People who claim that “the science is settled” on global warming have to be pretty unsettled by the science news in the last week.
“Setttled science”, of course, means that we are inevitably headed toward a disastrous warming of surface temperatures as forecast by some computer models, and we therefore need an international carbon tax or cap-and-trade system, pronto.
Settled science would know all of the important “forcings” and “feedbacks” in the climate system, such as the sensitivity of surface temperature to changes in carbon dioxide (a forcing) and the behavior of clouds, which could either enhance or counter warming (a feedback).
Now it appears that cloud tops are lowering, a totally unforeseen cooling feedback on carbon dioxide-induced warming. Writing in Geophysical Research Letters, University of Auckland’s Roger Davies and Matthew Molloy conclude this could be a “significant measure of a negative cloud feedback to global warming”.
The average global cloud height is linked to the average global temperature—generally, the higher the average cloud height, the higher the average surface temperature, and vice versa. The tie-in is related to the height in the atmosphere from which clouds radiate infrared radiation to space. The higher up they are, the cooler they are, and they dissipate less radiation, which means the surface stays warmer.
Problem is that there’s only ten years of data, and there was a pretty decent La Nina (that’s the cold side of El Nino) in the Pacific Ocean in 2008, which was clearly correlated with a decline in cloud top height. Davies and Molloy are therefore properly cautious with their conclusions, but nonetheless note that a comparison of the beginning and endpoints for their study, which minimizes the La Nina contribution, still showed a decline in cloud height.
Who’d a thunk this one? Based upon data from the paper, the cooling climate impact from the decrease in the average global cloud height more than offset the positive forcing from an increase in greenhouse gases from human activities in the last decade.
This is—yet another—explanation in the refereed literature to apologize for recent climate misbehavior. Others include changes in the sun, cruddy air from China, and a change in stratospheric water vapor.
The last one is especially interesting because that, too, is a previously unknown forcing on climate, i.e. another bullet shot at “settled science”.
Then there’s the new icing on the global warming cake. Data from 2003 through 2010 from the Gravity Recovery and Climate Experiment (GRACE) satellite show virtually zero net melting from the massive Himalayan ice cap, the world’s “third pole”. The UN, using an unrefereed publication from the World Wildlife Federation, erroneously forecast in its last climate compendium that it would be gone by 2035. In reality, it will last hundreds of years, and even longer if the current trends reflect how the ice cap reacts to warming.
How could prominent glaciologists like Ohio State’s Lonnie Thompson, who isn’t shy about predicting glacial armageddon (and, who along with his wife, advises Al Gore on matters climatic), have missed this one? Simple—who wants to climb to the top of a Himalayan glacier? That can be close to the oxygen-starved “dead zone” where humans cannot linger. So most measurements have been made from the bottom. It shouldn’t surprise anyone that the top of these behemoths will expand in a warmer world, as the ocean evaporates more moisture which will surely precipitate as snow at higher elevations.
In addition, the GRACE satellite found that total ice loss outside of Greenland and Antarctica was previously estimated 30% too high, another reinforcement of the “lukewarm” synthesis of climate change. After adding in the GRACE measurements for Greenland and Antarctica and median estimates for the “thermal expansion” of water, the current rate of sea-level rise is 8 inches per century. While that surely will rise before 2100, it’s only one inch more than what was observed last century.
What with the finding of yet another cooling feedback, no net melting (within the range of measurement error) in the Himalayan ice cap, and confirmation of a low rate of sea level rise, it’s been a bad week for climate hotheads.
I am a senior fellow in climate studies at the Cato Institute and in research and economic development at George Mason University. I am a contributing author and reviewer of the United Nations Intergovernmental Panel on Climate Change, which was awarded the Nobel Peace Prize in 2007. My writing has been published in major scientific journals, including Climate Research, Climatic Change, Geophysical Research Letters, Journal of Climate, Nature and Science, as well as publications like the Washington Post, Washington Times, Los Angeles Times, USA Today, Houston Chronicle and Journal of Commerce. I have a Ph.D. in ecological climatology from the University of Wisconsin at Madison.