Global warming is heating up nights faster than days in most parts of the world, may affect wildlife: Experts
Global warming appears to be affecting nights and days differently. Nights are getting more heated up in many parts of the world, according to a new study that analyzed data from the last 35 years. Plants and animals may feel the pinch of the changing world, the findings suggest.
From 1983 to 2017, the mean annual temperature between daytime and night-time warming differed by more than 0.25 degrees Celsius, experts from the University of Exter said. They saw this trend in over half of the global land surface. However, certain regions have witnessed an increase in day-time temperatures. These regions have experienced twice the levels of overall warming, combined with reduced cloud cover and drying of the climate, the researchers wrote in their study.
"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. "We demonstrate that greater night-time warming is associated with the climate becoming wetter," he added.
The researchers factored in hourly records of temperature, cloud cover, specific humidity, and precipitation during the study period. Then, they modeled the different rates of change of daytime maximum and night-time minimum temperatures, and mean daytime and mean night-time cloud cover, specific humidity, and precipitation. They also looked at how vegetation growth and rainfall changed.
Europe, West Africa, western South America and central Asia are some regions seeing a higher night-time warming. Days were warming fasters in some regions like the southern US, Mexico, and the Middle East, the researchers found. These asymmetrical changes affect clouds. Overall, about 54% of the land surface has experienced warming asymmetry of greater than 0.25 degrees Celsius.
Regions with warmer nights are typically wet and have a reduced cloud cover. As a result, it blocks sunlight during the day. Still, the clouds retain heat to keep the night warm, thereby affecting vegetation growth.
Places that are seeing warmer days, on the other hand, are usually dry, according to the experts. Due to low water availability, vegetation growth is limited. "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," Dr Cox said.
This could be bad news for plants and animals alike as species carry out specific functions at a particular time of the day. The changes between night and day temperatures “will have profound consequences for the species inhabiting those regions and their ability to adapt in the face of the changing climate”, the scientists said. "Species that are only active at night or during the day will be particularly affected," Dr Cox added.
“While it’s too early to determine the impact on any individual species, this potentially significant finding provides further evidence of the imbalances being forced on nature by humankind," Mark Wright, the director of science at WWF-UK, told The Guardian.“We know we need to take urgent action to halt and reverse humanity’s impact on nature, including rapid and deep cuts to greenhouse gas emissions.”
The study is published in Global Change Biology.