Top of the charts: Global ocean surface temperature hits record high | oceans

Global ocean surface temperatures have reached a record high since satellite records began, driving marine heatwaves around the world, according to US government data.

Climatologists said preliminary data from the National Oceanic and Atmospheric Administration (Noaa) showed that the average temperature at the surface of the oceans was 21.1 C since early April beating the previous high of 21C set in 2016.

The current trajectory appears to be off the beaten path, breaking previous records, said Professor Matthew England, a climatologist at the University of New South Wales.

Three years of La Nia conditions across the vast tropical Pacific have helped suppress temperatures and mitigate the effect of rising greenhouse gas emissions.

But scientists said heat is now rising on the ocean surface, pointing to a potential El Nio pattern in the tropical Pacific later this year that could increase the risk of extreme weather and further challenge sea records. global heat.

Dr Mike McPhaden, principal investigator at Noaa, said: La Nia’s recent triple dive has come to an end. This prolonged period of cold dampened global average surface temperatures despite the increase in greenhouse gases in the atmosphere.

Now that it’s over, we’re probably seeing the signal of climate change coming through loud and clear.

La Nia periods characterized by cooling in the central and eastern tropical Pacific and stronger trade winds have a cooling influence on global temperatures. During periods of El Nio, ocean temperatures in these regions are warmer than usual and global temperatures rise.

According to data from Noaa, the second warmest global average ocean temperature coincided with El Nio which ran from 2014 to 2016.

THE the data comes mainly from satellite observations but also verified with ship and buoy measurements. Data does not include polar regions.

More than 90% of the extra heat caused by the addition of greenhouse gases to the atmosphere from the burning of fossil fuels and deforestation has been absorbed by the ocean.

A study last year found that the amount of heat building up in the ocean is accelerating and penetrating deeper, providing fuel for extreme weather.

England, co-author of this study, said: What we see now [with the record sea surface temperatures] is the emergence of a warming signal that more clearly reveals the imprint of our increased interference with the climate system.

Measurements from the upper 2 km of the ocean show the rapid accumulation of heat in the upper parts of the ocean, especially since the 1980s.

Dr Kevin Trenberth, a climatologist and distinguished researcher at the US National Center for Atmospheric Research, said observations showed the heat in the tropical Pacific extending to more than 100 meters.

He said the heat would have ripple effects on the atmosphere above, creating more heat, adding energy to weather systems and causing sea heat waves.

Dr Alex Sen Gupta, an associate professor at the UNSW Center for Climate Change Research, said satellites have shown that on the surface of the ocean, temperature increases have been almost linear since the 1980s.

What is surprising is that the last three years have also been very warm, despite the fact that we have had La Nia conditions, he said. But it is now even hotter and we are getting what looks like record high temperatures.

Sen Gupta is part of an international team of scientists studying marine heat waves which are classified by his group as an area of ​​the ocean with temperatures in the 10% highest on record at this time of the year. year for at least five consecutive days.

Current observations show moderate to strong marine heat waves in several regions, including the southern Indian Ocean, the South Atlantic, off northwest Africa, around New Zealand, off northeast Australia and the western Central America.

It is unusual to see so many fairly extreme marine heat waves at the same time, said Sen Gupta.

While marine heat waves can be caused by local weather conditions, studies have shown they have increased in frequency and intensity as the oceans have warmed, a trend that is expected to worsen with human-induced global warming.

Warmer oceans provide more energy for storms, while endangering ice caps and raising global sea levels, due to the expansion of salt water as it warms .

Marine heat waves can also have devastating effects on marine wildlife and cause coral bleaching on tropical reefs. Experiments have also suggested that warming oceans could drastically alter the food web, promoting algae growth while reducing the types of species humans eat.

Professor Dietmar Dommenget, a climatologist and modeller at Monash University, said the signal of human-caused global warming was much clearer in the oceans.

Obviously, we were in a rapidly warming climate and were going to see new records all the time. Many of our forecasts predict an El Nio.

If that happens, see new records not only in the ocean but on land. This data already suggests a record and there could be more later this year.