There are a couple of deniers who hang out at Anthony Watts' anti-science blog, WUWT, from time to time. This pair go by the names of Paul C. “Chip” Knappenberger and Patrick J. Michaels. I don't know if they are denialists themselves or not, but they are known for spreading disinformation wherever they can. They are from the Cato Institute, which is a libertarian think tank/lobbying organisation, initially set up by "coal" Koch, that promotes denial of climate science.
This time they have recycled an article from the Economist and are putting a lot of weight on climate sensitivity studies (Bayesian approaches) that tend to the lower end of the suite of projections. Pat 'n Chip are writing as if all studies are showing lower climate sensitivity, which is not so.
First up, I'll point out as have others, that the Economist article was based on something it says is in the working group on mitigation, not on the physical sciences. So it means zilch.
Secondly, climate sensitivity is important to know, but it doesn't have to be known precisely. What is more important to my mind is behaviour. If we double or treble the amount of atmospheric CO2 or worse, we'll definitely turn up the heat to more than we can handle.
I did a quick search of Google Scholar for climate sensitivity studies in the past couple of years. There are swags of them. The only ones that Pat 'n Chip want their readers to know about are the ones that come in at the lower end of the spectrum. But there are many recent studies that come up with the same sort of numbers that the IPCC came up with in the past. It's just that the media hasn't picked up on them. Probably because they are the norm rather than the exception.
Here's a sample from the first few studies that come up in a Google Scholar search:
- Equilibrium = 3.2˚C; transient 1.72˚C
Bitz et al (2012) Climate Sensitivity of the Community Climate System Model, Version 4, J Climate DOI: 10.1175/JCLI-D-11-00290.1
- Equilibrium = 2.2 - 4.8˚K
Rohling et al (2012) Making sense of palaeoclimate sensitivity, Nature DOI: 10.1038/nature11574 (Thanks to BBD for the link to the full paper).
- Equilibrium = 2.1 - 4.7˚K
Andrews et al (2012) Forcing, feedbacks and climate sensitivity in CMIP5 coupled atmosphere-ocean climate models, GRL
- Equilibrium = 1.9˚C (1.2 to 2.9˚C); transient = Using observational data up to and including year 2010 gives a 90% C.I. of 1.0 to 2.1˚C, while the 90% C.I. is significantly broader ranging from 1.1 to 3.4 ˚C if only data up to and including year 2000 is used.
Skeie et al A lower and more constrained estimate of climate sensitivity using updated observations and detailed radiative forcing time series, Geophysical Research Abstracts
Pat 'n Chip would have the scientists exclude all the higher estimates and only publish the lower estimates. Many if not most of the lower estimates seem to come from Bayesian analysis, while the higher ones more commonly come from analysis of past climates (paleoclimatology) or climate models - which are based on physics.
The reason seems to be that they want permission to continue to pollute the atmosphere for a while longer yet. Obviously they don't give tuppence for what happens to humanity, society or any other life on earth in the future. Otherwise they'd be arguing that regardless of whether equilibrium sensitivity was 2˚C (which Pat 'n Chip favour) or 3˚C or 4˚C or higher, if we don't stop burning fossil fuels soon climate change will get much worse.
Thing is, equilibrium sensitivity won't mean zilch if we don't stop at doubling CO2. No-one will be any the wiser about what it would have been. Humans will have to wait until equilibrium does occur for however many multiples of CO2 we pour into the air, which will take thousands of years as illustrated here. (Click to enlarge.)
From the WUWT comments
I was curious to see how the deniers at WUWT would react. After all, Pat 'n Chip are arguing that climate sensitivity is 2˚C. Many deniers at WUWT think CO2 doesn't have any effect on surface temperature. Some even think that we are about to enter an ice age - any day now - and have thought that for quite some time. (They are very patient.)
Pseudo-science gobbledegook from KonradThe response was a mixed lot with people mostly talking past each other. Here is some classic pseudo-science from Konrad, who says pre-industrial CO2 is fictitious, that "LWIR" (does he think there is such a thing as SWIR I wonder?) doesn't affect the cooling rate of water that is free to evaporatively cool - presumably evaporating because of cooling? And radiative gases cool the earth, not heat it!
July 26, 2013 at 5:32 pm “Climate sensitivity” to a doubling from fictitious “pre-industrial” levels would be around -0.00000001 C. To arrive at this figure you of course have to ignore all the evidence that temperature drives atmospheric CO2 concentration at all time scales. Next reduce those ludicrous figures for DWLWIR slowing the cooling of the earths surface by 71percent. LWIR doesn’t effect the cooling rate of water that is free to evaporativly cool.
Now as the troposperic lapse rate created by convective circulation is near the adiabatic limit, there is little need for ajustment here. However speed of convective circulation and mechanical energy transport from the surface should be increased for higher radiative gas concentrations.
The ERL argument can be safely ignored as it is junk science. In a moving atmosphere, warm air masses are transporting energy high above the level of maximum IR opacity, where they always radiate more than the air at the altitude they are rising through. You should find that radiative gases act to cool the atmosphere at all concentrations above 0.0ppm. The IPCC however should continue to do static atmosphere calculations and assume surface IR absorption based on emissivity. Otherwise they won’t get paid.
Asian aerosols caused global warming and incomprehensible quackery from AlecMThis one is a new one for me. AGW was caused by aerosols! (Most aerosols reflect sunlight and have a cooling influence.) This from AlecM:
July 26, 2013 at 11:39 pm My view is that the atmospheric control system that damps out natural fluctuations is near 0 K CO2 climate sensitivity. There has been AGW, from Asian aerosols reducing the albedo of low level clouds. This led to the 1980s and 1990s heating but has now saturated. It lead to the ocean temperature rise What we are seeing now in the reduction of TPW and the turn down of OHC and air temperature is the effect of operation of other parts of the control system. CO2 is automatically eliminated from the temperature effects.
The Other-Andy hasn't looked at a temperature chart since 1979From where on earth does the Other_Andy get his information?
July 27, 2013 at 3:05 am So, according to the warmists CO2 (And positive feedbacks) controls the Earth’s temperature. As CO2 goes up so does the temperature.The Other_Andy's close enough with the CO2 increase, but he says temperature stayed the same between 1979 and 1996? Not so:
Between 1979 and 1996, CO2 increases by 25 ppm (More than 7% increase), there are several El Ninos and the temperature stays the same. What is their explanation?
|Data Sources: NASA and UK Met Office Hadley Centre|