Squaring the Culture

Very recent improvements in analysis techniques make it possible to measure how much current global temperature readings are affected by CO² — and it’s much less than previously assumed.

Strata-sphere posted testimony about a week ago that was delivered in front of the Senate Environment and Public Works Committee on July 22 by Roy Spencer, one of the world’s leading climatologists and US Science Team Leader on NASA’s Aqua satellite instrumentation. Proponents of Anthropogenic Global Climate Change (AGW) hate Dr. Spencer, since he doesn’t agree that humans are at the root of it.

The testimony starts by reasserting Spencer’s 2008 research establishing that when the IPCC leaves ordinary, chaotic cloud formation out of climate models, which all their models do so far, it biases the models in the direction of high sensitivity to CO² changes. When natural cloud variations are included in the models, they all predict low sensitivity to CO² — which would mean that humans are not changing the climate much.

Spencer then adds very recent observed evidence showing a low sensitivity to CO² from his team’s satellite temperature readings. New mathematical analysis techniques developed by his team allow them to separate radiative forcing (Greenhouse Effect warming) from feedback effects in satellite temperature readings, and the results all say that the feedback effects are negative — they stabilize climate rather than forcing big changes. (Recall my lengthy discussion of feedback effects if you’re wondering why this matters.)

I’ll let Dr. Spencer speak for himself for a moment, from the transcript of the testimony:

… in the last several weeks, we have stumbled upon clear and convincing observational evidence of particularly strong negative feedback (low climate sensitivity) from our latest and best satellite instruments. That evidence includes our development of two new methods for extracting the feedback signal from either observational or climate model data, a goal which has been called the “holy grail” of climate research.

The first method separates the true signature of feedback, wherein radiative flux variations are highly correlated to the temperature changes which cause them, from internally-generated radiative forcings, which are uncorrelated to the temperature variations which result from them. It is the latter signal which has been ignored in all previous studies, the neglect of which biases feedback diagnoses in the direction of positive feedback (high climate sensitivity). (Spencer’s emphasis)

Based upon global oceanic climate variations measured by a variety of NASA and NOAA satellites during the period 2000 through 2005 we have found a signature of climate sensitivity so low that it would reduce future global warming projections to below 1 deg. C by the year 2100 … that estimate from satellite data is much less sensitive (a larger diagnosed feedback) than even the least sensitive of the 20 climate models which the IPCC summarizes in its report.

By “natural cloud variability,” Dr. Spencer is talking about all the natural agents other than greenhouse gases that go into forming clouds. In his testimony, he focused on two specific, known, natural patterns that affect cloud formation: the Pacific Decadal Oscillation (PDO) and the El Niño Southern Oscillation (ENSO). The PDO is a decades-long shift from warm surface temperatures to cool ones, then back, in the northern Pacific Ocean that causes significant changes in weather. The ENSO is a much shorter shift in surface temperature (every 2-7 years) occuring east of Indonesia and moving east across the ocean that causes destructive weather changes lasting usually about a year. Both cause changes in cloud patterns, and are not caused by long-term global temperature.

Dr. Spencer’s point about clouds is pretty simple. The models used by the IPCC and AGW proponents assume that CO² in the atmosphere is the only relevant thing that causes clouds to increase or decrease. This assumption changes the outcome of the models in only one direction; it makes the climate seem to respond more wildly to changes in atmospheric CO². If changes in cloud cover are caused by things other than CO², then the model’s assessment of the climate’s sensitivity to CO² is too high. Spencer explains his point at greater length on his own blog site, if you’d like more detail.

Spencer claims that clouds are the major determinant of global temperature. He presents a very simple model that uses natural cloud variations from the ENSO and PDO to predict global temperatures. His simple model produces a global temperature pattern for the 20th century that fits the actual temperatures very neatly.

On this issue, it can be shown with a simple climate model that small cloud fluctuations assumed to occur with two modes of natural climate variability — the El Nino/La Nina phenomenon (Southern Oscillation), and the Pacific Decadal Oscillation — can explain 70% of the warming trend since 1900, as well as the nature of that trend: warming until the 1940s, no warming until the 1970s, and resumed warming since then.

The Strata-sphere article incorrectly claims this constitutes scientific evidence that 70% of the warming is not man-made. It doesn’t prove that; it simply presents a model that matches historical patterns. However, the success of this model in producing historical patterns without having to deliberately “tweak” the model to match the patterns, the way the IPCC modelers have, suggests that the theory underlying the model is sound.

The norm for hard science is that it takes about 30 years for advances among the scientists to make it to the general population. The reason for this is simple; scientists as a group don’t communicate very well to the general public. There’s no mechanism for the progress in hard theory or mathematical representation to get explained clearly to non-scientists.

Unless, of course, somebody’s using science to grab political power. Then, it becomes crucial to understand the flow of scientific thought day-to-day. This is why we’re all staying right on top of the forward progress of climate research.

In my humble estimation, there remain no observed data pointing to a primarily human cause of global climate change. The most likely contributors to global climate patterns are the things we would naturally assume control such things: the sun, cosmic rays, normal, chaotic patterns on the earth (like clouds and ocean currents). Humans do produce some effects, but it’s unlikely that these effects are strong or lasting; we’re just not that powerful. Releasing human liberty into the hands of governments on the off chance that our industry is affecting the climate is a very bad bet, and should be resisted wholeheartedly. There simply isn’t enough evidence to support the claim, and the price of changing — the loss of our God-given liberty — is far too high.