A new report released Friday by the Earth Institute at Columbia University indicates that the combination of extreme heat and humidity, once thought never experienced by humans, is already happening. This often fatal meteorological mix is crossing the theoretical threshold of human survival and will increasingly test our limits also in the future.
“Climate change is increasing both the air temperature and the amount of humidity in the air, making humid heat events more frequent and severe,” Radley Horton, a Columbia University researcher and co-author of this study, says CNN Weather.
What sets this study apart is that it directly looked at hourly data acquired from nearly 8,000 weather stations, while previous studies typically averaged temperature and humidity over longer durations and larger areas. Since peaks in temperature and humidity can only occur in a few hours and in specific places (such as a densely populated neighborhood within a coastal city), previous studies have failed to capture the extreme nature of thermal stress.
“I was amazed at our findings,” says the author of the study at CNN Weather. “My previously published study projected that these conditions would not occur until the turn of the century.”
“We may be at a point of no return closer than we think,” says Horton.
“Climate change is increasing both the temperature of the air and the amount of humidity in the air, making the events of humid heat more frequent and serious.”
The readings were literally off the scale
Meteorologists use the temperature of the “wet bulb” which, similar to the heat index, combines heat and humidity to evaluate the levels of discomfort.
Outdoor activities are practically impossible when a wet bulb temperature reaches 32 degrees Celsius – the equivalent of 132 degrees Fahrenheit on the heat index. Something above 35 degrees Celsius (the theoretical survival limit) is considered “outside the range of natural variability”.
This equates to a heat index of 160F, which is literally outside the National Weather Service’s heat index rankings.
Since 1979 wet bulb readings of 30 degrees Celsius or higher have doubled worldwide, the study reveals, with readings across the Persian Gulf on top of the potentially lethal limit of 35 degrees Celsius.
Coastal cities are more vulnerable to the effects of thermal stress due to their proximity to the evaporation of seawater. If you live along the Gulf Coast of the United States, you are well aware that the combination of heat and humidity can make even the simplest outdoor activities unbearable.
The study found that New Orleans and Biloxi, Mississippi, have experienced extreme conditions dozens of times together with their neighbors in the Panhandle of Florida and eastern Texas.
Too hot to handle
Our bodies cool down by sweating, but if the humidity is high, this process becomes less effective. So we instinctively look for shady or air-conditioned buildings.
It’s not so easy elsewhere, according to Ryan Maue, a private sector research meteorologist who isn’t part of the team of researchers responsible for the study.
“This is not a problem for the turn of the century, but in the present, especially in developing countries without widespread air conditioning,” says Maue.
Many people in poorer countries find it difficult to receive reliable electricity, much less air conditioning for their homes.
The most vulnerable locations identified in this latest report include southern Asia, subtropical Africa, the Caribbean, northwestern Australia, coastal southwestern North America and the Persian Gulf.
This study is one of several recent studies that have reached similar conclusions; global warming will soon reach levels that make human survival difficult if not impossible.
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