Climate change leads to heatwaves in the sea as well as on land. We investigate the long-term effects of marine heatwaves in the Mediterranean, and ask if anything can be done to help iconic colonies of corals to survive.
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00:00 Climate Now in collaboration with Copernicus.
00:04 Hello and welcome to Climate Now.
00:16 We're here from Marseille in the south of France.
00:19 We're about to take a deep dive into the Mediterranean
00:22 to investigate the long-term effects of marine heatwaves.
00:26 It's a bit confusing because we're working on things
00:29 that we're almost certain will die soon.
00:31 Before we head out to sea, let's check the latest data
00:38 on our warming planet from the Copernicus Climate Change Service.
00:42 On a global scale, we just had the hottest January on record
00:46 with temperatures 0.7 degrees Celsius above the 1991 to 2020 average.
00:52 There was a huge contrast in temperatures across Europe.
00:55 In Scandinavia, there was a particularly cold spell in early January
00:59 with temperatures the lowest they've been for decades in some parts of Lapland.
01:04 Meanwhile in Spain, people flocked to the beach in Barcelona
01:07 as temperatures soared 8 degrees or more above average towards the end of January.
01:12 Across the planet as a whole, this map of temperature anomalies
01:15 shows how the above-average temperatures of 2023 continued into 2024.
01:21 It's particularly warm over the oceans at the moment.
01:24 Data for January indicates the sea surface temperature in non-polar regions
01:28 is already at least as high as the all-time record set in August last year.
01:33 Well, now to our story.
01:37 And this region of the Mediterranean has been hit by heatwaves for decades.
01:42 So what impact is that having and can we do anything about it?
01:46 It's time to load up the boat with diving gear and head out to sea.
01:52 These researchers are measuring the effects of marine heatwaves on a long-term basis
01:56 and they're setting off to check corals close to Marseille.
02:18 This picturesque coastline was hit by marine heatwave conditions in 1999, 2003, 2015, 2022 and 2023.
02:27 Marine biologists Tristan Estac and Justine Richaume
02:32 have witnessed how colonies of corals and gorgonians
02:35 disappeared from the first 10 or 20 metres of water.
02:38 Today, they're counting and measuring the colonies in deeper, cooler zones.
02:44 The fact is that everything that died in 2022 is still dead.
02:48 So there are still a lot of gorgon skeletons.
02:50 And when we get to 35, 40,
02:52 there's a dense population that's in good health,
02:54 as it was in previous years.
02:57 So this one hasn't been hit yet.
02:58 The video and photos the scientists take offer them a solid base
03:04 to monitor how marine heatwaves are killing off certain species in the Mediterranean.
03:08 Justine Richaume picks out three photos of the same area near Corsica
03:12 to illustrate what's happening.
03:15 Here we have three images that correspond to three different years.
03:18 So 2015, 2017 and 2023.
03:21 On the oldest image, we can see colonies of Mediterranean red corals in perfect health.
03:26 On the second image, we can see that the colonies are starting to die.
03:30 We can see necrosis and dead tissue.
03:33 This can be due to thermal anomalies.
03:36 And finally, on the last image, we can see that these colonies of red corals
03:39 have completely fallen and reflect a rather flat structure of the habitat.
03:45 And so, no more habitat available for fish.
03:48 Globally, the number of marine heatwave events has doubled since 1982
03:53 and species that can't move, like corals, are some of the worst affected.
03:57 Scientists say the main thing we can do to help them
04:00 is to prevent fishing and tourism around vulnerable areas.
04:03 Maybe by removing the human pressures,
04:05 we give them a chance to adapt.
04:07 Maybe a mutation will appear
04:09 and we'll have super colonies that will adapt to climate change
04:12 and that will then, in the most beautiful of worlds,
04:15 by reproduction, be able to regain the layers of depth that are more on the surface.
04:20 However, marine heatwaves are forecast to become more frequent and intense.
04:24 And even in the best conditions, these species grow at just a few millimetres per year.
04:29 On a human scale, we won't be able to find the landscapes that have been lost
04:33 following heatwaves of 99, 2003 and 2022.
04:38 Well, that is all we have time for,
04:42 but you can read a lot more about how our planet is changing
04:45 on euronews.com/climateland.
04:47 And I'll see you next time.
04:49 Euronews
04:54 Climate Now in collaboration with Copernicus.
04:58 (gentle music)