Shaping tomorrow's world: the climate

Faced with the extreme complexity of the mechanisms that play a role in climate change, X's researchers will have to rise to some serious scientific challenges. One of them concerns the monitoring of greenhouse gas emissions, which is essential to be able to predict the evolution of the climate. To monitor these emissions, researchers at Polytechnique are working on a technique using observation satellites, whose importance has been recognized by the space agencies for a decade or more. X's Dynamic Meteorology Laboratory has thus begun to estimate atmospheric CO2 concentrations from space. Thanks to its recognized expertise in radiation transfer, the laboratory was selected by the CNES, the French national space agency, to carry out different space missions: IASI-NG, Merlin and MicroCarb. Another issue concerns the modeling of the atmosphere for simulation purposes. Every year, a hole forms in the ozone layer over Antarctica in spring and then closes up again in autumn. And every winter, a powerful vortex forms there and isolates air masses in the polar night whose particularly cold temperatures contribute to the destruction of the ozone in spring. All the atmospheric models present a bias in the polar region, simulating temperatures that are too cold and a vortex that is too persistent. To explain these biases, a team at X's Dynamic Meteorology Laboratory is studying the internal gravity waves, oblique movements in the air equivalent, within the atmosphere, to the waves on the surface of a lake or the sea. To do this, the researchers have conducted measurement campaigns using about forty super-pressure balloons flying in the lower stratosphere, capable of tracking the air masses and measuring small-scale physical processes. It is therefore possible to better understand and describe the internal gravity waves, in particular above the Southern Ocean. These results have enabled the researchers to reset the parameterization of gravity waves in the laboratory's atmospheric model. The changes have led to a striking improvement in simulations of the polar atmosphere. Other work being done by the Dynamic Meteorology Laboratory includes a team working on models to predict the evolution of climate change based on calculations on a digital layer representing the atmosphere. Applied to the region around the Mediterranean, these models show that droughts will increase in number and severity. The laboratory's climate projections allow it to work on innovative solutions to minimize the impact of the climate in the general deterioration of living conditions in the Mediterranean region.