If You Don't Like People Saying That Climate Science is Absurd, Stop Publishing Absurd Un-Scientific Charts
Kevin Drum can't believe the folks at the National Review are still calling global warming science a "myth". As is usual for global warming supporters, he wraps himself in the mantle of science while implying that those who don't toe the line on the declared consensus are somehow anti-science.
Readers will know that as a lukewarmer, I have as little patience with outright CO2 warming deniers as I do with those declaring a catastrophe (for my views read this and this). But if you are going to simply be thunderstruck that some people don't trust climate scientists, then don't post a chart that is a great example of why people think that a lot of global warming science is garbage. Here is Drum's chart:
The problem is that his chart is a splice of multiple data series with very different time resolutions. The series up to about 1850 has data points taken at best every 50 years and likely at 100-200 year or more intervals. It is smoothed so that temperature shifts less than 200 years or so in length won't show up and are smoothed out.
In contrast, the data series after 1850 has data sampled every day or even hour. It has a sampling interval 6 orders of magnitude (over a million times) more frequent. It by definition is smoothed on a time scale substantially shorter than the rest of the data.
In addition, these two data sets use entirely different measurement techniques. The modern data comes from thermometers and satellites, measurement approaches that we understand fairly well. The earlier data comes from some sort of proxy analysis (ice cores, tree rings, sediments, etc.) While we know these proxies generally change with temperature, there are still a lot of questions as to their accuracy and, perhaps more importantly for us here, whether they vary linearly or have any sort of attenuation of the peaks. For example, recent warming has not shown up as strongly in tree ring proxies, raising the question of whether they may also be missing rapid temperature changes or peaks in earlier data for which we don't have thermometers to back-check them (this is an oft-discussed problem called proxy divergence).
The problem is not the accuracy of the data for the last 100 years, though we could quibble this it is perhaps exaggerated by a few tenths of a degree. The problem is with the historic data and using it as a valid comparison to recent data. Even a 100 year increase of about a degree would, in the data series before 1850, be at most a single data point. If the sampling is on 200 year intervals, there is a 50-50 chance a 100 year spike would be missed entirely in the historic data. And even if it were in the data as a single data point, it would be smoothed out at this data scale.
Do you really think that there was never a 100-year period in those last 10,000 years where the temperatures varied by more than 0.1F, as implied by this chart? This chart has a data set that is smoothed to signals no finer than about 200 years and compares it to recent data with no such filter. It is like comparing the annualized GDP increase for the last quarter to the average annual GDP increase for the entire 19th century. It is easy to demonstrate how silly this is. If you cut the chart off at say 1950, before much anthropogenic effect will have occurred, it would still look like this, with an anomalous spike at the right (just a bit shorter). If you believe this analysis, you have to believe that there is an unprecedented spike at the end even without anthropogenic effects.
There are several other issues with this chart that makes it laughably bad for someone to use in the context of arguing that he is the true defender of scientific integrity
- The grey range band is if anything an even bigger scientific absurdity than the main data line. Are they really trying to argue that there were no years, or decades, or even whole centuries that never deviated from a 0.7F baseline anomaly by more than 0.3F for the entire 4000 year period from 7500 years ago to 3500 years ago? I will bet just about anything that the error bars on this analysis should be more than 0.3F, much less the range of variability around the mean. Any natural scientist worth his or her salt would laugh this out of the room. It is absurd. But here it is presented as climate science in the exact same article that the author expresses dismay that anyone would distrust climate science.
- A more minor point, but one that disguises the sampling frequency problem a bit, is that the last dark brown shaded area on the right that is labelled "the last 100 years" is actually at least 300 years wide. Based on the scale, a hundred years should be about one dot on the x axis. This means that 100 years is less than the width of the red line, and the last 60 years or the real anthropogenic period is less than half the width of the red line. We are talking about a temperature change whose duration is half the width of the red line, which hopefully gives you some idea why I say the data sampling and smoothing processes would disguise any past periods similar to the most recent one.
Update: Kevin Drum posted a defense of this chart on Twitter. Here it is: "It was published in Science." Well folks, there is climate debate in a nutshell. An 1000-word dissection of what appears to be wrong with a particular analysis retorted by a five-word appeal to authority.
Update #2: I have explained the issue with a parallel flawed analysis from politics where Drum is more likely to see the flaws.
