11 December 2012

IPCC Climate Forecast from 1990- Amazingly Accurate.

Posted by Dan Satterfield


Read the blog post below BEFORE watching the Carl Sagan lecture from last weeks AGU Annual meeting. I missed this year’s but I will be there in 2013. It’s the biggest Earth Science meeting on the planet.

There is probably no scientific body that has been ridiculed by those who know nothing about science more than the Intergovernmental Panel on Climate Change. So much so that if someone criticizes them you can be nearly certain that the person doing it has a political axe to grind and it not interested in the real science.

The IPCC does indeed deserve some criticism it seems, there is growing evidence that they are making the same mistake that most scientific predictions make. They are being too conservative. At least as far as seal level rise predictions; the temperature predictions have been amazingly accurate.

From Comparing Climate Projections to Observations by Rahmstorf et. al in Env. Res.Letters (AGU)

Two new papers recently published caught my eye, and basically leave those who still harbor doubts about the reliability of the science in a tiny group of those who are immune to facts. This is not unusual in science, in fact it’s almost always the case that not everyone in a particular field will accept a new paradigm. The holdouts tend to diminish down to just a handful eventually. Those remaining few that will not accept the reality usually take their objections to the grave, leaving the world to march forward. It was true with relativity, the false belief in the aether, and even biological evolution and plate dynamics. All are acccepted scientific facts now.

The first paper (open access) is a look back at how the IPCC early 90’s projections have panned out. All in all, not bad but they underestimated the sea level rise (knowing they would do so since they could not estimate how much melting ice would contribute, and only factored in the expansion of warmer ocean water). The next IPCC report will have a much better estimate on sea level rise, and the overwhelming opinion the climate science community seems to be that it will be considerably higher.

The second paper is by Dr. Ben Santer, along with 20 other scientists from varying institutions  It puts to rest the frequently heard canard that “yea the Earth is warming but it’s all natural”.  Dr. Santer is an expert in doing what are called Detection and Attribution studies. A better name is scientific fingerprinting. Using the most sophisticated atmospheric models ever built, this paper shows that the only explanation for the changes we have seen over the past decades is rising levels of greenhouse gases. This paper is also open access and gets into signal to noise ratio statistics, but I still recommend taking a look at it, no matter what your math background!

In short, Santer and colleagues read the different components of our atmosphere their rights, and then  booked and fingerprinted them. Whose fingerprints were a match on the stolen car of climate change ??

Fossil fuels and hair spray.

What they did was take the actual satellite record of troposphere and stratosphere temperatures and then tried to reproduce it using the latest global climate models. They found that in nearly every case they could not do it without adding in the rising levels of greenhouse gases along with a deteriorating level of stratospheric ozone. Both of which is human caused.

Here is a snippet from the conclusion:

Our fingerprint results are interpretable in terms of basic
physical mechanisms. The global-scale lower stratospheric cooling
is primarily a direct radiative response to human-caused depletion
of stratospheric ozone (29, 39, 58). Tropospheric warming is
mainly driven by human-caused increases in well-mixed greenhouse gases.

The multidecadal cooling of the stratosphere and warming of the troposphere,
which is evident in all satellite datasets and simulations of forced climate change examined here,

cannot be explained by solar or volcanic forcing, or by any known
mode of internal variability.

Now, watch the Carl Sagan Lecture at the AGU San Francisco. 

Correction- I sad the AGU was the biggest science meeting on the planet. It is the biggest Earth Science meeting. Thanks MJ for catching that!