Number of days with “dangerous” heat threatens to increase significantly by 2050 | Environment

The study, led by Lucas Vargas Zeppetello of the University of Washington in Seattle, is published in the journal “Communications Earth & Environment”.

The scientists used the heat index of the American weather service NWS for the study. It uses a kind of wind chill that takes into account the effects of temperatures and relative humidity on humans. From a wind chill of 39.4°C becomes a weather situation on that heat index if “dangerous” considered, from 51.1°C even if “extremely dangerous”.

For the future projections, the scientists have based themselves on climate models that take into account, among other things, projections for the development of the population and of the GDP of individual countries and regions. The amount of CO . was also taken into account₂ emitted by various industries. On this basis, a favorable, an unfavorable and an average scenario was drawn up.

Even if the goals of the Paris climate agreement are achieved – limiting global warming to less than 2°C – the researchers expect three to ten times as many days of sunlight by 2100 in the US, Western Europe, China and Japan. dangerous weather as in comparable periods between 1979 and 1998.

In an average scenario – a three-degree increase in the average global temperature from the pre-industrial period – in the tropical and subtropical climate zones, the threshold of 39.4 degrees from 2050 would be on a quarter to half of all days. are being reached.

In fact, by the end of the century, in many of the tropical and subtropical regions, this would be the case on most days. This would mainly affect Sub-Saharan Africa, the Arabian Peninsula and India. Even the “extremely dangerous” heat index class would be reached more than 15 days a year in those regions.