Stonehenge
The sun rises behind Stonehenge as revellers celebrate the summer solstice in Wiltshire. Scientists warn its power output might be dimmingGetty

The sun's energy output is the lowest it has been for about 300 years when the River Thames froze over , but this will not stop global warming, scientists have warned.

Scientists at the British Met Office Hadley Centre said the drop in output would affect temperatures in Europe and eastern North America.

The study said solar output was falling from high levels in recent decades and there was a 15-20% chance of a decline by 2050 to match the "Maunder Minimum" of 1645-1715. This could cause a 0.1 Celcius drop in average global temperatures, the scientists estimated.

"We can't be saved by the sun, unfortunately," Professor Adam Scaife, a co-author at the Met Office Hadley Centre in Britain, told Reuters, commenting on the report published in the journal Nature Communications.

Scaife added: "Although the effect on global temperatures is very small, the local effect is big enough to make a difference and we need to include that in our future climate projections."

Scaife warned: "There is a high chance that solar activity of the sun will decrease over the next few years. There is a chance of a repeat of the Maunder Minimum period where sun spots completely vanish, there are already some signs of this.

"This can change the amount of ozone in the atmosphere over the tropics and a weakening and southwards shift of the jet stream, in winter this leads to colder conditions. There were many factors which triggered the winter of 2009/10 and this could have been one of them.

"We might get another year when all these factors come together again, in any case there is an increased risk of colder winters."

Met Office scientist and lead author Sarah Ineson, said: "This shows that the regional impacts of a grand solar minimum are likely to be larger than the global effect. This study shows that the sun isn't going to save us from global warming, but it could have impacts at a regional level that should be factored in to decisions about adapting to climate change for the decades to come."