In the abyss, where sunlight is mythical, global warming invites itself. With its share of disastrous consequences that scientists had not yet been able to observe; focused on what was happening at the surface level of the oceans.
In just a decade, however, heat waves have increased by 50%, a study published in the journal reveals today Nature and led by a team of researchers from the American public agency responsible for the study of the ocean and the atmosphere (NOAA).
Heat waves. Literally. At a depth of a few tens of kilometers, they rage, upset ecosystems, rake wide and last a long time. Long time. A two-week heat wave has nothing to do with it. We are talking about several years here.
The most concrete example is that of “Blob”, in 2013, which the scientific community had then only observed on the surface. From the coasts of Alaska to Mexico, she traveled thousands of kilometers over three years. It affected, as NOAA put it, “the productivity and distribution of organisms as small as plankton and as large as whales.”
In the scientific journal, lead author and climate scientist Dillon Amayawho has made maritime heat waves his main subject of research, exclaimed: “this is the first time we’ve been able to really dive deeper and assess how these extreme events play out”.
In view of the danger of these “ocean heat waves”, he explained that the teams of the physical science laboratory of NOAA had redoubled their efforts to catch up and “understand how they form and dissipate, and predict them in advance”. Note that NOAA scientists focus mainly on coastal areas in the United States.
To be able to study the depths, the teams use what is called “reanalysis”, based on data limited to the surfaces and previously recorded. Thanks to the new tools, it is possible to understand what is happening below. That said, one of their main observations is that heat waves at depth can be completely independent of those on the surface, which contributes to their complexity and difficulty in preventing.
© NOAA
On the map above, you can see a satellite forecast heat waves estimated at the beginning of 2024 by NOAA. We clearly distinguish, depending on the colors, the areas most at risk. Close to Europe, the probability is very strong south-west of the Portuguese coast, the Canary Islands and further offshore. In the north, near Ireland, the area is also particularly affected.
Unlike the surface of the oceans, which can be observed in many different ways, the abyss is the scene of many more unknowns for us and without this research on heat waves, consequences on marine ecosystems could have occurred without us do not understand their cause.
The ocean, defender of the climate and main victim
The ocean may be less monitored, but it remains the main player in the fight against global warming, even though it plays a 90% role in absorbing the additional heat released by the increase in greenhouse gas emissions, such as remind him the United Nations on their website. Nearly half of the world’s population (3.3 billion people) today depends on fishing to meet its protein needs.
The United Nations, in the past, had already assessed that 60% of the world’s maritime areas had already experienced a heat wave and that the majority of these had taken place between 2006 and 2015.
So how problematic are heat waves and triggering what is called coral “bleaching”? At the bottom of the oceans, “every fraction of a degree counts”, as noted by the United Nations. Between 2011 and 2020, the ocean gained 0.88 degrees, the same temperature increase as the period 1850-1900, can we add reminders of the NOAA study.
Today, with 2 degrees of additional warming in the oceans, quite simply 99% of coral reefs will disappear.
