Climate Change

North Atlantic marine heatwave ‘beyond extreme’

Higher sea surface temperatures also deplete the oxygen that aquatic animals need to survive

By DTE Staff
Published: Wednesday 05 July 2023

Scientists are alarmed not only by the fact that marine heatwaves are occurring so early in the season, but also because sea surface temperatures (SST) have risen 5 degrees Celsius above normal during June. This is the warmest they have been in more than 170 years for this time of the year. These temperatures are generally typical of August and September when oceanic waters are the warmest.

The National Oceanic and Atmospheric Administration of the United States said that heatwave conditions are likely to continue through August and there are 70-80 per cent chances that they will also continue till the end of the year.

Higher SSTs also deplete the oxygen that aquatic animals need to survive. While the temperatures are not lethal yet, continuing heatwave conditions might lead to critical marine species like oysters, kelp and algae dying.

In early June, thousands of dead fish washed up along the Texas gulf coast because of warming waters which was described as a ‘low dissolved oxygen event’. In 2021, when a heat wave was ravaging Canada, high sea surface temperatures killed half a billion shellfish on the country’s west coast.

While scientists agree that the underlying reason is high greenhouse gas emissions there could be several other reasons as well. The El Nino’s arrival coincided with the warming SSTs in the Atlantic ocean but it cannot be confirmed as the sole reason for the event.

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