Global Warming Is Making Nights Hotter Than Days, As Per 34 Years Of Data

A new study by scientists warns of a "warming asymmetry" between the days and nights on Earth due to global warming. As per the study, night-time temperatures have increased more than the day-time temperatures over the past years.

NASA Earth Observatory

To come to this conclusion, scientists from the University of Exeter studied warming from 1983 to 2017. The global study involved the examination of hourly records of temperature, cloud cover, specific humidity and precipitation.

In their study, now published in the journal Global Change Biology, they found a difference in mean annual temperature of more than 0.25°C between daytime and night-time warming. The pattern was observed in over half of the global land surface.

The study highlights how global warming is affecting daytime and night-time temperatures differently. It mapped that while the daytime temperatures rose in some areas more quickly, other locations saw night-time temperatures soaring higher.

(Image: NASA)

The total area of disproportionately greater night-time warming, however, was more than twice as large.

Global warming asymmetry

As per the study, the warming asymmetry between the day and night on Earth can be accredited to changing levels of cloud cover.

During the day, an increased cloud cover keeps the surface cool. However, the same cloud cover can entrap heat at night, raising the nighttime temperature.

The reverse scenario also holds true, as a decreasing cloud cover allows more heat from the sun to reach the surface during the day raising the temperature, but that warmth is lost at night.

"Warming asymmetry has potentially significant implications for the natural world," said lead author Dr Daniel Cox, of the Environment and Sustainability Institute on Exeter's Penryn Campus in Cornwall, in a release.

Difference between day and night on Earth, as observed from the International Space Station (Image: NASA)

"We demonstrate that greater night-time warming is associated with the climate becoming wetter, and this has been shown to have important consequences for plant growth and how species, such as insects and mammals, interact.”

"Conversely, we also show that greater daytime warming is associated with drier conditions, combined with greater levels of overall warming, which increases species vulnerability to heat stress and dehydration.”

"Species that are only active at night or during the day will be particularly affected," warns Cox.