London: Scientists have come up with a theory to explain the strange, extended seasons – where summer or winter can last for years – in Game of Thrones.

The phenomenon could be explained by a so-called 'tumbling' of the tilt of the spinning axis of the planet as it orbits the sun.

This could occur in such a way that the same hemisphere always tilts towards the sun, they suggest.

Researchers from the universities of Bristol, Cardiff and Southampton used a model to simulate the climate of Game of Thrones.

They found that The Wall – where the land of Westeros is guarded from the White Walkers – has a winter climate similar to that of Lapland in Finland.

Casterly Rock – the stronghold of the scheming Lannisters – has a climate similar to Houston, Texas, and Changsha in China.

The researchers also modelled the global warming that would occur if concentrations of greenhouse gases in the atmosphere were to be doubled, due to increases in carbon dioxide and methane emissions from dragons and excessive use of wildfire.

"This work is a bit of fun, but it does have a serious side," said Professor Carrie Lear from Cardiff University.

"Climate models simulate real physical processes which operate in both cooling and warming climates."

The full results of the study have been published in a mock journal article, also available in Dothraki and High Valyrian, the fictional languages from the show.

Character Samwell Tarly, who is studying to become a 'maester' at the Citadel in Oldtown in Westeros, is listed as the author of the research.

The actual model simulations were carried out on the supercomputers of the Advanced Centre for Research Computing at the University of Bristol.

They were not funded in any way and were set up in the researchers' spare time.

PA