The global ocean surface temperature reached an all-time high in July. Tarmo Soomere, president of the Estonian Academy of Sciences, says that oceanic heat waves no longer only threaten delicate underwater ecosystems, but have direct impact on the life and well being of people.
Copernicus, the climate change service of the European Union, reported that the temperature at the end of July was 1.5 degrees Celsius above the average for the period between 1850 and 1900.
The highest temperature recorded in July previously was 0.33 degrees Celsius cooler. Moreover, July's average global sea surface temperature was 0.51 degrees Celsius above the 1991-2020 average.
"It is not news that the upper strata of the ocean have warmed. In fact, this is really good news. It means that a significant portion of the increased heat of the Earth's system is actually stored in the ocean," Soomere told ERR.
In other words, record water temperatures make the planet's longer-term warming apparent and visible. In turn, a tenth of a degree higher average water temperature will result in several degrees Celsius higher atmospheric temperatures in the hottest regions. Scientists reported that for every degree Celsius that the Earth's atmosphere heats, the amount of water vapor that absorbs heat but keeps it from escaping into space can increases by around 7 percent, causing the greenhouse effect to worsen.
According to Soomere, professor of coastal engineering at Tallinn University of Technology (TalTech) and a leading research scientist at the department of cybernetics, the effects of climate change are also clearly evident in Estonia. "What we should recognize, especially after yesterday's thunderstorm, which wasn't even so bad, is that Estonia is no longer a paradise, where the effects of climate change are merely pleasant: we have reached a point where climate change is beginning to hit people hard. [...] The fact that heat waves are going to take people's lives or that hail is going to destroy our cars — we're just going to have to get used to this," he said.
We will have to learn to deal with not only weather fluctuations, but also other phenomena that have a direct impact on our health or property. Due to the added heat energy, tropical air masses are generating greater waves in the north, while arctic air masses are generating them in the south. "So what we need to adapt to is already here: it is the changing pattern of the seasons, where we have a sunny May-June in the spring but a gloomy, windy and parched summer. We must adjust to the idea that temperatures will often reach 30 degrees Celsius for weeks at a time during the summer, and although a week of heavy rain was once the norm, we must now plan for two or three weeks instead. In general, weather patterns become more long lasting," Soomere said.
Problems for marine life
While humans can adapt to the new reality, marine life has a slim chance of surviving, Soomere went on to say. The so-called red tide, for example, is currently spreading south along the South American shoreline. "It's unusually warm water that flows south along the coast, where it's (normally) chilly, and devours marine life like a dragon. When you think that every other breath of oxygen we take comes from the sea, it's no longer innocuous," the marine scientist said.
If current trends continue, marine ecosystems will be depleted soon. "The most vulnerable species and species groups are those that are newly established or more fragile," Soomere explained, adding that a 15 percent reduction in Antarctic ice thickness would be a severe blow to marine life as well. The freezing of the ocean's surface causes heavier salt to descend even deeper and the oxygen dissolved in it, on the other hand, is critical for the oxygen-consuming animals that live there.
Another phenomena is linked to oceanic circulation. The north-south heat pump of the Atlantic Ocean contributes to Estonia's relatively warm temperature for its latitude. Warm tropical water moves towards Greenland in the surface layer, while emerging cyclones bring it into northern Europe.
"Many people think that this heat pump is the foundation of all life in the Atlantic Ocean. If it halts, we won't have an ice age — we will have a climate similar to Anchorage, Alaska's southernmost city. That's not a climate we would enjoy to live in," Soomere continued. In a paper published six years ago the researchers concluded that the north-south Atlantic heat pump is in its driest state for at least the last 1600 years, he added.
Danish scientists recently reported that some processes suggest that the heat pump could completely destabilize already this century. "It's not going away anytime soon. [...] The ocean circulation will continue as long as the winds blow over the water's surface; however, if that circulation is reduced significantly, our grandchildren may encounter a little cooler, angrier and greyer environment here," Soomere said.
Copernicus monthly summary
For the month as a whole, global average sea surface temperatures were 0.51 degree Celsius above the 1991-2020 average. The North Atlantic was 1.05 degree Celsius above average, as the temperatures in the northeastern part of the basin remained above average, and unusually high temperatures developed in the northwestern Atlantic, according to the Copernicus climate service.
Marine heatwaves (MHWs) — prolonged extreme oceanic warm water events — have developed south of Greenland and in the Labrador Sea, in the Caribbean basin, and across the Mediterranean Sea.
The area of Antarctica's sea ice in July was 15 percent less than the long-term normal; it has not been this low since the beginning of regular satellite measurements. The area of Arctic sea ice was also below average, but not by much.
Surface air global average temperature for July 2023 was highest on record for any month. Heatwaves were recorded in multiple regions of the Northern Hemisphere, including southern Europe. Also, well-above average temperatures occurred over several South American countries and around much of Antarctica.
Editor: Jaan-Juhan Oidermaa, Kristina Kersa