Despite the unprecedented crash in greenhouse gas emissions in 2020 due to the pandemic lockdowns, the oceans are still alarmingly warming up. Never since it began being recorded have the waters been as warm as in 2020. According to a study conducted by an international team of scientists and published on Wednesday January 13th by the journal Advances in Atmospheric Sciences, the five warmest years for the oceans have followed each other back to back since 2015.
An essential regulatory organ for Earth
Planetary waters play a key role in balancing a tolerable temperature on Earth: according to the research, over 90% of the excess radiative heat captured by CO2 is absorbed by the oceans. They are essentially a heatsink for the world's surface. This rise in the average temperature not only causes a rise in sea levels thanks to melting glaciers, but also represents an aggravating factor in the formation of climatic catastrophes.
Storms, hurricanes and cyclones are consequently more numerous and more violent: 29 storms were recorded in the Atlantic last year, another record broken. The multiplication of these storms 'worsens the risk of flooding and significant damage,' write the twenty authors from fourteen international institutes.
The data compiled by the scientists focused on a depth of some 2,000 meters. Since 1986, the rate of warming of this layer of the oceans has been eight times that of the period 1960-1985. The rise in sea level could reach one meter by the end of the century, according to the researchers, directly threatening 150 million people living on coasts around the world.
Warmer water is also less conducive to absorbing carbon dioxide and therefore less likely to help in limiting the effects of global warming. As of today, 30% of CO2 is captured by the oceans. According to the study, the Southern Ocean 'has absorbed most of the human-made heat over the past century (...) in parallel with significant ocean warming since 1958.'
The world's nations attempt to shore up the damage
The climate emergency has prompted many governments to embark on the path of carbon neutrality in the decades to come. Flattening the curve of ocean temperature rise will represent a much more difficult challenge, according to scientists.
The excess heat already present in the ocean and the heat likely to penetrate into the ocean over the next few years will continue to affect climatic conditions, sea level and ocean biodiversity for a quite some time, even under zero carbon emission conditions.
Even if we apply the brakes, it's going to take a while for the speeding lorry to come to a stop.
The average temperature on Earth in 2020 was 1.2°C higher than in the pre-industrial period according to the World Meteorological Organization - a figure extremely close to the threshold of 1.5 ° C set by the Paris Agreement.
In the UK, 2020 was the hottest year recorded since the start of measurements, according to the Met office. In fact, none of our coldest years have happened since 1963!