“Agroclimatic conditions catastrophic for ecosystems”

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[EN VIDÉO] Our agriculture will soon be affected by global warming
Some of the effects of global warming are already being felt. Others have not yet arrived. The yield of certain crops can thus decrease significantly from 2030 under the influence of rising temperatures, variations in precipitation patterns and high levels of carbon dioxide (CO2) in the atmosphere. This is the conclusion from researchers who have been working on the most effective climate and crop models at the moment. Maize yields, for example, can fall sharply. (in English) © NASA Goddard

This Monday, July 18, 2022 it was 42.6 ° C in Biscarosse (Landes), 41 ° C in Niort (Deux-Sèvres), 40.7 ° in Angers (Maine-et-Loire) and 39.3 ° C in Brest (Finistère) – it is more than 4 ° C warmer than the previous one record heat established in 1945. Unheard of. And it’s not over. That heat continues on its way east.

Such temperatures, we now know, are hard to bear. Yesterday, Spain and Portugal, which live under the same heat wave than France, reported a total of at least 344 heat-related deaths in one week. But men are not the only ones suffering from the situation. fully season culturally it also affects plants and animals. ” That corn slows its growth from 31 ° Cexplains online Serge Zaka, doctor of agro-climatology. At 40 ° C, its growth and development simply stops. The conditions we are currently experiencing are catastrophic ecosystems “.

However, it is not directly the heat that really poses a problem. “When such heat wave lasts, it is the water problem that precedes the thermal problem. » Because with the heat, evapotranspiration increases and in a context with drought marked, the water index of the plant may fall.

Heat and humidity, two parameters to take into account

That pets experiencing the same type of difficulty. To assess the risk, the researchers rely on an index that takes into account both temperature and relative humidity, the THI index – to Temperature humidity index. “It is a warning indicator”, explains Bertrand Fagoo, from Livestock Institute (Idele). Thus at a relative humidity of 30%, e.g. stress extreme will be reached from 38 ° C. At a humidity of 90% it is reached from 30 ° C. in these two situations a single THI value of 84.

But “the sensitivity is different depending on the speciesspecifies Bertrand Fagoo. Ruminants, for example, produce a lot of heat. They are much more sensitive to heat than to cold. Among them cow Dairy products are the most sensitive. When vagheat last June, “Lethal levels reached for the first time in France”reported Serge Zaka on his LinkedIn account .

Note, however, that the THI index does not take into account any control measures that farmers may implement. So much the easier when they are alerted upstream. But what are these measures? “Shade in the meadows thanks to treesand shade in the buildingstells Bertrand Fagoo. But also of ventilation, with open buildings. Without bringing in Sun . If necessary, we can even add fans. However, this is not enough. ONE veterinarianreminded him yesterday of his bill Twitter . Supporting images.

Water in the heart of the fight

You also need water. Lots of water. Because “the dairy cow doubles her need in hot weather”. So offfresh water and clean is the best way to help him keep his body at the right temperature.

The rations must also be adjusted. It is a bit technical, but during a heat wave, researchers advise to reduce the level of cellulosein cow feed. Below digestion cellulose actually produces extra heat in large quantities. It is therefore better to concentrate the ration instead energyand in protein. And better distribute it in the evening so that it stays fresh longer.

A growing risk with climate change

” With climate changethe risk will increase “, warns Bertrand Fagoo. For the time being, these measures make it possible for the most part to maintain a certain level of well-being and health for ruminants. “But the sector is still working to adapt. » Some countries that are warmer than France, e.g. Israel, already has to resort to far greater means. ” That mechanical ventilation , shower and buildings open on all four sides. » Disasters have occurred, especially in the United States. Last June, when temperatures rose sharply along with humidity. Thousands of animals perished. “In outdoor feeding grounds with animals gathered without shadetells us the expert from Idele. Fortunately, this breeding model does not exist in France ”.

Without dying, “The risks are still real for health and well-being” of our cows. Fatigue, weakened immune system, metabolic diseases are just a few examples of the genes they can be exposed to in case of high temperatures. The problem is also that the problems do not stop as soon as the temperatures drop. They extend over time. The longer a heat wave lasts, the longer the recovery time will be.

The effects on milk production can even be felt weeks after the heat wave. Because yes, the consequences for the operators also exist. As the temperature rises, milk production decreases. “Production quality is also declining”, specifies Bertrand Fagoo. Reproductive problems appear. On the one hand because duration and the intensity of the cow’s heat decreases. On the other hand because thermal stress may cause abnormal embryonic development.

So many more reasons to drastically and urgently reduce ours emissionsof greenhouse gas!

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