Climate change heating up nights faster than days, study finds
The increasing concentration of greenhouse gases in the atmosphere is causing the planet to heat up at an alarming rate, but it doesn’t do so in an entirely even way. A new study has found that climate change is raising nighttime temperatures across the globe faster than daytime temperatures, which could have “significant implications” for the environment, the authors warn.
While we know that some regions, such as the Arctic, are warming at a faster rate than others as a result of climate change, there has been little investigation into how the phenomenon might affect daytime and night time temperatures differently. And because different organisms carry out key tasks at different times of day (or night), the concern is that this kind of uneven warming could see some species feel the brunt of it more than others.
Scientists at the University of Exeter set out to find answers to these questions, turning to hourly records of temperature, cloud cover, specific humidity and precipitation to gauge the differences between nighttime and daytime temperature increases. This modeling was applied to the period of warming between 1983 and 2017, in which the team uncovered a difference in the mean annual temperature of more than 0.25 °C (0.45 °F) between night and day across more than half of the world’s land surface.
While in some locations days were seen to warm more quickly, the total area of regions experiencing greater nighttime warming was more than two times larger. According to the team, this asymmetrical warming phenomenon is being largely driven by shifts in cloud cover, with increased coverage helping to keep the land cool in the day and locking the warmth in at night. The opposite was true in places with decreased cloud cover, which led to faster-warming days.
"Warming asymmetry has potentially significant implications for the natural world," says lead author Dr Daniel Cox. "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."
Human activity is placing such a strain on global biodiversity that we saw a decline of 68 percent of vertebrate species between 1970 and 2016, according to a recent report from the World Wildlife Fund. While land clearing for food production was found to be the key driver of this species loss so far, experts anticipate enormous plant and animal losses as the climate changes and becomes unsuitable for many species across the globe.
The research was published in the journal Global Change Biology.