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

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 degrees C to 1.5 degrees C.

Automated summary

This study used climate models to investigate the impact of climate change on extreme ocean warming events around Japan. The research found that extreme ocean warming events have been increasing in recent years, especially in southern Japan. Climate change has significantly increased the probability of these events since 2000. Furthermore, the study concluded that limiting global warming to 1.5 degrees Celsius can greatly reduce the likelihood of future normal climate exceeding historical record high sea surface temperatures.