The EUREC4A (Elucidating the role of cloud-circulation coupling in climate) project focused on two fundamental questions of climate and atmospheric science: How sensitive is the Earth’s surface temperature to an increase in atmospheric greenhouse gases? and What role does the organization of the atmosphere into rain bands, cloud clusters or storms play in climate? Answering these seemingly different questions is important to improve estimates of the rate and magnitude of global warming over the next decades, and to better understand and predict the evolution of weather and climate at the regional scale.
One of the main sources of uncertainty in the Earth’s climate sensitivity to greenhouse gases is the response of clouds to changes in their environment, particularly the response of low-level clouds that occur in the trade wind regions. To reduce this uncertainty, we designed and led (with B. Stevens, in collaboration with European, US and Caribbean teams) the first airborne field campaign specifically designed to test hypothesized mechanisms whereby changes in trade wind clouds with global warming act to amplify this warming, a positive feedback which would increase Earth's climate sensitivity. Beyond this specific objective, the field campaign aimed to better understand the physical processes through which trade wind clouds interact with their environment. The EUREC4A field campaign took place over the tropical Atlantic near Barbados in January and February 2020.
In parallel, we have investigated how clouds and convection organize themselves in space, forming clumps or patterns, and explored the role this spatial organization might play in climate. In doing so, we sought to address one of the main questions of the World Climate Research Programme’s Grand Challenge on Clouds, Circulation and Climate Sensitivity. In particular, we examined the role of cloud organization in the Earth's radiation budget, large-scale atmospheric circulation, and extreme precipitation. We also studied how anvil clouds, which form in the upper atmosphere and can cover large areas, respond to climate perturbations or natural or anthropogenic origin.
The project addressed these challenges with a team of PhD students, post-docs and engineers, in collaboration with a number of collaborators, and by exploiting the synergy between models and observations on a wide range of scales.
