Jun 6, 2024 - Energy & Environment

Global oceans see 14th-straight month of record-shattering heat

A line chart that shows the global daily average sea temperature since 1981. Since Apr. 1 2023, each day has broken high temperature records.
Data: climatereanalyzer; Chart: Axios Visuals

As large parts of the American Southwest bake in record heat, new data shows that May extended the record streak for global ocean temperatures as well.

Why it matters: The past 14 months have featured surprisingly large temperature anomalies across the world's oceans, with widespread and damaging marine heat waves, the Copernicus Climate Change Service found.

The big picture: The data released Thursday by the European Commission agency bolsters other climate information that came out the day before, showing the world's oceans have been roasting at unprecedented temperatures since the first half of 2023.

  • Even with a La Niña event developing in the equatorial tropical Pacific Ocean, May still set a record for high ocean temperatures.
  • The ocean records are perhaps more significant, and unsettling, to climate researchers than recent air temperature milestones.
  • The vast majority, or about 91%, of the extra heat trapped by greenhouse gas emissions from burning fossil fuels, cutting down forests and other activities is going into the sea, which warms slowly over time.
  • Record warm temperatures in the North Atlantic Ocean Basin, among other factors, have meteorologists concerned about a historically active hurricane season.

By the numbers: On Wednesday Copernicus showed that May was the 12th consecutive month to set a monthly global average temperature record, and 11th straight month to exceed a key Paris Agreement temperature target.

Between the lines: The news comes as parts of Asia, Mexico and Central America, and now the Southwestern U.S. have baked from withering heat waves. Monthly and all-time high temperature records have been set in numerous cities and countries around the world.

  • It also comes as actions to limit climate change has been crowded out on the international agenda by armed conflicts, election campaigns and other factors.

Ocean heat also strongly affects conditions on land, since warmer waters evaporate more moisture into the atmosphere, helping to supercharge storm systems.

  • In addition, record warm water near Florida has helped drive persistently record warm conditions on land there, and a similar dynamic has played out elsewhere around the world.
  • Simply put: what happens in the oceans does not stay in the oceans.

Zoom in: According to CCCS, May's global average surface temperature came in at 1.52°C (2.73°F) above preindustrial levels.

  • This year has featured temporary leaps above the 1.5-degree target, beyond which the effects of global warming could spell the demise of low-lying island nations and other highly vulnerable regions.

What they're saying: "Until we reach net-zero global emissions the climate will continue to warm, will continue to break records, and will continue to produce even more extreme weather events," said Samantha Burgess, Copernicus' director, in a statement.

  • "If we choose to continue to add greenhouse gases to the atmosphere then 2023/4 will soon look like a cool year," she said.
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