Humidity, not just heat, influences climate change

When it comes to measuring global warming, humidity, not just heat, is a factor in generating dangerous weather extremes, according to a new study.

The researchers say that temperature alone is not the best way to measure the effects of climate change and downplay its effects in the tropics.

But when you consider moisture in the air along with heat, climate change since 1980 is nearly twice what has been estimated before, according to the study published Monday in the scientific journal Proceedings of the National Academy of Sciences.

The energy generated in extreme weather, such as storms, floods, and rain, is related to the amount of water in the air.

So a team of scientists from the United States and China decided to use a little-known meteorological measure called the equivalent potential temperature (or theta-e), which reflects “the energy of the humidity of the atmospheresaid study co-author V. Ramanathan, a climate scientist at the Scripps Institution of Oceanography at the University of California, San Diego, and Cornell University. This measure is expressed in degrees, like temperature.

“There are two factors that influence climate change: temperature and humidity. Ramanathan pointed out. “And until now we measured global warming only in terms of temperature”.

By adding the energy of moisture, “extreme conditions—heat waves, precipitation, and other measures of extreme events—correlate much better”, he specified.

This is because, as the world warms, the air retains more moisture, almost 7% per degree Celsius (nearly 4% per degree Fahrenheit).

When that moisture condenses, it releases heat or energy, “that’s why when it rains, now it poursRamanathan said.

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

From 1980 to 2019, the world warmed 0.79° Celsius (1.42° Fahrenheit), but when energy from moisture is taken into account, the world has warmed 1.48° C (2.66° F), according to the study. And in the tropics, the warming was up to 4°C (7.2°F).

Judging by temperature alone, it appears that warming is most pronounced in North America, the mid-latitudes and especially the poles, and least in the tropics, Ramanathan said.

But this is not the case, since the abundant humidity that exists in the tropics increases the activity of storms, from the usual ones to tropical cyclones and monsoons.

“This increased latent energy is released into the air, leading to extreme weather events: floods, storms, and droughts.Ramanathan noted.

To Donald Wuebbles, a climate scientist at the University of Illinois who was not involved in the study, this makes sense because water vapor is key in extreme precipitation events. “Both heat and humidity are importantWuebbles said.