[LUM#2] Heat Wave in the Mediterranean

[LUM Magazine] - Published on April 5, 2016 in Science and Society

For climate experts, the time for speculation is over: climate change is here. And its impact on the regional landscape is already clearly visible.

1.5 degrees. That is the temperature increase that the COP21 agreement aims to keep below. The goal: to limit the damage. Because it’s clear that we can’t ask for more. And for good reason:“The consequences of global warming are no longer a thing of the future—they’re right here, before our eyes,” confirms Eric Servat. This is particularly true in the region:“The Mediterranean basin is a hotspot for climate change,” explains the director of the Research Environmental Research Observatory.

“The number of rainy days per year is decreasing; in 2015, there was a long period of near-total drought between early June and mid-August,” notes Eric Servat. A scorching summer, typical of the Mediterranean. And often followed by a torrential fall: “Inthe fall of 2014, for example, there were no fewer than nine major weather events in Languedoc-Roussillon,” the hydrologist notes. To sum up: summers that are getting hotter and drier, followed by torrential downpours starting in September. A typically Mediterranean climate, it seems. The problem is that this trend is becoming increasingly pronounced. And according to researchers’ predictions, extreme weather events will become more and more frequent.

As a result of these climate upheavals, ecosystems are changing at the speed of a raging torrent. And the species that inhabit them are forced to adapt, or risk extinction. In Montpellier, researchers are assessing the impact of these changes on flora and fauna. And they are sketching out the new contours of a biodiversity map that is currently being redrawn.

Migratory Trees

Although firmly rooted in the ground, trees are nevertheless beginning to migrate like birds.“Mediterranean species will move northward and climb to higher elevations,” predicts Isabelle Chuine of the Center for Functional and Evolutionary Ecology, who heads the Seasonal Observatory. Some species, such as the holm oak, have already begun this slow migration.“It’s estimated that it will find a favorable climate by 2050… but far to the north of the Mediterranean,” explains the ecologist. And for those that don’t move, a new “wardrobe” is needed to cope with the heat. “The oaks in the Puéchabon Forest, 30 km from Montpellier, have reduced their number of leaves in recent years,” says Isabelle Chuine. “This is a way for them to transpire less and require smaller amounts of water.”

Vines in Danger

It is the most beautiful wild vineyard in France: about a hundred vines clinging to the foothills of Pic Saint-Loup. This heritage is now in danger:“For the past two years, some vines have been struggling to grow; they’re suffering from a lack of water, and their foliage is being scorched by the sun,” laments Jean-Frédéric Terral of the Institute of Evolutionary Sciences in Montpellier. With these few vines, the ancestor of all the world’s grape varieties is at risk of disappearing. And its domesticated descendants aren’t faring any better.“Some grape varieties planted in the region are reaching the limits of their climatic requirements,” the specialist points out. It’s a tough time for Merlot in particular, an early-ripening variety that doesn’t handle heat waves well. “If it gets too hot, its entire growth cycle is affected, from flowering to fruit set. Furthermore, harvests are occurring earlier and earlier, the grapes are of lower quality, and the alcohol content of the wines is increasing—which is not the desired outcome,” explains Jean-Frédéric Terral. As a result , winegrowers will likely have to uproot their Merlot vines and replace them with sun-loving varieties.

When a baby chick hatches too early

Great Tits and Mediterranean Blue Tits are traditionally very busy when spring arrives. The family has grown, and they must feed their little chicks, who, as soon as the shell cracks open, begin to chirp away as loudly as they can. On the menu for these first meals is a delicacy: caterpillars that swarm as young oak leaves sprout. But with global warming, these leaves are appearing earlier and earlier in the year, and the young chickadees risk missing out on the feast. “For now, the chickadees have found a solution: over the past half-century, they’ve moved up their nesting date by two weeks to stay in sync with their food supply, ”explains Anne Charmantier of the Center for Functional and Evolutionary Ecology. “But if global warming becomes too severe, they won’t be able to move up their nesting date enough,” she warns. And their chicks could very well end up high and dry…

Fish Facing Deportation

And things are heating up in the water, too.“The Gulf of Lion is one of the coldest regions in the Mediterranean, so it serves as a refuge for fish species that don’t tolerate heat well, such as the sprat,” explains Pierre-Alexandre Gagnaire of the Institute of Evolutionary Sciences in Montpellier. The problem is that these waters are getting less and less cold.“In the Atlantic, fish can migrate northward to stay cool, but in the Mediterranean they quickly find themselves trapped,”the expert notes. Mediterranean sprat populations are therefore at risk of melting away like snow in the sun.“Conversely, other species are making an appearance, such as the flutefish and the rabbitfish, which have made the journey from the Red Sea through the Suez Canal.” And upon arrival, they find the warm water they love.

Keywords: Biodiversity, Climate, LUM#2, LUM Magazine, Global Warming