34 Responses to Journal of Climate: New cloud feedback results “provide support for the high end of current estimates of global climate sensitivity”
Co-author Kevin Hamilton concludes, “If our model results prove to be representative of the real global climate, then climate is actually more sensitive to perturbations by greenhouse gases than current global models predict, and even the highest warming predictions would underestimate the real change we could see.“
Another day, another study that suggests we face climate impacts on the high end of current projections.
Contrary to the observation-free wishful thinking of the disinformers and confusionists, the best scientific evidence is, “Clouds Appear to Be Big, Bad Player in Global Warming” “” an amplifying feedback (sorry Lindzen and fellow deniers). That was how Science described one major 2009 study.
A new paper in Journal of Climate, (subs. req’d), reconciles observed cloud variations in the tropical and subtropical eastern Pacific region with climate models — and finds that, if their results are correct, “they provide support for the high end of current estimates of global climate sensitivity.”
Here are excerpts from the University of Hawaii news release, “Study could mean greater anticipated global warming” (the source of the quote above):
Current state-of-the-art global climate models predict substantial warming in response to increases in greenhouse gases such as carbon dioxide. The models, though, disagree widely in the magnitude of the warming we can expect. The disagreement among models is mainly due to the different representation of clouds. Some models predict that global mean cloud cover will increase in a warmer climate and the increased reflection of solar radiation will limit the predicted global warming. Other models predict reduced cloudiness and magnified warming. In a paper that has just appeared in the Journal of Climate, researchers from the University of Hawaii Manoa (UHM) have assessed the performance of current global models in simulating clouds and have presented a new approach to determining the expected cloud feedbacks in a warmer climate.
Lead author Axel Lauer at the International Pacific Research Center (IPRC) at UHM notes, “All the global climate models we analyzed have serious deficiencies in simulating the properties of clouds in present-day climate. It is unfortunate that the global models’ greatest weakness may be in the one aspect that is most critical for predicting the magnitude of global warming.”
To study the clouds, the researchers applied a model representing only a limited region of the atmosphere over the eastern Pacific Ocean and adjacent land areas. The clouds in this region are known to greatly influence present climate, yet current global models do poorly in representing them. The regional model, developed at the IPRC, successfully simulates key features of the region’s present-day cloud fields, including the observed response of clouds to El Nino. Having evaluated the model’s simulation of present-day conditions, the researchers examined the response of simulated clouds in a warmer climate such as it might be in 100 years from now. The tendency for clouds to thin and cloud cover to reduce was more pronounced in this model than in any of the current global models.
We continue to learn about the dangerous positive carbon-cycle feedbacks that threaten to amplify the impacts of human-caused GHGs:
Study: Water-vapor feedback is “strong and positive,” so we face “warming of several degrees Celsius”
The best evidence is that the climate is now being driven by amplifying feedbacks “” see, most notably:
- The defrosting of the permafrost
- The drying of the Northern peatlands (bogs, moors, and mires).
- The destruction of the tropical wetlands
- Decelerating growth in tropical forest trees “” thanks to accelerating carbon dioxide
- Wildfires and Climate-Driven forest destruction by pests
- The desertification-global warming feedback
And let’s not even get started on destabilizing and venting the Vast East Siberian Arctic Shelf methane stores : NSF issues world a wake-up call: “Release of even a fraction of the methane stored in the shelf could trigger abrupt climate warming.”
UPDATE: See also Lindzen debunked again: New scientific study finds his paper downplaying dangers of human-caused warming is “seriously in error”, Trenberth: The flaws in Lindzen-Choi paper “have all the appearance of the authors having contrived to get the answer they got.”