The Contribution of Climate Change to Increasing Extreme Ocean Warming Around Japan

Abstract

Global warming is attributed to human activities that potentially cause record warm sea surface temperatures (SSTs) worldwide. However, to what extent climate change has altered discrete extreme ocean warming (EOW) around Japan remains unclear. Here, we show the impact of global warming on EOW events (high SSTs less frequent than once per 20 years at the preindustrial level) surrounding Japan in each calendar month for 1982–2022 using climate models. In contrast to the gradually increasing occurrences of EOW events, the most frequent events occurred in approximately 1998 and the mid-2010s, especially in southern Japan. We found climate change was not yet dominant in the 1998 events but has multiplied the occurrence probability of most events by at least twice since 2000. Furthermore, we estimated that the possibility of the future normal climate exceeding record high SSTs can be sharply reduced by limiting global warming from 2°C to 1.5°C.