I'm generally familiar with most of what you've set forth here, just as a curious information addict, not as a specialty. I know of the history of CO2 modeling and the initial work from the 1930s. I know about Hansen's early 3 predictions. You didn't mention that these three predictions were not ranges of possibility but rather predictions based off future human action, and that while humanity has generally continued CO2 at a rate Hansen used for his very large (and now very inaccurate) prediction his underestimate was based on an almost elimination do human added CO2. So to say he modeled 2 high and 1 low seems a bit disingenuous of you.
Regarding the 70+, or "ALL" models in the upper troposphere that I mentioned...these in my understanding are not historical artifacts...they are the sum total of IPCC forward looking models since climate scientists started doing them in the 70s up until now. And on the graphs I've seen, updated as recently as last month, all 70+ underestimate the warming that has, in fact, occurred. This troubles me greatly. It leads me to believe either the science, the modeling capabilities, the intentions or some combination of all three are biased towards warming.
I don't doubt warming has been happening, nor do I think that's unusual as we are on a historical exit period from an ice age. I don't doubt humankind has an impact on our environment...a glance out my window informs me it does. But I do question the science and intentions of those who seem to be scrambling to justify their short scientific history and seem to have political policy intentions that direct their science more than their science guides their policy.
Hansen: No, actual anthropogenic forcing (GHG + aerosol) has been between the B and C scenarios -- Skeie et al. (2011). Hansen is crude, but you can think of the forcing terms as incorporating both economic emissions and atmospheric multipliers. Somewhere between B and C is where we are today and however much serendipity involved the prediction wasn't bad.
But, I don't really care. Hansen is: An Old highly simplified model. Not tested for starting condition sensitivity. Assumptions not equal to reality. Being tested on time scale for which it wasn't intended to be used. Model results matching current temperature changes is at least partly serendipity. Hansen isn't "the truth." It's an old model being misapplied to a data set it was never meant to match with precision.
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What you appear to be looking at compiled model results from tens or hundreds of different runs for each model (a link would help me sort it out for you). As such the trend would average out inherent noise in these chaotic simulations and give you the component related to external forcing. If there is any forcing it's going to be an increasing curve and the more averaging done the smoother it gets -regardless of the scale of the noise and the forcing.
What you want to look at are the individual model simulations and the spread of possible paths. The models only crudely represent the earth's complexity on this time scale but they do represent enough of it to be filled with lots of starting point dependent noise -- including the fairly common warming "hiatus" and short cooling trend on top of the overall curve.
The earth has only gone through one simulation since 1988. If we could rerun it 100 times and average them it might start to look like one of the computer model compilations.
A quick google got me this of 44 models: http://www.drroyspencer.com/wp-content/uploads/CMIP5-global-LT-vs-UAH-and-RSS.png
I'm sure it's from an advocate website from the other side of real climate.org, but unless you can show me the data vs the models is wrong it stands for me. I've seen a more recent update of this that included the 70 or so most commonly referenced temperature models from the 1970s to more "modern" models up until temperature data up until a few months ago. The trend of modeled vs actual had only widened since whenever the above linked comparison was made. Again...unless these examples are outright lies the model vs reality troubles me, and if it didn't trouble you that would trouble me as well.
Reality after 35 years of real data should at least fall somewhere within the average of the models, or the models should be acknowledged as faulty. If merely faulty, thank God they were faulty in a "safer" direction. If purposefully biased, it is a scientific scandal of historical proportion.
I should add that in my understanding, the fact that modeling started in the 1970s also bothers me, as in my memory the 1970s was quite cold and many were discussing the possibility of entering another ice age. If the models started in the 1950s or 1880s or whenever, what would they show vs reality?
Quick googling can get you a lot of things.
This in particular is basically the definition of cherry picking.
UAH and RSS are not surface temperature estimates. They are satellite estimates of lower troposphere temperature. They are actually two different algorithms analyzing the same data from the same instrument (to filter out contamination from signal higher up in the colder stratosphere among other things). They are works in progress and if you look over time you'll see that they have revised UAH warming rates from initial negative rates (?) to 0.1 deg/decade to the current 0.14 deg/decade. Compared to 0.17 for surface-instrument-based temperature compilations.
I'm not sure what iteration is plotted here but you usually see UAH plotted in skeptic literature because it's the lowest rate found in any available compilation for global temperature change. Sort of the definition of cherry picking. In addition, it doesn't reflect the surface and may reflect an elevation that changes through time. It's complicated by known measurement contamination. Expected changes in atmospheric temperature structure should send these numbers on a different trajectory from surface temperatures. Models aren't likely to capture this complexity.
