Killer combination of heat and humidity or “humid-heat” waves, not experienced before by humans, are already ravaging the world and is becoming more common, contrary to climate studies that suggested these extreme impacts are still decades away.
Friday, a new report released by The Earth Institute at Columbia University indicates this weather mix, mostly fatal, is exceeding the theoretical human survivability limit and increasingly testing our limits well into the future.
High abnormal temperatures coupled with stifling humidity have already caused massive death tolls. Events like these are becoming more common and more intense as the planet becoming warmer day by day.
“Climate change is increasing both air temperatures and the amount of moisture in the air, making humid heat events more frequent and severe” Radley Horton, a Columbia University research scientist and co-author of this study tells CNN Weather.
This study looked directly at hourly data captured by nearly 8,000 weather stations instead of average temperature and humidity, generally considered by previous studies over longer durations and larger areas.
The previous studies could not capture the extreme nature of the heat stress as temperature and humidity spikes can occur in only a few hours and specific locations such as a densely populated neighborhood within a coastal city.
“I was astonished by our findings,” the author of the study tells CNN Weather. “My previously published study projected that these conditions would not take hold until later in the century.”
“We may be at a closer tipping point than we think,” Horton says.
“Climate change is increasing both air temperatures and the amount of moisture in the air, making humid heat events more frequent and severe.”
Literally off the charts readings
The “wet bulb” temperature, used by the meteorologists, combines heat and humidity to asses discomfort levels similar to the heat index.
Virtually it’s impossible to carry on outdoor activities when a wet-bulb temperature reaches 32 degrees Celsius that is equivalent to 132 degrees Fahrenheit on the heat index. Any temperature exceeding 35 degrees Celsius (the theoretical survivability limit), is presumed “outside the range of natural variability.”
This temperature is equivalent to a heat index of 160F, which is quite literally off the National Weather Service’s Heat Index charts.
The wet-bulb readings of 30 degrees Celsius or higher have become double worldwide since 1979, the study reveals, with readings across the Persian Gulf topping the potentially lethal 35 degrees Celsius limit.
The proximity of coastal cities to evaporating seawater makes them more vulnerable to the effects of heat stress. People who live along the Gulf Coast of the US are well aware of the heat and humidity combination that can make even the simplest outdoor tasks unbearable.
New Orleans and Biloxi, Mississippi, have experienced extreme conditions several times along with their neighbors in the Florida Panhandle and into eastern Texas, the study found.
Inland locations, even if they are not on the immediate coastline, can also be hotbeds for heat stress. Horton tells CNN Weather that “extreme water temperatures can prime the pump for deadly humid heat events in nearby land areas.” As local winds can transport this moisture-rich air inland, it is similar to what is experienced throughout low-lying river deltas during the monsoon season in India.
Too hot to resist
Human bodies cool themselves by sweating, but this process becomes less effective if the humidity is high. That is why we instinctively seek out shade or air-conditioned buildings.
It’s not that easy elsewhere, according to Ryan Maue, a research meteorologist in the private sector who is not part of the group of researchers responsible for the study.
“This is not a problem for the end of the century, but in the present, especially in the developing world without widespread air conditioning,” Maue says.
In poorer countries, many people even struggle to receive reliable electricity, let alone air conditioning for their homes.
The most vulnerable locations, such as southern Asia, subtropical Africa, the Caribbean, northwest Australia, coastal southwest North America, and the Persian Gulf, have been identified in this latest report.
The highest heat and humidity readings were recorded 14 times throughout Persian Gulf cities that include Doha, and also Qatar, which will host the FIFA World Cup in 2022, according to their research. Event organizers had no choice but to move the tournament to the cooler months of November and December that the experience of brutal heat during typical World Cup months of play could be avoided.
Several recent studies, including the present one, have concluded that global warming will soon reach levels that make human survival difficult, if not impossible.
If the current levels of warming of the planet continue for the next 50 years, it is estimated that up to 3 billion people could be living in areas with hot temperatures beyond human tolerance limit.
