Many of the most important impacts of global warming will probably not be the actual changes in temperature, but the associated changes in hydrology. A warmer atmosphere can contain much more moisture, which we expect to make flash flooding more likely, but the global-mean rainfall is thermodynamically constrained to increase more slowly, so we expect a general tendency to increased drought as well.

Yet we cannot constrain any of this well on the more local scales where it matters, because precipitation has much smaller scales and stronger gradients than temperature, and is much more dependent on smaller-scale circulation and topography, and the agreement between different GCMs (General Circulation Models, the most detailed and physically-based models of climate) is correspondingly poorer.

Objectives of the HYDRA project

HYDRA aims to attack this uncertainty by:

  • creating, and making generally available, a uniquely large sample of physically diverse GCM simulations at higher resolution than most existing ones (thanks to the volunteers of climateprediction.net)
  • avoiding some uncertainties by looking at the climate change associated with a given warming, not a given date - we do not know when the world will warm by 2K (kelvin) in the global mean (corresponding typically to about 3K over land), but as that is the lowest warming there is any political discussion of limiting to, we can be fairly sure we will at least get close to it
  • aiming to understand the physical constraints on climate change, not just looking at the statistics of these simulations
  • adapting techniques that are standard in neuroscience to allow for GCMs often “doing the right thing in the wrong place”
  • examining much more exhaustively than has previously been possible the uncertainties in climate response due to uncertainties in how to model land surface effects.

Key project members of HYDRA

Principle Investigator: Prof Myles Allen

Co-Principal Investigators:

Professor Peter Cox, University of Exeter

Dr Hugo Lambert, University of Exeter

Dr Chris Huntingford, Centre for Ecology and Hydrology

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