The sun’s power is weakening at its fastest rate in 9300 years, doubling the odds of a return to little ice age conditions by mid-century, according to research by the British Met Office.
The chance of a repeat of conditions that last occurred between 1645 and 1715 when London’s Thames River regularly froze over and became the scene of winter fairs, was now rated at between 15 and 20 per cent, up from 10 per cent in 2010.
The Met Office research says the fall in solar activity will not be enough to overwhelm global warming under the IPCC’s worst case scenario of 6.6C warming by 2100. However, under the IPCC’s less severe global warming scenarios, the Met Office said the changed solar activity was considered significant enough at a regional scale to warrant inclusion in climate models.
The role of solar activity in global warming has been controversial. The dominant view among climate scientists is that it is too small to have a major impact. On a global scale, the Met Office research found the impact from reduced solar output was a minor cooling effect of about -0.1C. “This is much smaller than the amount of warming expected due to greenhouse gases, which is several degrees for this experiment,” the Met said.
The cooling effect from weaker sunspot activity is expected to be much stronger in northern Europe, Britain and eastern parts of North America. Estimated cooling for northern Europe is in the range of -0.4C to -0.8C. This is because computer simulations expect cooling from weaker solar activity in these areas to be exacerbated by cold air from the Arctic, which shifts south due to changed wind conditions.