B1 Intermediate · 433 words · 3 min read

World's Oceans Hit Record-High Temperatures as El Niño Builds

A record daily average of just over 21 degrees Celsius, driven by climate change plus El Niño, threatens coral reefs, fisheries and coastal communities — and gives storms extra fuel

The surface of the world's oceans has reached its highest temperature ever recorded, with a global daily average of just over 21 degrees Celsius, according to climate monitoring data reported by the Associated Press and other news organisations. Scientists describe the reading as a warning sign for the health of the whole planet.

The record is the result of two forces working together. Human-caused climate change has been heating the oceans for decades — the seas have absorbed about 90 percent of the extra heat trapped by greenhouse gases. On top of that long-term trend, a strong El Niño is developing in the Pacific. El Niño is a natural pattern that appears every few years and temporarily warms huge areas of the ocean, pushing global temperatures to new peaks.

The clearest victims of marine heat are coral reefs. When water stays unusually warm for weeks, corals expel the tiny algae that feed them and give them colour, turning ghostly white — a process called bleaching. Bleached corals are not gone, but they are weak, and repeated heatwaves can destroy a reef that took centuries to grow. Because reefs shelter about a quarter of all marine species, the damage spreads through the whole food chain.

Fish feel the heat too, and many respond by moving towards cooler water nearer the poles. That matters for people: billions of people around the world rely on the sea for a large part of their protein, and fishing communities from West Africa to Southeast Asia depend on catches that may shrink or move away. Scientists also warn that warmer surface water provides extra energy for hurricanes and typhoons, which can make the strongest storms more intense and rainier — hard news for coastal communities already dealing with rising seas.

The oceans cover about 70 percent of the Earth, produce a large share of the oxygen we breathe and store enormous amounts of carbon, so a record-warm ocean is not only a problem for divers and fishers. It slowly reshapes weather patterns, food prices and coastlines everywhere.

Researchers stress that the trend, not one hot day, is the real story — and that the trend can still be bent. Burning less coal, oil and gas would slow the warming; marine protected areas give reefs and fish a better chance to recover; and accurate daily measurements, from satellites and thousands of ocean buoys, help the world see clearly what is happening. As one climate scientist put it, the ocean has been protecting us for decades by soaking up heat. Now, they argue, it is our turn to protect the ocean.

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