Les océans changent de couleur, l'eau devient plus acide et les poissons suffoquent : alors qu'une grande partie de l'Atlantique et plus de la moitié de la Méditerranée connaissent des températures de 5 degrés au dessus des normales de saison, quels sont les effets des températures records sur nos mers et océans ? Décryptage avec Marina Lévy, directrice adjointe du département sur les océans de l’Institut pour la recherche et le développement.
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NewsTranscription
00:00 It's really good, isn't it?
00:02 Yeah, but it's hot.
00:03 Really hot.
00:04 It's even hotter in the oceans.
00:06 The color of the oceans changes,
00:08 the fish drown and the marine animals migrate.
00:10 And all this is because the average ocean temperatures
00:12 are breaking records.
00:14 In a large part of the Atlantic and almost half of the Mediterranean,
00:17 we are +5°C compared to the normal season.
00:20 But what does the ocean heat up do for plants and marine animals?
00:24 We will ask Marina Lévy,
00:26 assistant to the Department of Oceans at the Institute for Research and Development.
00:30 It's catastrophic.
00:32 It's a disruption of unprecedented marine ecosystems.
00:36 The habitats of all marine species
00:39 will be both warmer and with less oxygen.
00:42 And they also find themselves more acidic
00:44 because the ocean captures CO2.
00:46 And it turns out that there are certain species,
00:48 such as moths for example,
00:50 but also very small phytoplanktons
00:52 called coccolithophores,
00:54 which have small shells
00:56 and have a lot more trouble developing in more acidic waters.
00:59 And you can imagine that if these small animals
01:01 that are at the bottom of the food chain do not develop,
01:04 it's a big fear for those who are at the top.
01:06 What also threatens the fauna and flora in the water
01:08 are the marine heatwaves.
01:09 It's a phenomenon that has the same destructive effects
01:11 as our heatwaves on Earth.
01:13 Except that since it's in the sea, we don't see them.
01:15 We saw absolutely impressive images
01:17 with beaches covered with dead fish.
01:19 And that was really due to a marine heatwave
01:22 that caused this episode of oxygen loss.
01:25 The fish have literally suffocated.
01:27 We also have more and more animals
01:29 migrating in search of new food.
01:31 Exotic fish moving to more northern latitudes
01:34 to find more suitable temperatures.
01:36 And even oceans that turn green
01:38 because the structure of the microalgae that make them up
01:40 is changing.
01:41 We don't know the consequences of all this yet,
01:43 but what we are sure of is that we have a lot to depend on the sea
01:45 to work, feed, for leisure,
01:48 or even for medical research.
01:50 To find our blue paradises, there is only one solution.
01:52 We have to drastically reduce our emissions.
01:54 Next time, we'll talk about the effects of climate change
01:56 on our land animals.