On the present emissions pathway, it’s likely that the world will hit 4 degrees Celsius warming by 2100. And this level of warming will be enough to bring on heatwaves so hot that staying outside for even brief periods will be deadly. Such unimaginably severe heatwaves will affect heavily populated regions such as Eastern Europe, the U.S. East Coast, coastal China, India, and South America with bi-annual frequency.
(Probability that summer heat index values will exceed 40 C [104 F] and 55 C [131 F] under 1.5, 2 and 4 C warming. Note that biannual frequency of 55 C heat indexes over large regions under 4 C warming implies that strong heatwaves would be considerably more severe. Image source: Superheatwaves of 55 C Emerge if Global Warming Continues.)
These were the findings of a ground-breaking new report produced by Europe’s Joint Research Center. The report notes that many of these heatwaves will combine very hot air and high humidity to produce deadly conditions — implying wet bulb readings in the range of 35 degrees Celsius or the threshold for human survivability over densely populated regions. Such high levels of heat would be both crippling and life-threatening — bringing activity in these areas to a grinding halt, spiking cooling based energy demand, and making it impossible to stay in non climate controlled environments for more than very brief periods.
The report predicts that the rising global temperatures, due to fossil fuel burning, will bring about this new brand of super heatwave afflicting many of today’s most populated cities:
However, if temperatures rise to 4°C a severe scenario is on the horizon. Scientists predict that a new super-heatwave will appear with apparent temperature peaking at above 55°C– a level critical for human survival. It will affect densely populated areas such as USA’s East coast, coastal China, large parts of India and South America. Under this global warming scenario Europe is likely to suffer annual heatwaves with apparent temperature of above 40°C regularly while some regions of Eastern Europe may be hit by heatwaves of above 55°C.
55 degrees Celsius translates to 131 degrees Fahrenheit. Today’s Death Valley summer temperatures typically range between 115 and 120 F. By comparison, the hottest temperature ever recorded on Earth, according to Christopher C. Burt from Weather Underground is presently 129.2 degrees Fahrenheit. But under continued fossil fuel regimes, apparent temperatures or heat indexes exceeding those very high values will occur with a very high regularity. That means it will feel like it’s hotter than Death Valley. Hotter than today’s highest ever recorded temperatures.
(Heatwaves like the one dubbed ‘Lucifer’ in Europe this year are just a mild foreshadowing of what’s to come if humans continue burning fossil fuels. Image source: Tropical Tidbits.)
Such heatwaves would regularly dwarf the impacts of today’s multi-billion dollar disasters like the heatwave dubbed Lucifer that impacted Europe this year. But the study authors note that even their worrying estimates may be conservative.
The report’s press release goes on to state that:
According to the study, the effect of relative humidity on heatwaves’ magnitude and peak might be underestimated in current research. The results of the study support the need for urgent mitigation and adaptation action to address the impacts of heatwaves, and indicate regions where new adaptation measures might be necessary to cope with heat stress.