The Island of Doubt

The climate change denial gang is so predictable. Even when the science as written, and as covered by reputable science journalists, makes it clear that the new evidence bolsters the general consensus, there are those who will give the findings the opposite interpretation. Today's topic is sunspots.

The title of the paper in question actually addresses the issue head on: "Solar-Cycle Warming at the Earth's Surface and an Observational Determination of Climate Sensitivity." It's all about using that 11-year sunspot cycle -- the one that produces spectacular aurora and knocks out satellites -- to gauge how sensitive our climate is to changes in the things like greenhouse gas levels. The authors of the as-yet-unpublished paper, Ka-Kit Tung and Charles D. Camp of the University of Washington in sunny Seattle, conclude their paper with:

Since the equilibrium response should be larger than the periodic response measured, the periodic solar-cycle response measurements yields a lower bound on the equilibrium climate sensitivity that is equivalent to a global warming of 2.3 °K at doubled CO2. A 95% confidence interval is estimated to be 2.3-4.1 °K. This range is established independent of models.

For anyone who bothers to try to understand what this means before reporting on it, the important part is the last temperature range. 2.3 to 4.1 degrees (Kelvin = Celcius) is very similar to what the latest estimates of how much the Earth will warm should CO2 levels reach double their pre-industrial maximum -- 3°C.

In other words, this paper supplies independent confirmation of what computer climate models are predicting, which is something climatologists have been yearning for. And this is exactly the interpretation that the venerable Fred Pearce of New Scientist put on his story (subscription req):

Tung says his findings provide important real-world evidence that climate model predictions of global warming are correct. For instance, they show that the temperature changes are two to three times as strong in polar regions. On the face of it this is surprising, because the variation in solar radiation is greatest in the tropics. But Tung says "it reinforces the idea of melting ice as an amplification mechanism in the climate-change models."

What will excite climate scientists most is that Tung and Camp are the first to measure directly how a given change in the amount of heat energy in the atmosphere translates into a change in temperature. Researchers call this the "climate sensitivity" of the atmosphere, and it is a vital factor in climate research because it determines how fast the planet will warm as a result of climate change.

All previous estimates of climate sensitivity have been based on models. Now Tung and Camp have used real figures to show that an extra 0.9 watts per square metre of heating at the Earth's surface, at the height of the 11-year cycle, produces an immediate warming of the atmosphere of 0.16 °C.

So, while the sunspot cycle is responsible for some global warming, its contribution is less than a fifth of a degree, and that effect will reverse itself as we head up toward another solar maximum over the next five years.

This is also in line with the new forecast that we should see serious temperate rises starting in about 2009 or so. But again, the most important thing to take away from the findings, should they survive the peer-review process, is that they in no way undermines the notion that humans are responsible for most of the observed warming. And yet...

And yet the usual suspects did just that. Pearce knew that would happen, and in a perhaps vain attempt to head off that misleading spin, he actually wrote in the lead to his story that:

Climate-change sceptics may seize on the findings as evidence that the sun's variability can explain global warming - but mathematician Ka-Kit Tung says quite the contrary is true.

But there's simply no arguing with some people. Fox News' Brit Hume heralded

"new research by University of Washington mathematicians [that] shows a correlation between high solar activity and periods of global warming" as evidence to support his claim that "[global warming] skeptics are increasingly certain that the scare is vastly overblown." (Media Matters)

Elsewhere in the blogosphere we have

This allows a very short-term real-world feedback to see if his analysis and conclusions are correct. I only hope that in five years, if his prediction is not correct, that he stands up and says that there may have been an error. (Is it Getting Warmer?)

or an even less honest example of taking words out of context:

95% certain that global surface warming is related to the 11 year solar cycle. (Ranting Stan)

Sigh.