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Clouds, Circulation and Climate Sensitivity

Limited understanding of clouds is the major source of uncertainty in
climate sensitivity, but it also contributes substantially to GC4 sat clouds 10cmpersistent biases in modelled circulation systems.
How do clouds couple to circulations in the present climate?
How will clouds and circulation respond to global warming or other forcings?
How will they feed back on it through their influence on Earth's radiation budget?

As one of the main modulators of heating in the atmosphere, clouds control many other aspects of the climate system... read the white paper

GC4 anvil ISS016-E-27426 lrg 10cmThe WCRP Grand Challenge on Clouds, Circulation and Climate Sensitivity is articulated around five main initiatives, complementary and coupled to each other:
- Climate and hydrological sensitivity
- Coupling clouds to circulations
- Changing patterns
- Leveraging the past record
- Towards more reliable models













 Bony etal ngeo15 GC cover


S.Bony, B. Stevens, D. M. W. Frierson, C. Jakob, M. Kageyama, R. Pincus, T. G. Shepherd, S. C. Sherwood, A. P. Siebesma, A. H. Sobel, M. Watanabe & M. J. Webb (2015): Clouds, circulation and climate sensitivity. Nature Geoscience 8, 261–268 (2015) doi:10.1038/ngeo2398


As the Earth warms, new questions arise concerning how clouds and circulation systems respond. These questions are both intellectually fascinating and societally important. Will cloud systems organize in entirely different ways in a warmer climate, so as to decrease the warming from CO2? Will shifts in midlatitude storms, or monsoon systems, reshape nations and societies in the future? Does the nature of tropical convection - still one of nature's most mysterious processes - hold the key for the pace of warming?


Answers to these questions are crucial for societies grappling with how to design effective policies for dealing with climate change. Because of technological advances in supercomputing and observational networks, they are also becoming more accessible to researchers.


In a 2015 article featured in Nature Geoscience, Sandrine Bony and Bjorn Stevens describe a new initiative to address these challenges by describing what they believe to be four of the most important questions that would benefit from coordinated scientific action. Bjorn Stevens: "For a long time the scientific community has focused on understanding how much Earth's average temperature will rise for a given input of CO2. We have been slow to realize that to craft effective adaptation policies on the local, regional and national scale it will be important to understand how circulation systems will change with warming. In awakening to this question we have also come to appreciate that changes in circulation systems are closely coupled to how clouds and radiative transfer interact with those systems."