18 Feb (CLIM) Simpson, Water Vapor Trends

Isla Simpson, National Center for Atmospheric Research (NCAR)

A global discrepancy in near surface water vapor trends between models and observations

Wed, 18 Feb, 1:30pm Innovation Hall 131 and via Zoom (for link, email bklinger@gmu.edu)

Host: Aahelee Simpson

As the planet warms, it is expected that atmospheric water vapor would rise given the dependence of the atmospheric water vapor holding capacity on temperature. Indeed, in observations over the last four decades, over many parts of the world, this is what has happened. However, over arid and semi-arid regions of the world, near surface atmospheric water vapor has remained fairly constant in the observational record, in stark contrast to the behavior of Earth System Models that are used for long-term climate projections, which suggest water vapor should have risen. This discrepancy represents a significant problem in our models’ ability to represent hydrological processes, or potentially issues with the observational record (or both). If it is a problem with our model representation, then it has major implications for our ability to predict the future of the hydroclimate and associated aspects such as wildfire risk.