Research press release





今回、Marshall Burkeたちの研究グループは、過去のデータを国内レベルの気候予測および社会経済予測と組み合わせて、今後のさまざまなレベルの温暖化に伴う経済的損害を評価した。その結果、21世紀末までに気温上昇を摂氏1.5度に抑えられた場合には、摂氏2度の場合と比べて全球的な経済的損害が少なくなる確率が75%であり、全球的な経済的便益が20兆ドルを超える確率が60%とされた。また、Burkeたちは、世界人口の90%に相当する全世界の国々の71%(3大経済大国の米国、中国、日本を含む)で気温上昇を摂氏1.5度に抑えられた場合、経済的損害が少なくなる確率が75%で、貧困国で経済的便益が最も大きくなることを明らかにした。


The global and country-specific economic impacts of limiting global warming to 1.5 degrees Celsius rather than to 2 degrees Celsius above preindustrial levels by 2100 are quantified in Nature this week. The study suggests that meeting the 1.5 degrees Celsius goal by the end of the century instead of the more common 2 degrees Celsius target is likely to yield considerable economic benefits - potentially saving more than 20 trillion US dollars.

Achieving the ambitious Paris Agreement climate goal to limit global warming to 1.5 degrees Celsius above preindustrial levels will require substantial investment in mitigation efforts. Understanding what, if any, economic benefits may arise from meeting the goal is thus necessary to inform decisions about whether or how to pursue the target.

Marshall Burke and colleagues combine historical data with national-level climate and socioeconomic projections to assess the economic damages associated with different levels of future warming. They estimate that by the end of the century, there is a 75 per cent chance that limiting warming to 1.5 degrees Celsius would reduce economic damages relative to 2 degrees Celsius, and a 60 per cent chance that these benefits would exceed 20 trillion US dollars globally. They also find that 71 per cent of countries - including the three largest economies (the USA, China and Japan) and representing 90 per cent of the global population - have a 75 per cent chance of experiencing reduced economic damages at 1.5 degrees Celsius, with poorer countries benefiting most.

The authors caution that the approach is subject to various uncertainties, and factors such as abrupt changes in extreme events, including large-scale sea-level rise, or economic growth rates could affect the impacts of a warming climate. Nonetheless, the findings suggest that achieving the 1.5 degrees Celsius target is likely to reduce economic damages, while there is a strong possibility that failing to meet the 2 degrees Celsius target would increase damages substantially, perhaps by more than 15 per cent of global economic output.

doi: 10.1038/s41586-018-0071-9

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