Sea level rise, melting of glaciers, intense weather events, deterioration of the population's health: the effects of climate change are already being felt. Apart from any more or less pessimistic attempts to project in the future, Science and Future looked at these effects already visible today, in a summary not exhaustive but drawing nevertheless a broad panorama.
“Over the last 50 years, human activities, particularly the use of fossil fuels, have released sufficient amounts of carbon dioxide and other greenhouse gases to retain more heat in the lower layers of the atmosphere. and affect the global climateThe World Health Organization (WHO) is setting the scene, recalling that in the last 130 years, the temperature has risen by about 0.85 ° C worldwide, and that in the past 25 years, the pace has accelerated to reach a warming of over 0.18 ° C per decade.
Nearly two-thirds of the global effects of changes in temperature in the atmosphere and at the ocean surface between 1971 and 2010 have been attributed to anthropogenic (man-made) climate change, according to a study published in the New England Journal of Medicine in January 2019. Result, in 2019 already we can note that the level of the seas rises, the glaciers melt and the heat waves multiply. On the health side, beyond the direct effects of rising temperatures, nutrition and allergies are affected.
1) Increasingly hot temperatures
“It is clear that frequency and intensity“hot episodes”has grown over the last thirty years“, explains Météo France, which has data since 1947. Involved: the cooling capacity of aerosols in the upper atmosphere where they block the solar radiation is weakened with the increasing content of greenhouse gases.
As a result, landslides are multiplying in the Alps, where a lake has even been discovered at 3,000 meters altitude. According to the experts of World Weather Attribution, the probability of a heatwave week such as in France at the beginning of summer 2019 is ten times higher than it was at the beginning of the 20e century, with an average temperature higher than 4 ° C compared to a century ago. “Every heat wave that occurs in Europe today is made more likely and more intense by man-made climate change“, add these experts.
But the phenomenon is of course not limited to Europe. In early June 2019, in India, temperatures rose to 50 ° C for several days in a row. The monsoon, a welcome source of refreshment, was a week late. In Canada, a government report concluded that the country is warming twice as fast as the rest of the world, with +1.7 ° C since 1948, compared with + 0.8 ° C worldwide. In Australia, the fourth consecutive monthly heat record was recorded in March 2019. And warming is felt to the far north. Don July 14, 2019, mercury reached 21 ° C in Alert, less than 900 km from the North Pole, establishing a “absolute record” of heat for this station.
2) The oceans are warming up and rising
“Ocean warming is a very important indicator of climate change, and we have evidence that this warming is going faster than we thought“in January 2019, the scientist Zeke Hausfather, from the University of California at Berkeley, explained. Because the oceans absorb excess heat from the atmosphere created by greenhouse gas emissions. While their temperature has already increased by 1 ° C, heat waves affect an ocean surface three times greater since the pre-industrial era.
With this sea warming, the plankton go north to find a more favorable temperature, at the risk of unbalancing the fauna feeding on it. DIn the Arctic, seals and whales are already forced to change their eating habits, either by hunting new species pushed north by the heat, or by hunting the usual species further north. For their part, corals stressed by the warming of the water expel the micro-algae with which they live in symbiosis, and whiten. Bleaching makes them vulnerable and can lead to their death. In recent years, 30% of launderings have been classified as “Severe” extending over tens of thousands of kilometers, especially in Asia, Australia and the Near East. According to scientists, the risk for such a phenomenon has increased by 4% per year since 1980.
Direct consequence of warming: rising water. “During the 20th century, the level of seas rose by about 20 cm“, says Météo France, against 5 cm per century over the last two to three millennia. A climb that could reach 2 meters in 2100, with disastrous consequences.
3) The ice melts
Two reasons make the ocean level rise. First, the water expands when the temperature rises. The second factor is melting ice, a large amount of which is found in mountain glaciers, Antarctica and Greenland, and is intensifying.
The consequences are many. In Alaska in 2015, a massive landslide caused by the retreat of the Tyndall glacier generated a tsunami of nearly 200 meters. “The glaciers, retreating, change their environment dramatically”explained Dan Shugar from Washington University Tacoma. In Siberia, buildings are cracking because of the melting of permafrost that support them, a mineral layer cemented by ice and which remains stable only if the water is frozen. Elsewhere in Siberia, in October 2018, uA ship of the French Navy crossed for the first time the Northeast Passage, this mythical sea route along the Arctic coast, without the help of an icebreaker.
