of the causal relationship is the fact that in all
cases, the CO2 concentration only changed its trend roughly 800 years
after temperature had done the same thing. There have been many papers
that showed this fact and incidentally, no one seems to disagree with
it....

The whole "group" at RealClimate.ORG
[ed: one of the leading sites promoting the anthropogenic theory] has agreed that there was a lag. But they say that in the first 800
years when the influence of temperature on CO2 is manifest, it was
indeed temperature that drove the gases. But in the remaining 4200
years of the trend, it was surely the other way around: CO2 escalated
the warming, they say.

Frequent readers will know that I have criticized forward looking climate models on many occasions for being too reliant on positive feedback processes.  For example, in the most recent IPCC models, over 2/3 of future warming come not from CO2 but from various positive feedback effects (section 8.6 of the 2007 report). 

The folks at RealClimate.org are similarly positing a positive feedback mechanism in the past -- "something" causes initial warming, which drives CO2 to outgas from the oceans, which causes more warming, etc. 

I am not sure I have ever done so, so let me take a minute to discuss positive feedbacks.  This is something I know a fair amount about, since my specialization at school in mechanical engineering was in control theory and feedback processes.  Negative feedback means that when you disturb an object or system in some way, forces tend to counteract this disturbance.  Positive feedback means that the forces at work tend to reinforce or magnify a disturbance.

You can think of negative feedback as a ball sitting in the bottom of a bowl.  Flick the ball in any direction, and the sides of the bowl, gravity, and friction will tend to bring the ball back to rest in the center of the bowl.  Positive feedback is a ball balanced on the pointy tip of a mountain.  Flick the ball, and it will start rolling faster and faster down the mountain, and end up a long way away from where it started with only a small initial flick.

Almost every process you can think of in nature operates by negative feedback.  Roll a ball, and eventually friction and wind resistance bring it to a stop (except, apparently, on the greens at Augusta).  There is a good reason for this.  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."   I can illustrate this with an example:  Nuclear fission is a positive feedback process.  A high energy neutron causes the fission reaction, which produces multiple high energy neutrons that can cause more fission.  It is a runaway process, it is dangerous and unstable.  We should be happy there are not more positive feedback processes on our planet.

Since negative feedback processes are much more common, and since positive feedback processes almost never yield a stable system, scientists assume that processes they meet are negative feedback until proven otherwise.  Except in climate, it seems, where everyone assumes positive feedback is common.

Back to the climate question.  The anthropogenic guys are saying that when the earth heated, it caused CO2 to outgas from the oceans, which in turn caused more warming, which causes more outgassing, etc.  But where does it stop?  If this is really how things work, why isn't the Earth more like Venus?  If you are going to posit such a runaway process, you have to also posit what stops it.  So far, the only thing I can think of is that the process would stop when the all bands of light that are absorbable by CO2 are fully saturated.

But the feedback is worse than this.  I won't go into it now, but as you can see from this post, or from section 8.6 of the 2007 IPCC report, the current climate models assume that warming from CO2 itself yields further positive feedback effects (e.g. more humidity) that further accelerate warming, acting as a multiplier as great as 3-times on CO2 effects alone.

So here is the RealClimate view of the world:  Any small warming from some outside source (think Mr. Sun) is accelerated by outgassing CO2 which is in turn accelerated by these other effects in their climate models.  In other words, global temperature is a ball sitting perched on the top of a mountain, and the smallest nudge causes it to accelerate away.  This is the point at which, despite having only limited knowledge about the climate, I have to call bullshit!  There is just no way our planet's climate could be as stable as it has been long-term and be built on such positive feedback loops.  No way.  Either these folks are over-estimating the positive feedback or ignoring negative feedbacks or both.  (and yes, I know we have had ice ages and such but against the backdrop of the range of temperatures the Earth theoretically could have in different situations, our climate variation has been small).

Postscript:  The other day I mentioned that it was funny a group studying solar output felt the need to put in a statement validating anthropogenic global warming despite the fact that nothing in their research said any such thing.  Motl points to a similar thing in the ice core studies:

Well, the website tells us that the paper that reported the lag contained the following sentence:

• ...
  is still in full agreement with the idea that CO2 plays, through its
  greenhouse effect, a key role in amplifying the initial orbital forcing
  ...

