気候変動：1851～2019年の大西洋における重大ハリケーンの変化傾向を評価する

Recent increases in the most intense Atlantic hurricanes (major hurricanes) may not be part of a century-scale change but reflect a rebound from minimal activity from the 1960s–1980s, according to a paper published in Nature Communications. However, the findings do not necessarily mean that climate change is not affecting the frequency or intensity of tropical cyclones. The authors suggest that climate variability and aerosol-induced hurricane reductions may have masked century-scale greenhouse-gas warming contributions to North Atlantic major hurricane frequency.

Tropical cyclones are expected to become more intense as sea surface temperatures increase. Atlantic major hurricanes have become more frequent since the 1980s, but it is not clear if this recent trend is a result of anthropogenic greenhouse gas emissions or reflects the variability of Atlantic hurricane activity. One of the key challenges in assessing this is that the observational record before 1972, when satellite data became available, might be incomplete, which would mean that earlier hurricane activity could be underestimated.

Gabriel Vecchi and colleagues analysed records of major hurricane activity in the Atlantic from 1851–2019. They used satellite records of hurricane tracks and characteristics from 1972 to 2019 to estimate the number of potentially missed storms in ship records from 1851 to 1971. Based on these estimations the authors find that major hurricane activity has increased over recent decades, but recent major hurricane frequency is not anomalous in the 20th century record, and reflects a recovery from a minimum in the 1960s–1980s. This reduction in activity may have been the result of human aerosol emissions inhibiting hurricane activity in combination with natural variability, the authors suggest. The updated estimates still show fluctuations on a year-to-year to decadal time scale, which indicates climate variability exerts a strong influence on Atlantic major hurricane activity.