SOLUTIONS. “We affirm that we have all the technical and economic means to achieve this goal” not to exceed + 1.5 ° C, In 2018 Valérie Masson-Delmotte, paleoclimatologist and vice-chair of the IPCC working group on the physical study of the climate, was in charge. To learn more, read our article: Stay below 1.5 ° C: painful efforts for huge profits
4) Forests burn
Far from the glaciers, global warming also plays with fire. “By drying up vegetation, climate change is causing (since the 1960s) an increase in the weather hazard of forest fires“, explains Météo France. “Climate change, in addition to bringing drier and warmer air, creates more flammable ecosystems by increasing the rate of evaporation and the frequency of droughts“, explained Christopher Williams of Clark University in Massachusetts. With rising mercury and less precipitation, the roots of shrubs and trees will pump water deeper into the soil. As a result, the wetland that could have slowed down a forest fire is no longer there. And forest fires, in addition to being more frequent, are more intense.
In the temperate zones of the northern hemisphere, the fire season was traditionally limited to July-August and now extends from June to October in the Mediterranean basin. In California, experts believe that wildfires can now erupt throughout the year. Southern France and Portugal have experienced several drought episodes in the past 20 years, as they did before only once a century. In 2018, Greece and California were particularly ravaged by fires.
And it's a real vicious circle. Forests are indeed gigantic carbon sinks, of which they store around 45% worldwide. When they burn, some of the carbon is released into the atmosphere, contributing to global warming.
5) More floods and droughts, and a tendency for storms and cyclones
“Extreme” weather events bring together heat waves and fires, as well as cyclones, storms, floods, tsunamis and floods. At the global level, these events have more than doubled between 1980 and 2016, according to a 2018 report from Council of Academies of European Sciences (EASAC). In particular, extreme hydrological hazards (floods, floods) have quadrupled, and droughts doubled.
But at the scientific level, storms, tropical cyclones and extratropical cyclones (as characterized by climate specialists) are more complex cases. “With a decline of only 40 years, it is impossible to distinguish the impact of climate change from the natural variability of the phenomenon.“, says Météo France about tropical cyclones.If it is still difficult to separate things, experts expect less cyclones, but with more power for the strongest of them, who will draw energy from the humid atmosphere over warmed oceans.
“Storms are not one-dimensionalAnthony Del Genio, a climatologist at NASA's Goddard Institute for Space Studies, told the Earth's Observatory mission in 2013. The humidity of the atmosphere, the differences in temperature between the oceans, but also between the masses of air, are essential parameters for their formation.
6) Health: more allergies, respiratory problems, anxiety
The effects of global warming on health are numerous and can be direct, such as dehydration during the heat wave (70,000 additional deaths were recorded during the heat wave of summer 2003 in Europe), or the psychological effects of events related to climate. For example, exposure to floods and other extreme events increases the risk of depression and anxiety. And just anticipating these disasters can affect mental health. It's this “chronic fear of a condemned environment“that the American Psychiatric Association describes as eco-anxiety.
More indirectly, deleterious effects on health can result from the consequences of climatic events. Thus, the pollution caused by the Californian fire of 2018 forced the closure of schools and the wearing of masks for many inhabitants, in order to protect their airways from particles floating in the air. Wildfires such as this one “can multiply daily air pollution levels by ten“, explains the article of the New England Journal of Medicine from January 2019.
Some diseases are favored by increasing temperatures. Warming has the consequence of increasing the amounts of pollen … and therefore allergies. In France, the number of allergies related to pollen has tripled in 20 years, affecting nearly 20% of adolescents and more than 30% of adults, warned Inserm in 2015. Warming also favors vector diseases, it is ie transmitted by a living agent such as the mosquito, very sensitive to weather conditions. Today, malaria, transmitted by mosquitoes, already kills 400,000 people a year.
On the nutrition side, New England Journal of Medicine note “Increasing levels of carbon dioxide have adverse effects on the nutritional quality of major cereal crops, such as rice and wheat, including lowering protein levels, a range of micronutrients and B vitamins“.
7) The animals go out, the plants suffer and adapt
Because of human activity, one million animal and plant species are now threatened with extinction. If climate change is not the only cause, it adds to the disastrous consequences of land use (agriculture, deforestation), direct exploitation of resources (fishing, hunting), pollution and invasive species.
The increase in temperatures is also responsible for new and disturbing behaviors in animals. Hungry polar bears, affected by the melting ice, make incursions into Russian cities. In Australia, sharks become right handed, lateralizing their movements to save energy faster spent in warmer water.
The flora suffers just as much, with a evolution of vegetation never seen over such a short period of time: between 2009 and 2019, wild flora has already changed under the effect of climate change, “all over France, in all environments“. “Species that prefer high temperatures settle (in new territories, ed) or increase in abundance“explained Gabrielle Martin of the National Museum of Natural History. The sites where the temperature has increased the most are those where the vegetation has changed the most. In French forests, the finding is similar. Top branches of oaks that dry up, Scots pine trees that die of thirst, beeches that are struggling to withstand high temperatures: for foresters, the signs of global warming are already there.
Good news for the English, however: thanks to global warming, they hope to produce sparkling wines that can compete with champagne.