Again, this statement was included despite the fact that their study pretty clearly refutes some key premises in anthropogenic global warming theory.  It's become a phrase like "no animal was hurt in the filming of this movie" that you have to append to every climate study.  Or, probably a better analogy, it is like Copernicus spending a few chapters assuring everyone he still believes in God and the Bible before he lays out his heliocentric view of the solar system. 

Update: All this is not to say that there are not positive feedback loops in climate.  Ice albedo is probably one -- as temperatures rise, ice melts and less sunlight is reflected back into space by the ice so the world warms more.  My point is that it does not make any sense to say that positive feedback processes dominate.

Correction: Like a moron, I have been using anthropomorphic rather than anthropogenic to refer to man-made climate effects.  Oops.  Thanks to my reader who corrected me.  I have fixed this article but am too lazy to go back and edit the past.

Further Update:  The irony of my correction above juxtaposed against the title of the previous post is not lost on me.

Update to the Postscript: Oh my god, here it is again.  An NOAA-funded study comes to the conclusion that global warming might actually reduce hurricane strength and frequency.  Nowhere in the study did the researchers touch any topic related to anthropogenic warming -- they just studied what might happen to hurricanes if the world warms for any reason.  But here is that disclaimer again:

"This study does not, in any way, undermine the widespread consensus in the scientific community about the reality of global warming," said co-author Brian Soden, Rosenstiel School associate professor of meteorology and physical oceanography whose research is partly funded by NOAA.

Does the NOAA and other funding bodies actually require that this boilerplate be added to every study?

I finally watched the BBC special Global Warming Swindle and have to say that it presents a pretty good counter-hypothesis to the prevailing theory of anthropomorphic CO2 production to explain recent global temperature changes.  It also hits some good points on what might be motivating the hard core of the environmental movement beyond just concern about global warming, and why the costs of CO2 control are so high.

I have historically accepted the basic hypothesis of anthropomorphic global warming but have been skeptical of the exaggerated outcomes (Al Gore's 26 foot sea-level rise, for example, which is 17 times more than even the IPCC predicts over the next century) and have posited that a warmer but richer world may well be better than a cooler but poorer one.  I have also pointed out the uncertainties in the IPCC analysis that never get mentioned in the press, like the huge uncertainty in the feedback loops that drive much of the temperature change in current models.  For example, the IPCC admits they don't even know the sign of the largest feedback loop (clouds), which is a big uncertainty since about 2/3 or more of the warming in the models come not directly from CO2 but from these feedback loops.

Anyway, most of my past skepticism has been within the framework of these IPCC studies.  However, this documentary casts off the whole framework, offering a counter-hypothesis of solar activity to explain temperature variations.  I thought the most interesting part of the documentary was when they showed Al Gore from An Inconvenient Truth with a multi-thousand year plot of temperature and CO2.  The chart certainly looks compelling, but this movie makes the point that while the two lines move together, the CO2 line is lagging the temperature line by five hundred years.  Meaning that CO2 levels may be linked to temperature, but the causality may be opposite of that implied by Gore. 

The documentary goes on to offer solar activity as an alternative explanation, with graphs of moving curves of solar activity and temperature that seem to show at least as much correlation as Gore's CO2 graphs.  They hypothesize that rising temperatures driven by changes in solar
activity heat up oceans over time and cause them to release CO2 into
the atmosphere.  I don't think the evidence is definitive, but it certainly casts doubt as to whether we really know what is going on.  I always thought it a bit odd that people would search for the causes of changing temperatures without first checking out the sun, sortof like walking in a room that is too hot and trying to fix it without first checking the thermostat.  This is particularly true given new evidence that other planets are warming, presumably due to solar activity (unless, of course, it's an Exxon plot).

By the way:  Advocates of the anthropomorphic theory are criticizing this movie in part because it does not use Mann's hockey stick temperature chart.  Sorry, but if they want to claim the scientific high ground, I think they need to stop tying their argument to this weak study.  Statisticians have dumped on it repeatedly (apparently random white noise fed into their model produces a hockey stick) and the evidence for eliminating the Medieval warm period is based on the rings in one or two trees.