Earth’s ocean temperatures have risen so fast in recent weeks that one indicator shows surface waters have already reached their highest temperatures on record – a worrisome sign ahead of a predicted El Niño climate pattern that could further accelerate planetary warming.

Around mid-March, ocean-temperature monitoring data shows that average surface water temperatures surpassed about 70 degrees Fahrenheit around the globe, excluding polar waters, for the first time since at least 1981, when the data set originated. That is warmer than what scientists observed at this time of year in 2016, when a strong El Niño drove the planet to record warmth.

The conditions are surprising and alarming to some meteorologists and climate scientists, although they say it is far too early to assume that a record year of oceanic or planetary warmth is ahead.

The data suggests, at least, that the planet, already beset with extreme warmth, is entering an expected stretch of accelerating heat.

The ocean temperature observations coincide with the release Monday of a definitive report from the United Nations Intergovernmental Panel on Climate Change asserting that drastic action is needed to slow global warming that has already irrevocably harmed ecosystems and communities. Earth’s temperatures are on a clear upward trajectory, already rising by at least 2 degrees Fahrenheit since humans began burning fossil fuels to power industry.

The ocean data comes from a network of buoys, ships and satellites from which the National Oceanic and Atmospheric Administration collects daily data on the first few meters of ocean depth. The database – known as the NOAA ¼ Degree Daily Optimum Interpolation Sea Surface Temperature – shows a steady warming trend in sea surface water since the 1980s, with each of the past several years of data ranking well above all older data.

And it shows that 2023 is on pace at least to be yet another year among the warmest on record for the oceans. (Sea surface temperatures can vary according to weather, but across all depths, Earth’s oceans are gradually warming each year as they absorb more and more of the planet’s heat.)

Climate scientists expect that 2023 will be among the planet’s warmest years on record and think there is a 65 percent chance it ranks in the top five. Last year was Earth’s sixth-warmest year on record..