The heat related mortality it has been identified as one of the main climatic extremes that pose a risk to human health. Current research focuses mainly on how this mortality increases with increasing global average temperature.
However, these changes are strongly driven by extreme events that become more frequent and intense, hitherto invisible, that reach unexplored territories.
This is according to a new study published in Nature Communicationled by Swiss research centers and in which the researcher Dominic Royé from the Foundation for Climate Research (FIClima) participates, where the changes in the frequency of extreme heat events and the associated mortality.
Heat mortality of a one in 100 year event at the beginning of this century is expected once every ten to twenty years in today’s climate
Through a probabilistic analysisthe authors combine, on the one hand, the relationships between heat and mortality to 748 locations from 47 countriesand on the other, data from large sets of climate modelsto identify probable past and future high-impact summer events.
Thus, in most places, a heat mortality event of one every 100 years in the year 2000 or early this century would be expected once every ten to twenty years in 2020 or today’s climate.
Under these conditions it is expected that these return periods are shortened even lower levels of warming 1,5 °C y 2 °Cwhere the heat mortality extremes of the past climate will eventually become commonplace if no adaptation occurs.
The results underline the urgent need for strong mitigation and adaptation to reduce the impacts on human life.
Given that the effects are not linear, both in the new climatic extremes and in the vulnerability to heat of the population, it should be expected unprecedented impacts on human healthespecially among the most disadvantaged, if it is assumed that there is no adaptation.
The study’s conclusions underscore the urgent need for strong mitigation and adaptation to reduce impacts on human life.
The examples of Paris and Barcelona
As an example, while the summer of 2003, with an excess mortality of 2,700 people only in Parisit was a very rare event that occurred once every 100 years, in the current climate it is expected to be an event every 18 years and every four years in a world of 2°C global warming.
At the same time, mortality caused by future summers in Paris with unprecedented intensities doubles in a world with 1.5°C and almost triples in a world with 2°C without adaptation.
An extreme summer event that occurred one in every 100 years in Barcelona, its frequency was one every 10 years in 2020 and with global warming of 2ºC it would be expected every two years
In Spain, an extreme summer event that in the recent past could occur one in every 100 years, currently in Barcelona, for example, its frequency has increased to one every 10 years in 2020, and even with global warming of 2ºC would be expected to be 1 every 2 years.
Thus, heat-attributable mortality from a secular event would go from 7.4% in 2020 to 13% in a world of 2°C global warming.
Mortality attributable to heat from a secular event would go from 7.4% in 2020 to 13% with 2°C of global warming
With this approach, it is possible to quantify the direct potential impact of climate change in human health. Results at the city level are more practical for decision makers such as public health authorities.
This information can also be very useful for decision makers, in order to prepare for the extreme conditions of the future. In this way, it will be possible to give the opportunity to a better adaptation and vulnerability reduction, which is the most important final application of the study.
Changes in the return periods of a secular event at the 748 locations. Changes in return periods for the 2020 climate (1.2°C warming level, a), at 1.5°C warming (b), and at 2.0°C warming (c) compared to the risk in the climate of 2000 (0.7 °C warming). / Samuel Lüthi et al./Nat. commun.
Rights: Creative Commons.
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