John Christy, Climate Scientist, to President’s Council on Environmental Quality (May 13, 2015, testimony)

“On average the models warm the global atmosphere at a rate three times that of the real world.”

“The climate is something we can’t predict. The policy is based upon theory that needs a whole lot of correction to it.”

John Christy, Professor of Atmospheric Science and Director of the Earth System Science Center at the University of Alabama in Huntsville (UAH), has received numerous awards for his development of satellite-based temperature monitoring (with Roy Spencer).

Dr. Christy recently testified before the Committee on Natural Resources on the subject, “CEQ Draft Guidance for GHG Emissions and the Effects of Climate Change Committee on Natural Resources.” Pertinent excerpts follow:

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The basic question under consideration here is to understand whether there is a causal relationship between the carbon emissions generated by a single proposed federal project and possible climate change related to those emissions. It is obvious that the emissions generated by a single project would be vanishingly small in comparison to the current emissions of the global economy or even of the United States as a whole. Because of the minuscule nature of the relative size of its emissions, the impact of a single project on the global climate system would be imperceptible.

Mitigation: Negligible Climate Impact

To demonstrate any impact at all on the climate system, we must scale up the size of the emission changes to a much larger value than that of a single project. By doing so, our tools would then be able to provide some results. Let us assume, for example, that the total emissions from the United States are reduced to zero, today, 13 May 2015. In other words as of today and going forward, there would be no industry, no cars, no utilities, no people – i.e. the United States would cease to exist as of this day. With this we shall attempt to answer the question posed by the NEPA statement which is, essentially, what is the “climate change through GHG emissions.”

Using the U.N. IPCC impact tool known as Model for the Assessment of Greenhouse-gas Induced Climate Change or MAGICC, graduate student Rob Junod and I reduced the projected growth in total global emissions by U.S. emission contribution starting on this date and continuing on. We also used the value of the equilibrium climate sensitivity as determined from empirical techniques of 1.8 °C. After 50 years, the impact as determined by these model calculations would be only 0.05 to 0.08 °C – an amount less than that which the global temperature fluctuates from month to month. [These calculations used emission scenarios A1B-AIM and AIF-MI with U.S. emissions comprising 14 percent to 17 percent of the 2015 global emissions. There is evidence that the climate sensitivity is less than 1.8 °C, which would further lower these projections.]

Because changes in the emissions of our entire country would have such a tiny calculated impact on global climate, it is obvious that single projects, or even entire sectors of the economy would produce imperceptible impacts. In other words, there would be no evidence in the future to demonstrate that a particular climate impact was induced by the proposed regulations. Thus, the regulations will have no meaningful or useful consequence on the physical climate system – even if one believes climate models are useful tools for prediction….

Climate Model Overwarming

Do we understand how greenhouse gases affect the climate, i.e. the link between emissions and climate effects? A very basic metric for climate studies is the temperature of the bulk atmospheric layer known as the troposphere, roughly from the surface to 50,000 ft altitude. This is the layer that, according to models, should warm significantly as CO2 increases. And, this CO2-caused warming should be easily detectible by now, according to models. This provides a good test of how well we understand the climate system because since 1979 we have had two independent means of monitoring this layer – satellites from above and balloons with thermometers released from the surface.

I was able to access 102 CMIP-5 rcp4.5 (representative concentration pathways) climate model simulations of the atmospheric temperatures for the tropospheric layer and generate bulk temperatures from the models for an apples-to-apples comparison with the observations from satellites and balloons. These models were developed in institutions throughout the world and used in the IPCC AR5 Scientific Assessment (2013).

Figure 1: Global average mid-tropospheric temperature variations (5-year averages) for 32 models representing 102 individual simulations (lines). Circles (balloons) and squares (satellites) depict the observations.

Figure 1 provides clear evidence that the models have a strong tendency to over-warm the atmosphere relative to actual observations. On average the models warm the global atmosphere at a rate three times that of the real world. Using the scientific method we would conclude that the models do not accurately represent at least some of the important processes that impact the climate because they were unable to “predict” what has occurred. In other words, these models failed at the simple test of telling us “what” has already happened, and thus would not be in a position to give us a confident answer to “what” may happen in the future and “why.” As such, they would be of highly questionable value in determining policy that should depend on a very confident understanding of how the climate system works.

There is a related climate metric that also utilizes atmospheric temperature which in models has an even larger response than that of the global average shown above. This metric, then, provides a stronger test for understanding how well models perform regarding greenhouse gases specifically. In the models, the tropical atmosphere warms dramatically in response to the added greenhouse gases – more so than that of the global average atmospheric temperature.

In the tropical comparison here, the disparity between models and observations is even greater, with models on average warming this atmospheric region by a factor of four times greater than in reality. Such a result re-enforces the implication above that the models have much improvement to undergo before we may have confidence they will provide information about what the climate may do in the future or even why the climate varies as it does. For the issue at hand, estimates of how the global temperature might be affected by emission reductions from the halting of projects would be over done and not reliable.

As such greenhouse gas emissions cannot be used as a proxy for alleged climate change because our capability to demonstrate how greenhouse gases influence the already-observed climate is so poor.