UAE temperatures rising faster at night than during the day, researchers find

Climate change is causing temperatures in the UAE to increase more during the night than during the day, a new study has found.

The scientists behind the research have also warned that extreme rainfall events in the country are going to become more common.

Set for publication in Nature Scientific Reports, the findings are the latest to highlight how global warming is likely to make the region’s climate more extreme.

“Higher night-time temperatures will likely further exacerbate the mugginess in a region where the combination of heat and humidity at times exceeds the threshold for human habitability,” the paper states.

Night-time temperatures are going to increase faster than those during the day because, with global warming, low-level cloud cover is increasing, said Dr Diana Francis, an assistant professor at Khalifa University in Abu Dhabi and the first author of the study.

Higher levels of atmospheric moisture, caused by increases in evaporation as temperatures rise, and of dust, the result of continued desertification as arid areas spread, are prominent causes of this.

The larger amount of low-level cloud cover, which is likely to be seen over north-eastern Africa and the Arabian peninsula, especially in the summer months, will act as a drag on average temperature increases during the day, but will also limit the extent to which the air cools at night.

“These type of clouds reflect the sunlight back into space during the day and have a cooling effect, but act as a blanket during night because they absorb and re-emit heat back down to the Earth’s surface at night,” Dr Francis said.

The trend of temperatures increasing more at night than during the day is particularly evident during the summer, according to the paper.

Dr Francis is head of the Environmental And Geophysical Sciences Laboratory at Khalifa University, another member of which, Dr Ricardo Fonseca, is also an author of the paper.

‘Ultra-extreme heatwaves’

While night-time temperatures may increase at a faster rate, the study warns there will be significant increases in maximum temperatures, which are typically experienced during the day.

The paper highlights previous research, published in 2021, that indicated that under a “business as usual” climate change scenario, meaning that additional measures to cut carbon emissions are not taken, the Mena region could experience “ultra-extreme heatwaves”.

Dr Diana Francis, who is a climate researcher at Khalifa University. She has published many papers on climate change. Antonie Robertson/The National

“Half of the population in the Mena region (roughly 600 million people) could be exposed to recurring super and ultra-extreme heatwaves, which will feature air temperatures up to 56ºC and higher lasting for several weeks at a time, in the second half of this century,” the paper said.

As temperatures increase, evaporation becomes stronger, which results in greater moisture content in the atmosphere.

The paper warned that this will “promote more extreme precipitation events”, raising the prospect that heavy rains of the kind that caused severe flooding in the UAE will happen more often.

Earlier this month there was severe flooding after some parts of the UAE received more than 250mm of rain in a 24-hour period, the most in the country’s history.

“Extreme rainfall events in countries located in the current subtropics are expected to be on the rise, both in frequency and intensity, due to global warming,” Dr Francis said.

The paper also indicates that the size of arid areas in the Mena region are set to continue increasing, in part because of climate change.

“The arid and semi-arid regions over northern Africa and south-west Asia have been expanding in the last several decades with their impacts aggravated by the rapid population growth and they are likely to become even more extreme in a warming climate,” the paper said.

Numerous researchers have analysed climate change trends in the Middle East and they have identified a number of trends.

Overall in the Middle East, temperatures are on average rising faster than they are in the rest of the world, according to Prof Jos Lelieveld, a climate researcher at the Max Planck Institute for Chemistry in Germany and The Cyprus Institute.

Prof Lelieveld, who was not part of the latest study, said a key factor for this is that, with much of the region being desert, there is little moisture in the soils.

Other regions typically have higher levels of soil moisture, and this absorbs solar energy when it changes from liquid to gas during evaporation, which limits temperature increases.

Another trend, evident in the region as a whole, he said, is that temperatures are rising more in summer than they are in winter.

“The temperature trend is really fast in the summer,” Prof Lelieveld said. “Overall the temperature trends are much faster than in most other parts of the world.”