TP19

Understanding why planetary atmospheres look the way they do today - and reconstructing the evolutionary pathways that brought them to their present states - is one of the most compelling questions in modern planetary science. This session adopts a comparative planetology perspective, bridging solar system bodies and exoplanet populations through
the lens of atmospheric evolution, investigated through observations, modelling, and mission-driven science.

We welcome contributions addressing the long-term evolution of atmospheres across all planetary types. In the inner solar system, Venus and Mars stand as striking cases of evolutionary divergence from Earth. Contributions on the Venus climate system and its long-term history are particularly encouraged, from photochemistry and cloud dynamics to the
transformative science expected from ESA's EnVision and its VenSpec suite.

In the outer solar system, Titan's organic-rich and seasonally evolving atmosphere offers a unique window into photochemical complexity and long-term change, with new observational and modelling efforts building on the Cassini legacy. The gas and ice giants - characterized with unprecedented detail by JWST, Juno, and the forthcoming JUICE mission - further enrich this comparative picture; ice giant atmospheres in particular represent a frontier for solar system science and an archetype for the most abundant planetary class in the galaxy, with the scientific case for a Uranus mission gaining momentum under NASA's Decadal Survey and ESA's Voyage 2050 framework.

Finally, broader comparative studies linking solar system atmospheric structure and chemistry to the growing population of exoplanets accessible to spectroscopic characterization are warmly welcomed. This includes contributions on atmospheric escape and its demographic imprints on exoplanet populations - from the radius valley and the Neptune desert to observations of young systems caught in the act of losing their envelopes. Both observational and modelling contributions are welcome, as well as cross-disciplinary studies connecting solar system and exoplanet atmospheric science through laboratory measurements, modeling and/or observations.

*This session is supported by the International Commission on Planetary Atmospheres and their Evolution (ICPAE), part of the International Association of Meteorology and Atmospheric Sciences (IAMAS).