Nocturnal warming: the nights are heating up faster than the days
The nights are getting hot, but it's not exactly fun.
There’s a global warming asymmetry that you might not be aware of.
We tend to think of global warming as a singular, individual phenomenon, but the truth is the impacts of the changing climate vary greatly across lattitudes and different areas. Because of this, many of the effects of global warming fly under the radar — for instance, we only directly observe what’s happening on land, and we pay less attention to ocean warming (although oceans have absorved 93% of man-made greenhouse gases). Similarly, we’re inclined to pay less attention to what goes on at night.
But according to a recent study, we’d be wise to pay more attention.
The nights, researchers found out, are heating up by more than 0.25°C compared to the days. The change wasn’t uniform — in some areas, days warmed more quickly than in others, but overall, the night-time heating was twice as large for the studied period (1983-2017).
The reason, researchers suspect, has to do with cloud cover. Clouds cool the surface during the day but maintain heat during the night — so if you get more clouds, your nights will heat up more.
The findings could be very important for human activity as well as ecosystems. For instance, the differences between daytime and nighttime vegetation growth depend on rainfall and temperature, and this vegetation supports entire ecosystems. Hotter temperatures put extra stress on species, and those that are active during the night will be particularly affected, the researchers say.
“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, and this has been shown to have important consequences for plant growth and how species, such as insects and mammals, interact.”
Over half of the global land area has experienced diurnal asymmetry in warming of more than 0.25°C, and this phenomenon will have profound consequences for the species inhabiting those regions and their ability to adapt in the face of the changing climate, Cox also adds. By understanding this type of differential warming we can better prepare for climate change — especially when it comes to drawing conservation plans for ecosystems or individual species.
