Research press release


Nature Communications

Climate science: Glacier growth consistent with man-made climate change



今回、Andrew Mackintoshの研究チームは、氷河の成長や融解に影響を及ぼすさまざまな要因の役割を評価する地域スケールのエネルギー収支モデルを用いて、ニュージーランドの氷河の異常な挙動の原因を調べた。Mackintoshは、降水量の増加を原因に掲げる有力説が今回の解析によって裏付けられず、むしろニュージーランド地域での南風の頻度を高めた大規模大気波動の影響によるタスマン海とサザン・アルプス山脈での寒冷化が主な原因だったことを明らかにした。また、人為起源の温暖化を含めるモデルシミュレーションと含めないモデルシミュレーションの比較も行われ、1980~2005年のサザン・アルプス山脈の氷河氷の変化が人為的気候変動を一部反映していることが示唆されている。

A series of unusually cold years in the New Zealand region is responsible for the country’s advancing glaciers, according to a study published in Nature Communications this week. Although this sequence of climate variability and its effect on New Zealand glaciers is unusual on a global scale, it remains consistent with a climate system that is being modified by humans.

The world has experienced unprecedented global ice loss during the past three decades, which were the warmest decades since records began. Despite the warming conditions, some glaciers have grown: in New Zealand, at least 58 glaciers advanced between 1983 and 2008, yet the cause of this growth has been uncertain.

Andrew Mackintosh and colleagues investigate the cause of the anomalous behaviour of New Zealand’s glaciers using a regional-scale energy balance model, which assesses the role of various factors influencing glacier growth or melt. The authors show that the favoured theory - an increase in rainfall - was not supported by their analysis and that instead, cooling in the Tasman Sea and Southern Alps, influenced by large-scale atmospheric waves that encouraged southerly winds in the New Zealand region, was the primary cause. A comparison of model simulations that included and excluded human-induced warming also suggests that Southern Alps glacier ice changes between 1980 and 2005 partly reflects man-made climate change.

doi: 10.1038/ncomms14202

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