Night-time temperatures are more sensitive to climate change, a new study has found which explains why the nights have been warming much faster than the days over the last 50 years around the globe. Analysis of the causes of this more rapid warming at night shows this is likely to continue in the coming decades, said researchers. The study led by Richard Davy from Bjerknes Centre for Climate Research in Norway has examined the causes of the more rapid warming at night compared to the day, which has been seen around the globe in recent decades. Researchers analysed the causes of these changes from observations and model reconstructions of the climate in the 20th century. They showed that part of this more rapid warming at night is innate to the climate system, because night-time temperatures are inherently more sensitive to climate forcing. The layer of air just above the ground is known as the boundary-layer, and it is essentially separated from the rest of the atmosphere. At night this layer is very thin, just a few hundred metres, whereas during the day it grows up to a few kilometres. It is this cycle in the boundary-layer depth which makes night-time temperatures more sensitive to warming than the day, researchers said.