Wetter winters across northern Europe and drier winters across southern Europe are expected towards the end of this century. But the scale of these changes may be underestimated by some climate models, which currently operate at low-resolutions.
Tests using a higher-resolution climate model, which has the ability to take a closer look and capture weather-scale processes, shows stronger and more reliable changes in winter with climate change.
How will climate change impact the jet stream and Europe’s winters?
The North Atlantic jet stream steers extratropical storms towards Europe, storms which account for around 70% of our rain in winter. The wettest winters in Europe, such as in 2013/14, often occur because of this westerly conveyor belt of storm systems.
Climate models (at all resolutions) show that with climate change fewer storms will make landfall over southern Europe, but more will steered to move across northern Europe. Crucially, new research shows the magnitude of these climate change consequences rise significantly when the resolution of the models is increased.
Are these high-resolution projections for future European winters more trustworthy?
Climate models break down the Earth’s atmosphere into pixels, or three-dimensional grid cells. With a low number of large grid cells (each typically 100-200 km2 wide), weather systems in climate models can appear pixelated and not very realistic.
Lower-resolution climate models may have in the past underestimated atmospheric responses to climate change, such as the strength and direction of the jet stream that steers storms towards Europe.
Developments in high-performance computing have enabled scientists to shrink the size of a climate model’s grid cells (to roughly 25km), increase their number, and capture air flows, weather processes and other aspects of atmospheric variability in more detail.
For Europe, high-resolution modelling, which simulates the large-scale westerly jet stream and weather systems like extratropical storms more credibly, should provide more reliable future climate projections.
More investigations like the research study, led by Dr Alexander Baker (NCAS scientist, based at the University of Reading), will offer greater insight into how higher-resolution models may bring the picture of Europe’s future winters into sharper focus.