The heat wave affecting Europe in October seems to be a new manifestation of this: global warming is already affecting the planet. But how can its consequences on human health be concretely measured? This is the task to which a hundred scientists have set themselves, publishing their annual report on Tuesday 25 October. (in English) in the British magazine The Lancet (PDF). “Health [est] at the mercy of fossil fuels”they warn.
“We are seeing the severe health impacts of climate change around the world, while the continued global reliance on fossil fuels compounds these adverse effects,” declared to World (article for subscribers) Marina Romanello, executive director of the project at University College London, who supervised the work. Here are the main lessons.
Populations much more exposed than before to heat waves
Scientists have developed 43 indicators in collaboration with 51 institutions, including the World Health Organization (WHO). They thus scrutinize data on health, the economy, adaptation policies and the objectives of States to reduce their CO2 emissions.
The most obvious consequence of the climate crisis, rising temperatures, is affecting more and more people on the planet, especially those most at risk. Thus, over the period 2012-2021, children under the age of one had to face an average of 4.4 more days of heat wave each year compared to the period 1986-2005. The figure is an additional 3.2 days for people over 65.
High temperatures aggravate certain diseases
High temperatures can cause heatstroke, but they also aggravate cardiovascular and respiratory diseases. They also cause deterioration in sleep and mental health.
In addition, they increase the risk of infectious diseases. Thus, the duration of malaria transmissibility increased by 31.3% in the high altitude areas of North and South America between 2012 and 2021 compared to the period 1951-1960.
Europe is not spared either. It has an increasingly favorable climate for mosquito-borne diseases such as dengue fever. Globally, the risk of dengue fever transmission thus increased by 12% over the period.
Hot weather drives up mortality
The researchers are able to accurately assess the increase in mortality linked to these heat waves. The number of deaths increased by 68% over the period 2017-2021 compared to 2000-2004.
“The climate crisis is killing us. It is harming not only the health of our planet, but that of all its inhabitants…as addiction to fossil fuels spins out of control”, responded the UN Secretary General, quoted by AFP. Antonio Guterres calls for investments in renewable energy and climate resilience. A year ago, the WHO estimated that between 2030 and 2050, nearly 250,000 additional deaths per year would be attributable to climate change.
Food insecurity is aggravated by drought
By disrupting the weather, global warming is increasingly weakening food security. In 2020, 98 million more people suffer from food insecurity compared to the period 1981-2010.
Scientists have managed to assess the consequences of rising temperatures on crop cycles, which are becoming shorter and shorter. In a hundred countries, scientists have calculated an average of 9.3 days less growth for corn, 1.7 days for rice, and 6 days for wheat.
The extreme drought affected 29% more land areas over the period 2012-2021 compared to 1951-1960. “Drought poses risks to food and access to water, threatens sanitation, affects livelihoods, and increases the risk of fires and transmission of infectious diseases,” details the report of Lancet.
Political choices accentuate health crises
States themselves contribute to these health crises by subsidizing fossil fuels, note the researchers. Thus, 69 of the 86 governments analyzed (80%) subsidize the production and consumption of fossil fuels, for a net total of 400 billion US dollars in 2019.
“The carbon intensity of the global energy system [secteur qui contribue le plus aux émissions de gaz à effet de serre] decreased by less than 1% since the United Nations Framework Convention on Climate Change was established” (1992) and “at the current rate, full decarbonization of our energy system would take 150 years”note the researchers.
“The current strategies of many governments and corporations will lock the world into a fatally warmer future, tying us to the use of fossil fuels that are rapidly closing us off from the prospects of a livable world”laments to AFP Paul Ekins, professor of resources and policies at the Bartlett School of University College London.
The authors therefore call for a “health-centered response”. Thus, improving air quality would prevent deaths from exposure to fossil fuels, which number 1.3 million in 2020 alone. shifting to plant-based diets would reduce agricultural emissions by 55% and prevent up to 11.5 million annual diet-related deaths.