2021 will not be remembered as the hottest year on record. Not in the atmosphere at least. But in the oceans a whole different story is playing out. Researchers confirm to us today that they were, last year, hotter than ever.
In 2021, the temperatures of our atmosphere have not reached new record (fifth place in the hottest years). The European climate change monitoring service, known as Copernicus, confirmed this yesterday. On the other hand, data published today by the Chinese Academy of Sciences and the United States Agency for Ocean and Atmospheric Observation (NOAA) show that our oceans were, last year – and for the sixth year in a row – warmer than ever. At a depth of between 150 and 450 meters, the average ocean temperature reached 14.4 ° C. It was 13.8 ° C in 2000!
Bad news, because remember that the heat of the oceans is a major indicator of anthropogenic global warming. The seas, in fact, absorb a great deal of the excess heat present in our atmosphere. Over 90%.
Researchers now show that in 2021, the oceans, in their upper 2,000 meters, have absorbed at least 14 zettajoules – or 1021 joules – more than in 2020 – and even up to 227 zettajoules more than the average for the period 1981-2010. To get a better idea, know that in one year, all human activities on the planet consume one energy about … half a zettajoule!
Another consequence of anthropogenic greenhouse gas emissions
So no natural variation of type El Niño Where La Niña cannot be held primarily responsible. These variations, in fact, mainly affect the temperatures on a regional level and a relatively short period. And in addition to its magnitude, this warming can be seen everywhere in the world.
In addition, researchers tell us that the oceans have been warming significantly and continuously since the end of the 1960s. But since the late 1980s, their temperature has risen at a rate up to six times that of previous decades. And it is certain regions of the Atlantic Ocean, the Pacific Ocean and the Indian Ocean that appear to be the most affected.
Bad news for the planet
By absorbing so much heat, the ocean is in difficulty. His water is heating up. With consequences on its properties and its dynamics. On his volume, for example. Because when its temperature rises, water expands. Result, the sea level mounted. When the oceans warm, its exchanges with the atmosphere are also modified. And with them, the cycles of precipitation and finally, the frequencies and intensities of extreme weather events.
Another worrying element underlined by the researchers: with its warming, the ocean loses its capacity to absorb the carbon dioxide (CO2) of the atmosphere. He therefore leaves more in theair than previously. A sort of vicious circle. And a better understanding of this heat / carbon coupling phenomenon could therefore prove to be crucial in the near future. Even if it seems more obvious than ever that until we reach the goal of zero emissions clear, the oceans, too, will inexorably continue to warm.
Record temperature for the oceans in 2020
We are used to evaluating global warming by the increase in the temperature of our atmosphere. But researchers are reminding us today that the world’s oceans are also warming. In 2020, they hit a record high temperature.
Article by Nathalie Mayer published on 01/13/2021
In 2020, the CO rate2 in the air have increased further. Temperatures have climbed. Including those of the ocean, confirms us today a study carried out by a international team of researchers. Between the surface and a depth of 2,000 meters, never since 1955, the average temperatures of the ocean had been as high as in the course of last year.
Based on measurements present in a database global, researchers calculated that in 2020, the oceans absorbed 20 zettajoules (ZJ) – or 20×1021 joules – more than in 2019. An amount of heat sufficient to boil 1.3 billion kettles each containing 1.5 liters of water! Note, however, that while the US Agency for Ocean and Atmospheric Observation (NOAA) comes to the same conclusion of an increase in ocean temperature since 2019, its numbers are more moderate – only 1 ZJ of additional heat. absorbed. All of this confirms a basic trend.
Don’t overlook the importance of the ocean
Fortunately, the ocean is vast. He does not boil. By absorbing a large amount – the researchers speak of 90% – of the excess heat, it cushions the global warming. But at what cost ? That of modifications of salinity and increased stratification. That of a slow release of this accumulated heat also, enough to maintain the effects in the long term. Even after our CO emissions have stopped2.
More immediately, warmer oceans promote more intense rains, and hurricanes and more powerful typhoons. With the floods and the material and human damage that can accompany them. Hence the importance of not forgetting to consider the ocean when policies to fight against global warming are put in place.
The ocean is experiencing unprecedented temperature increases
The report of the Intergovernmental Panel on Developments in weather (IPCC) dedicated to the question asserts that the world ocean has been warming relentlessly since 1970. And today, data from the Copernicus program clarify the question: the ocean is experiencing an unprecedented increase in temperature.
Article by Nathalie Mayer published on 10/11/2020
Each year, the Copernicus program – a European Union program for the observation and monitoring of Earth – publish a state of the oceans report of the world. It is based on satellite data, field measurements and expert analyzes. The one that has just been published reports an unprecedented increase in sea temperatures.
Between 1993 and 2018, the global sea surface temperature – one of the important measurements, along with the heat content of the ocean – increased by 0.014 ° C per year. The past four years appear to be the hottest on record.
Signs of major tensions on the oceans
What researchers call the heat content of the ocean refers to the heat absorbed by the ocean. Know the amount ofthermal energy stored in the ocean is essential for understanding the state, variability and changes of the Earth’s climate system. In the last quarter of this decade, global ocean heat gain increased in the upper 700 meters of the ocean. Heat has been trapped in deeper ocean layers, reaching over 2,000 meters.
Recall that the increase in the heat content of the oceans contributes 30 to 40% of theglobal mean sea level rise, due to the dilation thermal sea water. “More than ever, a complete and systematic monitoring of the oceans is necessary”, remark Karina von Schuckmann and Pierre-Yves Le Traon, researchers, in a press release Taylor and Francis Group (UK). Especially since the report underlines other major tensions on the seas and oceans of the world due to the climate change, especially acidification – caused byabsorption carbon dioxide (CO2) of the atmosphere – the loss of oxygen and the retreat of sea ice. ecosystems sailors than the human societies that make a living from them.
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