WASHINGTON.- At this time last year, Scientists found in disbelief that ocean heat had skyrocketed to record levels and they wondered what could have triggered it: Such a drastic jump in the surface temperature of the seas has never been seen.
Among the possible causes, scientists explored their possible link with the El Niño phenomenon, a weather pattern that typically warms Pacific waters, as well as the potential warming influence of reduced pollution from cargo ships and even a large volcanic eruption. But Nothing explained why this flow of hot water continued for months and spread heat waves over the surface of all the oceans..
Now, That unprecedented wave of ocean heat enters its second yearand scientists warn that may mean a drastic change in Earth’s systems that cannot be reversed on a human time scale.
And they come to that conclusion because what they are seeing in the oceans “does not close”says Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies.
“It could imply that the warming of the planet is fundamentally altering the systems that govern the behavior of the climate, and much sooner than anticipated by scientists”Schmidt wrote in a column in the magazine Nature.
The temperature “broke all records”
Ocean warming has spread far beyond portions of the Peaceful affected by El Niño.
In much of the basin AtlanticFor example, the water surface temperature is 1°C or 2°C above the comparison base 1971-2000. And in some waters as far apart as South Africa, Japan and the Netherlands, that anomaly is 3°Caccording to satellite data from the United States National Oceanic and Atmospheric Administration.
The ocean heat wave also coincides with atmospheric temperatures never before observed. Last year, the global average air temperature was the highest humanity has ever known, perhaps bringing the planet to its knees. heat peak in more than 100,000 years. Now climatologists predict that 2024 could be even hotter.
But such dramatic warming in all of Earth’s oceans is even more alarminggiven that It takes much more energy to heat water than to heat air.said Celeste Saulo, secretary general of the World Meteorological Organization (WMO).
“The time scale of the oceans is slower than that of the atmosphere”said Saul. “When a trend is established in the oceans, I would say that It is almost irreversible on a time scale of centuries or millennia”.
In its annual report on the state of the climate, the organization notes that last year the climate indicators “They gave a new and ominous meaning to the phrase ‘breaking all records’”, and adds that throughout 2023 the heat wave spread to more than 90% of the ocean surface.
The most anomalous temperatures were recorded in the eastern North Atlantic, the Gulf of Mexico and the Caribbean, the North Pacific and vast expanses of the Southern Ocean, notes the WMO. Since April 2023, global average sea surface temperatures reach a new record every month “and by a particularly wide margin”warns the organization.
Deep impact… and unpredictable
The warming of the world’s oceans has already devastating effects on coral reefs. In March, a hitherto largely virgin strip of the Australia’s Great Barrier Reef hit by deadly heat levelsand the bleaching and death of corals seen last year in Florida waters was repeated.
Even this Wednesday it was reported that the reef experienced his worst case of bleaching ever recordedreported the authorities in charge. “The cumulative impacts experienced this summer have been higher than in previous summers,” the Australian Marine Park Authority said in a statement.
Qualified as the largest living structure in the worldthe Great Barrier Reef is 2,300 kilometers long and is home to enormous biodiversity, including more than 600 types of coral and 1625 species of fish. However, aerial assessments by scientific teams show that about 730 of the barrier’s more than 1,000 reefs have lost color.
Bleaching occurs when The coral, to survive in high temperatures, expels a microscopic algae call zooxanthellae. If high temperatures persist, the coral loses color and dies. This is the fifth mass bleaching of the reef in the last eight years.
Other effects will take longer to manifest. There is concern that warming water and melting ice are leading to collapse of a key Atlantic Ocean current. It is unknown what the tipping point would be, but it would have a massive impact on underwater ecosystems and climate patterns.
It is also likely that there will be a domino effect on marine life.
In the Gulf of Maine, where water warming is much faster than in the world’s oceans in general, researchers have already detected the problems faced by some important species, such as cod and herringto find cold waters within its normal geographic distribution area.
There are many fish that now grow faster than normal during the first weeks of life, but then stagnate and do not finish developing, a sign that they are not getting enough nutrients or that the heat is stressing their vital functionssaid Katherine Mills, a scientist at the Gulf of Maine Research Institute.
Since the temperatures observed during the past year are so extreme compared to the past, It is increasingly difficult to predict with any degree of certainty what the consequences will be.Mills noted: Conditions are changing so rapidly that existing data on ecosystems become obsolete almost immediately.
“Predictive models have always taken ocean temperature variability into account, but now The range of that variability is something never seen before.”Mills indicated. “I think he is a real wake up call”he added.
And there are no signs of cooling…
Scientists don’t know if or when extreme ocean warming will slow. So far, none of the theories that have been proposed to explain what drives this phenomenon manage to answer all the questions.
It is likely that Part of the current ocean warming is related to a decrease in air pollution caused by cargo ships: The fewer emissions, the more sunlight that reaches the water surface. And the eruption of the underwater Hunga Tonga-Hunga Ha’apai volcano, near the island nation of Tonga, in 2022, released into the atmosphere large amounts of water vapor, a greenhouse gas that warms the planet. But none of these factors are enough to explain the drastic increase in ocean heat.
Ocean temperatures began to rise uncontrollably around April of last year, at the end of a spell of three consecutive years under global effects of the La Niña climate pattern, the opposite side of El Niño and known for curbing global warming.
According to Boyin Huang, an oceanographer at the National Oceanic and Atmospheric Administration specifically focused on ocean temperature analysis, Much of this jump in ocean heat could be explained by the fading of La Niña and the transition to a historically strong El Niño season.known to increase the temperature of the planet.
Therefore, ocean temperatures are likely to moderate later this year, and La Niña weather conditions are forecast to return.
But it remains to be seen whether the return of La Niña will be enough to significantly counteract warming or the power of greenhouse gases. If after winter ocean temperatures continued to break recordspart of that mystery could be cleared up, says Huang.
If record heat persisted even when La Niña returned, Schmidt wrote in his report for Nature, “the world will enter unexplored territory”with a uncertainty about the future of the climate that not even scientists could dispel.
Scott Dance
The Washington Post
Translation by Jaime Arrambide