Global warming: it’s not only heat, but also high humidity

(ORDO NEWS) — The energy generated in extreme weather conditions such as storms, floods and precipitation depends on the amount of water in the air.

A new study shows that when it comes to measuring global warming, humidity, not just heat, matters in creating dangerous climate extremes.

The researchers say temperature isn’t the best way to measure strange climate-related weather, downplaying the effects of changes in the tropics.

But accounting for air humidity along with heat shows that climate change since 1980 has worsened the situation twice as much as previously calculated. This is reported in a study published on Monday in the journal Proceedings of the National Academy of Sciences.

The energy generated in extreme weather conditions such as storms, floods and precipitation depends on the amount of water in the air.

So a team of scientists from the US and China decided to use a little-known weather parameter called Equivalent Potential Temperature, which reflects the “moisture energy of the atmosphere,” said study co-author V. “Ram” Ramanathan of the Scripps Institution of Oceanography of California. university.

“There are two causes of climate change: temperature and humidity,” Ramanathan said. “And so far, we’ve only measured global warming in terms of temperature.”

But when we start accounting for humidity, “extreme conditions like heatwaves, precipitation and other extremes correlate much better,” he said. “When this moisture condenses, it releases heat or energy.”

In addition, water vapor is a powerful gas that traps heat in the atmosphere, which amplifies climate change, he said.

From 1980 to 2019, the world warmed by about 1.42 degrees (0.79 degrees Celsius). But taking into account the energy of humidity, the world warmed up and became humid by 2.66 degrees (1.48 degrees Celsius), the study said. And in the tropics, warming was as much as 7.2 degrees (4 degrees Celsius).

Judging by temperature alone, warming is most pronounced in North America, in the mid-latitudes and especially at the poles, and to a lesser extent in the tropics, Ramanathan said.

But that’s not the case, he said, because high humidity in the tropics amplifies storm activity, from normal storms to tropical cyclones and monsoons.

University of Illinois climate scientist Donald Webbles, who was not involved in the study, said it makes sense because water vapor plays a key role in extreme precipitation. “Both heat and humidity are important,” said Webbles.

Environmental scientist Katherine Mach of the University of Miami, who was not involved in the study, said: “Humidity plays a key role in shaping the impact of heat on human health and well-being now and in the future.”

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