As IMO Marine Environment Protection Committee members meet this week to review GHG emissions measures for shipping, they may have a new factor to consider: average ocean surface temperatures have just reached the highest level since recordkeeping began, according to NOAA’s sea surface temperature average index.
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The difference from the long-term average for this time of year is small in absolute terms – a bit more than one degree Fahrenheit – and it only reflects temperature at the surface, not in deeper waters. However, scientists warn that it is a sign of the long-term rising temperature trend in the world’s oceans, which have absorbed the overwhelming majority of the excess heat from recent decades of warming.
The latest record temperature occurs at the end of a three-year-long La Nina weather pattern in the Eastern Pacific. With an El Nino weather system expected to take over in the Pacific later this year, surface water temperatures in the Eastern Pacific region will rise, and global average sea surface temperature may further increase.
The NOAA data is the latest sign of rising temperatures in upper ocean waters. In 2022, ocean heat content in the upper 2,000 meters set a new record high, according to research published in Advances in Atmospheric Sciences, reflecting a pronounced warming trend dating back four decades.
The new record also coincides with the release of the latest Intergovernmental Panel on Climate Change report, the global scientific consensus study on greenhouse gas emissions and warming. Reiterating past guidance, this edition recommends “deep and rapid reductions in gross emissions of CO2” and other greenhouse gases, accompanied by carbon capture for hard-to-abate sectors like shipping.