The oceans are currently reaching record temperatures – and could soon “pay us back” for that.

The oceans are sweating – and at an unprecedented rate. A reversal is not in sight: researchers strongly believe that a new El Niño event is imminent as early as this year. It would warm the world – and especially the oceans – even more than it already does. How is it all arranged? An overview.

The global sea surface has been setting a new temperature record since mid-March. She has never warmed up so strong and so quickly.

Data collected by the US National Oceanic and Atmospheric Administration (NOAA), known as the OISST (Optimum Interpolation Sea Surface Temperature) series, collected by satellites and buoys, shows: Ocean temperatures through May 1 were higher than any year before for 49 consecutive days.

The temperature records of all oceans follow a year with a low ice record at both the North and South Poles. Overall, temperatures are at an all-time high, but they are also reflected in widespread regional ocean heat waves. In March, for example, sea temperatures off the east coast of North America were a whopping 13.8°C above the 1981-2011 average. The average of these 30 years is used as a basis for calculating current and future heat waves.

Such a heat wave with the highest rating of “extreme” is currently emerging in the Atlantic Ocean off the coast of Northwest Africa and Portugal. (By the way, here’s where you can interactively and quickly track ocean temperatures and heat waves.)

On average, the temperatures were between 0.1 and 0.2 degrees above the previously measured maxima. That may not sound like much, but the opposite is the case. 71 percent of the Earth’s surface is covered by oceans. If you now consider how much energy is needed to bring one liter of water to the boil, then 0.2 degrees is no small matter for more than 1.3 billion cubic kilometers of liquid.

You don’t know exactly yet. The fact is: this is a special development. Ben Webber, a lecturer in climate science at the University of East Anglia, told Britain’s Guardian: “That temperatures are so high above average, and that they are taking so long, is an anomaly.” What you see here is very special, says the teacher. And further: “We are moving in an unprecedented direction and could enter uncharted territory.”

In short: it is an anomaly that the researchers cannot yet explain. Coming back to the question of why, one thing should be kept in mind: the world is on the verge of another El Niño event this year. It is a cyclical weather system in the Pacific that occurs erratically but about every two to seven years and causes global warming.

However: the approaching El Niño has yet to develop. The final La Niña event is considered to be over soon. It was three long years in a row. This is extremely rare: it has only happened twice since registration began.

The fact that Pacific waters are currently warming unusually for South America is a sign that La Niña is about to be replaced by the next El Niño phenomenon.

However, the most recent temperature measurements cannot (only) be explained by El Niño, because the phenomenon is still considered much too weak for that. This also happens at a time of year when sea temperatures typically drop from their annual highs in March and April. Although this has already been observed for a good week with a considerable delay, the difference with previous years remains considerable.

However, as the British BBC writes, there is another factor that may have influenced the increase in heat in the oceans. Paradoxically, it reduces pollution from shipping: in 2020, the International Maritime Organization issued a regulation to reduce the sulfur content of fuel burned by ships. According to the BBC, this took effect quickly and reduced the amount of aerosol particles released into the atmosphere. But aerosols that pollute the air also help reflect heat back into the atmosphere — so removing them may have released more heat into the water.

The sighting in recent weeks has caused a stir in science. Experts and climatologists are currently exchanging information on social media and with each other. Although there is speculation about the reasons, the consequences of this are still much unclear. So unclear that the BBC writes in its report: “Several scientists approached for this paper declined to comment on the effects.” A few said only that he was “extremely worried and completely stressed”.

But one thing seems clear: if there is a pronounced El Niño event by the end of the year, it could be fatal: “In this case, we will probably have an additional global warming of 0.2 to 0.25 degrees ” said Dr. Josef Ludescher of the Potsdam Institute for Climate Research told the British BBC.

“The extra heat from an El Niño event would push some parts of our planet above 1.5 degrees of warming for the first time,” explains oceanographer Moninya Roughan for Australian newspaper The Conversation. Roughan believes what we are seeing is the weakening of La Niña. This has brought with it rather cooler conditions that mask the extra heat in our planet’s systems. This heat would now spread.

Another aspect discussed in science concerns the oceans as energy stores. A recently published study points to a worrying development: In the past 15 years, the Earth has accumulated almost as much heat as it did in the previous 45 years, with most of the additional energy being stored or absorbed by the oceans.

“Earth’s climate system has gone out of energy balance,” the researchers write. Some now fear that such an abnormally large deviation from previous temperatures as now being observed could indicate that our oceans have reached the limits of their heat capacity.

That would be particularly bad news, because nearly 90 percent of the excess energy pumped into our system by humans is absorbed by the oceans. This has allowed the water bodies to absorb much of the effects of global warming. If they could not do this to the same extent in the future, there would be significantly more excess energy on land.

However, we are not there yet. Professor Mike Meredith of the UK’s Arctic Research Program says it’s too early to say. “The speed [des Temperaturanstiegs] is stronger than climate models predict,” the scientist told The Guardian. The reason for the concern is that “if this continues, it would be way ahead of the assumed climate curve for the ocean. But we don’t know yet if that will be the case.”

Karina von Schuckmann, co-author of the above study, also tells the BBC there is still some hope in this scenario; temperatures may drop again after the El Niño subsides. “We still have an opportunity to act. And we must use that to mitigate the consequences.”

It almost goes without saying that the effects of ocean warming are enormous. This includes: