Attribution of the 2015 record high sea surface temperatures over the central equatorial Pacific and tropical Indian Ocean

In Hong Park, Seung-Ki Min, Sang-Wook Yeh, Evan Weller, Seon Tae Kim

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Abstract

This study assessed the anthropogenic contribution to the 2015 record-breaking high sea surface temperatures (SSTs) observed in the central equatorial Pacific and tropical Indian Ocean. Considering a close link between extreme warm events in these regions, we conducted a joint attribution analysis using a fraction of attributable risk approach. Probability of occurrence of such extreme anomalies and long-term trends for the two oceanic regions were compared between CMIP5 multi-model simulations with and without anthropogenic forcing. Results show that the excessive warming in both regions is well beyond the range of natural variability and robustly attributable to human activities due to greenhouse gas increase. We further explored associated mechanisms including the Bjerknes feedback and background anthropogenic warming. It is concluded that background warming was the main contribution to the 2015 extreme SST event over the central equatorial Pacific Ocean on a developing El Niño condition, which in turn induced the extreme SST event over the tropical Indian Ocean through the atmospheric bridge effect.

Original languageEnglish
Article number044024
Number of pages9
JournalEnvironmental Research Letters
Volume12
Issue number4
DOIs
Publication statusPublished - 21 Apr 2017

Keywords

  • anthropogenic forcing
  • attribution
  • central equatorial Pacific Ocean
  • sea surface temperature
  • tropical Indian Ocean

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