a space mission aims to better understand the role of clouds in climate change

The objective is to determine all the physical parameters of the clouds. If their influence on the weather is well known, their impact on the climate is much less so.



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Global warming is changing the distribution of clouds, May 26, 2024. (ROBERT MICHAEL / DPA)

This is a unique space mission. A satellite will leave, during the night of Tuesday May 28 to Wednesday May 29, to scan the clouds from space. The objective is to better understand their role in climate change. Takeoff is scheduled for around 12:30 French time. This satellite, called “Earth Care”, will take off aboard a SpaceX rocket from California.

This mission, which is the result of a collaboration between the European Space Agency and Japan, promises to be complex but revolutionary. This satellite weighing more than two tonnes carries four cutting-edge instruments on board, which have never before worked together. There is a LiDAR (Light Detection And Ranging) , a radar, a multispectral imager, a broadband radiometer… So many instruments, which, used simultaneously, will be able, at an altitude of 400 km, to determine all the physical parameters of the clouds. Whether it is their internal structure, their composition in water droplets, ice, and solid dust. These devices will also record the solar radiation reflected by these clouds, and how they capture heat.

This is information eagerly awaited by the scientific community, because the role of clouds on the climate remains poorly understood. We know their influence on the weather, but less their long-term impact on the climate. However, clouds, depending on their size and altitude, have the particularity of having a sometimes cooling and sometimes warming effect on the earth.

Very white and very bright clouds, like large cumulus clouds, have more of a parasol effect. They reflect the sun’s radiation back into space, and this helps cool our atmosphere. But other clouds, like cirrus clouds which are very thin, allow solar radiation to pass through and, on the contrary, play a covering role. They capture and retain heat.

This satellite mission aims to better understand this contrasting effect of clouds. This information is all the more valuable as global warming is changing the distribution of clouds. As they are formed of water and dust droplets, their presence is influenced by the quantity of water, which evaporates from the land and oceans, but also by suspended sediments, by pollen, or particles fines from pollution. So many factors are changing under the influence of global warming and human activities.

The clouds are thus in the process of changing, hence the importance of better understanding their functioning, to anticipate the climate models of the future.

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