Day-night temperature gap is shrinking due to climate change: study

The deviation, called diurnal temperature range, is considered crucial as it has a significant impact on crop yields, change of seasons and human health issues related to heat stress, etc.

The study was published in Geophysical Research Letters, a bi-weekly peer-reviewed geoscience journal. Representative picture

Clouds, the atmospheric blanket that envelops the earth, offer us respite from the heat, in addition to bringing us rain. Clouds also have another significant impact on our daily lives, according to a team of researchers in the United States.

Their study, published in Geophysical Research Lettersa bi-weekly peer-reviewed geoscience journal published by the American Geophysical Union, found that the difference between daily maximum and minimum temperatures across the globe is shrinking due to climate change-induced increased cloud cover .

The difference between the daily maximum and minimum temperatures is called the daytime temperature range (DTR). DTR is considered crucial as it has a significant impact on crop yields, changing seasons, and human health issues related to heat stress, etc.

How Cloud Cover Affects DTR

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The research team, in their attempt to decipher the DTR shrinking phenomenon, listed some factors that influence regional temperatures – changes in land use, soil moisture, precipitation, cloud cover, etc. . – and simulated their effects on climate change, using supercomputers. .

The team was able to perform in-depth analysis of the complex interplay between land surface processes and climate change, as the simulation helped them create a finer-resolution climate model, the first of its kind, with grids of two square kilometers instead of the commonly used model. 100 kilometer grids.

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The Kanto region of Japan and the Malaysian peninsula were chosen as the two areas of interest for the model. Using the period 2005-2014 as the reference decade, the researchers ran different climate scenarios to project how the DTR in the two target regions will change by the end of the century.

The temperature gap narrowed by around 0.5°C in the temperate Kanto region and 0.25°C in the more tropical Malaysian Peninsula, later results showed. These changes have been largely attributed to the increase in daytime cloud cover that is expected to develop under these climatic conditions.

Why the impact of DTR is crucial

According to Doan Quang Van, the lead author of the paper, “Clouds play a vital role in diurnal temperature variation by modulating solar radiative processes, which consequently affect heat exchange at the surface of Earth”.

Simply put, an increase in cloud cover reduces incoming shortwave solar radiation during the day. This lowers daily maximum temperatures, helping to close the gap between daily high and low temperatures.

Climate projections, however, indicate that daily high and low temperatures will continue to rise due to climate change, although the former will do so at a slower rate.

With the shrinkage of the DTR also certain, a better understanding of its impacts can allow us to be better prepared to deal with the threat of global warming. “It is very important to know how DTR will evolve in the future because it modulates human, animal and plant metabolism. It also modulates local atmospheric circulation, such as the land-sea breeze,” Quang Van added.

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Geophysical Research Letters was established in 1974. Its current editor, Harihar Rajaram, is a professor of environmental health and engineering, who uses mathematical models to shed light on complex environmental and earth systems and to predict future trends within these systems.

Rajaram received his doctorate from the Massachusetts Institute of Technology in 1991. His recent research has explored the environmental impacts of hydraulic fracturing, including man-made earthquakes resulting from the injection of fracturing fluids into deep geological formations. , the biogeochemical impacts of global warming in alpine regions. and other environments, and the response of glaciers and ice caps to global warming – research that sheds light on the subtle effects of climate change on public health.

Teresa H. Sadler