Research press release


Nature Climate Change

Sierra Nevada’s record low snowpack unprecedented in 500 years



今回、Valerie Trouetたちは、冬季の降水量を反映する樹木年輪時系列と冬季の気温を反映する別の代理指標を組み合わせて、4月1日時点のシエラネバダ山脈の冬季雪塊量を過去500年間にわたって再現した。その結果、2015年の記録的に少ない雪塊量が異常な現象であり、その再来周期が高地で95年、冬の温暖化が雪塊量に及ぼす影響が顕著な低地で1,000年と推定された。


The snowpack in California’s Sierra Nevada mountain range is the lowest it has been in the last five centuries, according to a study published online in Nature Climate Change. This snowpack decline, which is likely to impact agricultural and urban water supplies, and could affect hydroelectric power and increase the risk of wildfires, is linked to and confirms the severity of the California drought.

Snow accumulates in the Sierra until April, when it starts to melt due to decreased precipitation and higher temperatures. The instrumental record shows the 1 April snowpack in Sierra Nevada in 2015 was 5% of the historical average (from 1951 to 2000), but a longer-term historical record in which to place this recent decline is not yet available.

Valerie Trouet and colleagues reconstructed the 1 April winter snowpack conditions in the Sierra Nevada for the last 500 years by combining a tree-ring series that reflects winter precipitation with another proxy that reflects winter temperature. They find that the record low snowpack in 2015 is exceptional, with a probable return period of once every 1,000 years at lower elevations, where the effect of warm winter temperatures on the snowpack is more pronounced; while at higher elevations the return period is 95 years.

These findings highlight the critical condition of the state’s primary natural water storage system.

doi: 10.1038/nclimate2809


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