Future projections

Projecting climate change is a very complex and ever-evolving science. Previously, projections using SRES scenarios (scenarios linked to specific combinations of socioeconomic and technological developments) were published by C4I in 2008. Scenarios were generated for three different time periods of this century: the 2020s (2010 – 2039); the 2050s (2040 – 2069); and the 2080s (2070 to 2099). 

Met Éireann's "Ireland's Climate: The Road Ahead" (2013) used the new Representative Concentration Pathways (RCP) scenarios. These focused on radiative forcing – the change in the balance between incoming and outgoing radiation via the atmosphere caused primarily by changes in atmospheric composition – rather than being linked to any specific SRES scenarios. Currently, a new set of climate projections using radiative forcing techniques is being processed at the Irish Climate Analysis and Research Units (ICARUS) in NUI Maynooth (http://icarus.nuim.ie), representing yet another step forward in climate projection science.

The output of Global Climate Models (GCMs) used to generate projections have a horizontal resolution of between 250 and 600 km. This scale is too coarse for assessing the impact of climate change at a local level. In the diagram below (which gives an indication of the scale and complexity at which GCMs operate), Ireland is represented by just two grid squares.

This is of little use to policy makers and researchers, who need data with a much finer geographical scale to assess aspects such as the future flow regime of a river or the future distribution of an endemic species within a small geographical range. To facilitate such studies, downscaling of GCM outputs is employed. Two plausible methods of downscaling are dynamical downscaling and statistical downscaling. In ICARUS, statistical downscaling was employed to generate future climate change data for Ireland.