Climate warming is causing a decrease in snowfall and increase in rainfall at high altitudes in the Northern Hemisphere. Now a study published in Nature has predicted an increase in the risk of extreme rainfall events.
The intensity and frequency of extreme precipitation events is expected to increase as global warming continues to affect the planet. Of particular concern are extremes in rainfall, which often cause more damage than similar snowfall events due to their instantaneous runoff, increasing the risk of floods, which can cause infrastructure damage and landslides. Precisely how increases in global temperature will affect extreme rainfall events remains unclear.
To assess how climate change might be driving a shift in precipitation patterns, researchers from Lawrence Berkeley National Laboratory, Berkeley, California combined data from climate observations from between 1950 and 2019 with future projections, up to 2100, taken from Earth system models. Their results suggest that warming is causing an increase in rainfall extremes within regions of high elevation in the Northern Hemisphere, particularly in regions usually dominated by snowfall.
On average, the intensity of extreme rainfall events is estimated to increase by 15% per 1 degree C of warming. These patterns are seen both in the historical observations and future projections. The estimated rate of increased rainfall in high altitudes is approximately double that of low altitudes, highlighting the increased vulnerability of mountainous regions to extreme precipitation. They utilised both a climate reanalysis dataset and future model projections to show that the amplified increase is due to a warming-induced shift from snow to rain. “Our findings pinpoint high-altitude regions as ‘hotspots’ that are vulnerable to future risk of extreme-rainfall-related hazards, thereby requiring robust climate adaptation plans to alleviate potential risk,” they write.
“The implications of our results center around the importance of developing sound climate adaptation plans to protect the natural and built environments and the 26% of the global population living in or directly downstream of mountainous regions. It is also important to recognize that the amplification of rainfall extremes is likely to be associated with a decrease in snowfall extremes owing to the transition from snow to rain. Such a decrease in snowfall extremes is consistent with previous work, and it presents an additional layer of complexity that needs to be taken into account in developing adaptation and mitigation strategies,” they note.
