Climate change predictions are overly gloomy because plants are better at removing carbon dioxide from the atmosphere at night than previously thought, according to a new study.

Scientists believe current models of global warming fail to take into account the extent to which plants absorb carbon dioxide in the dark.

They have also said that soil loses less nitrous oxide - also bad for the climate - at night than previously thought.

Mankind currently emits roughly 34 gigatons of CO2 a year, roughly half of which remains in the atmosphere, with the rest either absorbed by the oceans or by the land, known as the terrestrial carbon sink (TCS).

The TCS can account for up to 11 gigatons a year.

A team at the US Department of Energy found that by not properly accounting for what plants do at night and during the non-growing season, climate models may be underestimating the terrestrial carbon sink and overestimating nitrous oxide release, the latter by 2.4 gigatons of CO2-equivalent per year.

"This number is substantial compared to the current terrestrial carbon sink," said Dr William Riley, who led the study.

"This is goodish news, with respect to what is currently in the climate models. "But it's not good news in general - it's not going to solve the problem.