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The night is heating up faster than the day, new study finds


A recent study of temperature, cloud cover and precipitation around the world found that the nights have warmed more than the days. These results also reveal important data on wildlife.

Climate change affects nighttime temperatures more than daytime temperatures.

Global warming affects daytime and nighttime temperatures differently. Thus, nocturnal warming is more important than daytime warming in the world, according to a recently published study.

Scientists at the University of Exeter studied global warming trends from 1983 to 2017, looking at hourly records of temperature, cloud cover, humidity and precipitation.

They found an average annual temperature difference of more than 0.25 ° C between daytime and nighttime warming over more than half of the world's land surface. The days have warmed up more quickly in some places while it has been the nights in others, but the total area of ​​nocturnal warming is still larger, on the order of about twice.

The study shows that this effect, dubbed "warming asymmetry" by researchers, is mainly due to changes in cloud cover levels.

Increased cloud cover cools the surface during the day and retains heat at night, resulting in more nocturnal warming. In contrast, less cloud cover allows more heat to reach the surface during the day, but that heat is lost at night.

Impacts on nature

The warming asymmetry has potentially important consequences for the natural world, especially for wildlife that is only active at night or in daylight, according to lead author Dr Daniel Cox of the Institute. environment and sustainability at the Exeter Penryn campus in Cornwall, South West England. On social media, Dr Daniel Cox shared the study recently published in the academic journal "Global Change Biology", before tweeting: "Our latest article showing that more than twice the land area in the world has experienced a nocturnal warming greater than daytime warming is getting good media attention. "

“We thus demonstrate that greater nocturnal warming is associated with the climate becoming wetter, and this has been shown to have important consequences for plant growth and for the way in which species, such as insects. and mammals, interact, ”he also said.

In plants, increasing nighttime minimum temperatures is expected to affect carbon uptake and uptake, as most photosynthesis occurs during the day and is more sensitive to daytime maximum temperatures, the research shows.

In animals, greater diurnal warming results in drier conditions, combined with higher levels of global warming, increasing the vulnerability of species to heat stress and dehydration, he said. Tropical species are particularly vulnerable to small increases in temperature because they have evolved under relatively constant and stable climatic conditions, and live closer to their optimum temperature, the scientists also noted.