Winter is not coming: man-made climate change is wiping out seasonal temperature differences

Mankind may be responsible for something we long thought out of our control: the changing of the seasons, according to a new study by Chinese and Canadian scientists.

For the first time, researchers have found evidence that man-made climate change has suppressed the natural fluctuation of seasonal temperatures in the northern hemisphere, removing the distinction between summer and winter.

In the most affected regions, the gap between the mean temperature in summer and winter has been narrowing at a rate of more than 0.1 degrees celsius per decade since the 1950s, according to the study published in the American Meteorological Society's Journal of Climate.

If the trend persists, winter in Beijing – which currently drops below freezing - could be as warm as the summer in 3,000 years.

Such a scenario was long thought impossible. Seasons, as defined in textbooks, are caused by the tilt of the earth as it orbits around the sun, with different amounts of heat and light falling on different regions throughout the year.

But that is not the whole story. The orbit and tilt of the planet do not explain why Antarctica, which has always received the least amount of sunlight, was once warm and covered in thick forest.