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A fair representation of model means would predict GHG-related warming rates between 0.15 to 0.3 (more or less what's represented on the graph). However, simulation variablity isn't represented well here. A 95% confidence error bar on model simulations would be include the possibility that 2010 was no warmer than the 1980-1999 average. CO2 forcing isn't the only thing going on and the system and models reflect more short-term complexity. These models don't predict short-term climate with precision and they weren't intended to.
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I think one makes a mistake throwing most scientists in the advocate box (differentiates much of realclimate.org from your link in my mind). Most have their head in the books and are shocked a bit when they get thrust in the news. Defending their work in this type of forum is a little different from a layperson advocate (or scientist advocate) misrepresenting the work as an alarmist or denialist. The science can be separated from the advocacy and policy aspects. And the science can be argued about on a fairly impartial fact-based level.
Yes...in my earlier responses I said I understand this chart graphs temperature in the troposphere, not surface temps. I also mentioned that it is my understanding that this is important because the lower troposphere is precisely the place climate scientists said greenhouse warming would be most evident...in other words, this is where the warming should show up first. Is this not true?
The actual data seem to disprove the models to me. I also haven't heard an acceptable explanation for the last 16-17 year "pause" while CO2 emissions have increased. The ocean heat sink explanation doesn't work for me. I did have coursework in statics, dynamics and heat transfer back in my engineering days, and what I've read is not convincing...it all seems more of a desperate stab at a scientific sounding excuse for the recent lack of warming.
Satellite data is not a direct measurement of troposphere temperatures. From wiki:
"The process of constructing a temperature record from a radiance record is difficult. The satellite temperature record comes from a succession of different satellites and problems with inter-calibration between the satellites are important, especially NOAA-9, which accounts for most of the difference between various analyses.[17] NOAA-11 played a significant role in a 2005 study by Mears et al. identifying an error in the diurnal correction that leads to the 40% jump in Spencer and Christy's trend from version 5.1 to 5.2.[18] There are ongoing efforts to resolve differences in satellite temperature datasets."
It's a work in progress. I really don't know whether your skeptic is using UAH 3 or 5.1 or 5.2. But it matters and from the look of it I suspect it's before the 40% shift in the trend.
If that sounds like scientific gobbledygook just consider that it comes from the authors of the record. As I'm only peripherally in the field my strategy is to wait five years and read some papers.
Using the most controversial temperature record by itself because it shows the slowest current warming rate is cherry picking.
I suspect myself that we'll find some confounding water vapor effects in the satellite record. In warmer tropical sites we might be looking at a temperature higher in the troposphere than we think. And of course we have contamination with low temperature signals in the stratosphere. Not sure how it will sort out, but it's not easy.
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As of 2010 UAH showed a model confounding relative decrease in tropospheric temperatures and RSS showed a model supporting increase in tropospheric temperatures. Both are from the same instruments. Again, I'd wait five years.
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If you wanted to look at robust model predictions I'd go with temperature increases in the high arctic. In particular sea ice thickness and sea ice extent. A long term record of winter low temperatures in the Arctic is pretty edifying too. It's like we put a wool hat on the top of planet. It's exactly where the models respect a maximum response.
I can definitive state that there was no global warming at all before 4004 B.C.E. which obviously skews the chart. If you don't believe me, look it up.
It was published in the Bible.
Don't count those other policies as out, just because they've been on the ropes a few decades
Be stupid and delusional somewheres else.
Quick question; if in the last two slices the temp drops by 1.3 and then rises by 1.3, why isn't it back where it started at the beginning of the dropping slice?
WOW.....you are REALLY missing the boat. I think you are even missing the dock.......
There is NO ICE CORE DATA.....or any other data......that show anything DIFFERENT from that chart. And you are bitching because the data since 1850 is done on a daily basis? Great.....then smooth it yourself. The chart would look EXACTLY THE SAME. You still have to get from the temperature in 1850 up to the temperature NOW.....
Nice try.....:)
There data and data sets are QUITE PUBLIC.....and QUITE NUMEROUS. And they show the same thing (within small differences). There were not scientists cherry picking data. There was no faking of data. You've been watching Glenn Beck and Sean Hannity too much..... You've been brainwashed. Look at the facts.....they CLEAR.....they are NUMEROUS.....and they are CONSISTENT.