Future lows in solar activity could affect winter temperatures in northern Eurasia and the eastern United States according to a study published in Nature Communications. Solar activity, which determines the amount of ultraviolet (UV) radiation that reaches the Earth, varies over time.

Until recently, the Sun was in the midst of a period of relatively high activity, a grand solar maximum; however, lower than average activity over the past few years suggests this maximum might be coming to an end. Grand solar minima have been shown to coincide with severe winters in the UK and Europe, with frost fairs on the River Thames a common occurrence during the Maunder Minimum (1645-1715). Statistical forecasts indicate a 15-20% chance of a return to Maunder Minimum-like activity within the next 40 years and, while the effect on global temperatures is thought to likely be quite small, regional effects are larger.

To investigate the possible regional impact of a future Maunder Minimum scenario, Sarah Ineson and colleagues conduct two experiments to cover the range of future possible decreases in UV radiation. Although it is not enough to counter climate change, they show that future winters in northern Eurasia and the eastern United States could experience temperature drops of up to 0.75°C. The model results also suggest a southward shift in winter rainfall towards southern Europe and an increase in the number of frost days in Northern Europe and the southeast United States. While these changes should be considered a high estimate, the results suggest that changes in solar activity should be considered, alongside greenhouse gases, when generating future climate forcing scenarios.