As supercomputers become more powerful, the climate of the future is coming into sharper and sharper focus. In this case, it’s the climate of Europe and the North Atlantic, recently elucidated by a new, high-resolution model powered by supercomputers and run by scientists from the Barcelona Supercomputing Center (BSC) in collaboration with the UK’s Met Office.

“IPCC [Intergovernmental Panel on Climate Change] models project a likely increase in winter precipitation over northern Europe under a high-emission scenario,” reads the paper, published in the May issue of Environmental Research Letters. “These projections, however, typically rely on relatively coarse ~100 km resolution models that can misrepresent important processes driving precipitation, such as extratropical cyclone activity, and ocean eddies.”

These researchers’ climate model, by way of contrast, was a “pioneering” atmospheric model operating at a 50 km resolution coupled with a similarly high-resolution ocean model. To run this intensive model, the researchers used the in-house supercomputing at the Barcelona Supercomputing Center: specifically, its MareNostrum 4 supercomputer, which delivers 6.5 Linpack petaflops and ranked 42nd on the most recent (but soon to be updated) Top500 list.

The result: “[the] model … projects a substantially larger increase in winter precipitation over northwestern Europe by mid-century than lower-resolution configurations. For this increase, both the highest ocean and atmosphere model resolutions are essential … all recent IPCC climate projections using traditional ~100 km resolution models could be underestimating the precipitation increase over Europe in winter and, consequently, the related potential risks.”

The IPCC reports are typically the gold standard of climate research, and are used to guide policy around the world for years after their release. For the BCS researchers, the strong differences between their results and those published by the IPCC are a cause for serious reexamination.

“These models present a future that is quantitatively different from what the traditional models have been suggesting, with regions like the Gulf Stream experiencing extraordinary warming,” said Pablo Ortega, co-lead of BSC’s Climate Prediction Group. “But more importantly, they also anticipate important changes in the behaviour of the ocean circulation with implications for the weather conditions that we experience in our daily lives”. 

The cause of the projected rainfall increase, of course, was the anticipated 7°C warming by 2050 (using a baseline of the mid-20th century). “Such a strong warming is behind all the changes in precipitation we see over Europe,” said Eduardo Moreno-Chamarro, a research scientist in BSC’s Climate Prediction Group and lead author of the study. “The warming pumps heat from the ocean into the atmosphere, favoring the formation of low pressure systems over the North Atlantic. These lows are ultimately responsible for bringing more precipitation over northwestern Europe.”

To learn more, read the paper here.