Research press release


Scientific Reports

Climate science: Do cool Alpine summers open the floodgates?



今回、Lukas Glurたちは、スイス・アルプス地方の10か所の湖の堆積物を調べて、放射性炭素分析による年代決定を行った。湖沼堆積物には、過去の洪水事象がそれぞれ独自の堆積層として残っているので、洪水活動が正確に反映されている。Glurたちは、冷夏の時に洪水が最も頻繁に起こる傾向を明らかにし、こうした高降水量と低温の同時発生のきっかけが大西洋と地中海上の低気圧の進路に緯度方向の変化が生じることだと考えている。今回の研究で示された古気候学的見方は、全球的な気候変動が異常気象事象に影響を及ぼす過程の解明に寄与し、今後の気候温暖化における洪水リスクの評価を改善できる可能性がある。

A comprehensive reconstruction of intense precipitation events in the European Alps over a 2,500-year period suggests that periods with a high flooding frequency tend to coincide with cool summer temperatures. The research, published in Scientific Reports this week, could help to improve projections of weather extremes under climate change.

Mean summer temperatures in Central Europe are projected to increase under global climate change, while summer precipitation totals are expected to decrease. Potential enhanced flood occurrence could also increase the risk to settlements, infrastructure, and human lives in the affected regions, including in the Alps. However, the frequency of climate extremes, such as intense precipitation events, is harder to predict.

Lukas Glur and colleagues examined sediment deposits from ten lakes in the Swiss Alps, which they dated using radiocarbon analysis. Lake sediments offer an accurate reflection of past flood activity, as they record individual events as distinct sediment layers. The authors show that floods tend to occur more frequently during cool summers, and they suggest that this wet-cold co-occurrence may be triggered by latitudinal shifts of Atlantic and Mediterranean storm tracks. The palaeoclimate perspective offered by the study could contribute to a better understanding of how global climate change might affect extreme weather events and improve flood-risk assessment in a future warmer climate.

doi: 10.1038/srep02770

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