What impact would a ‘grand solar minimum’ have on our future climate?

Tuesday 23rd Jun 2015 by theWeather Club

Image: Extreme Ultraviolet Imaging telescope (EIT) image of the sun taken in 1999 (Source: NASA)

A paper, led by Met Office scientists in collaboration with the universities of Cambridge, Oxford, Reading and Colorado and published in Nature Communications, has explored the potential regional impacts of a drop to solar activity not seen in centuries. The study found that the return of a ‘grand solar minimum’ could increase the chances of cold winters in European and Easter US, but wouldn’t halt global warming.

Variability in the sun’s output is measured by the number of sunspots on its surface, over a period of 100-200 years. Some solar physicist believe there’s an increased risk that we are heading towards this minimum stage of this solar cycle – last seen during the so-called ‘Maunder Minimum’ which ended 300 years ago and coincided with colder winters in UK and Europe. 

Climate scientists have been investigating the impact this would have on global temperatures using a climate model to simulate conditions from 2050 to 2099, using the RCP 8.5 scenario (a socio-economic scenario which assumes ‘high-end’ future carbon concentrations) and reducing solar output to Maunder Minimum levels.

The findings from this study indicates that the global impact from decreased solar output was relatively small (a cooling effect of around -0.1oC), and much smaller than the amount of warming expected as a result of greenhouse gases (several degrees for this particular experiment).

Regionally, a larger cooling effect was found for northern Europe, the UK and eastern parts of North America, especially in winter, with Northern Europe seeing a mean drop in temperature in the range -0.4oC to -0.8oC. However, winters at that time are projected to be warmer overall, but this work indicates that an increase in the risk of colder winters during this time. 

The impact of a grand solar minimum would therefore only temporarily moderate future warming from climate change.

Sarah Ineson, a Met Office scientist and lead author of the research, said, “This research shows that the regional impacts of a grand solar minimum are likely to be larger than the global effect, but it’s still nowhere near big enough to override the expected global warming trend due to man-made change. This means that even if we were to see a return to levels of solar activity not seen since the Maunder Minimum, our winters would likely still be getting milder overall.” 

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.”

Amanda Maycock, a scientist at the University of Cambridge and National Centre for Atmospheric Science, added: “Given the outlook for solar activity from some experts, it’s important that we consider the potential impact of changes in UV output when looking at future climate.”

Read the full journal article here >>