A return to a ‘grand solar minimum’ not seen for centuries may cause some cooling but won’t outweigh greenhouse effect
Telescopic image shows solar magnetic field rising vertically from a sunspot into the atmosphere (Hinode JAXA/NASA)
By Alex Pashley
Lower solar output could make cold winters in Europe and eastern parts of the United States more likely, but won’t cancel out global warming, new research reveals.
Physicists believe solar activity ebbs and flows over a timescale of 100-200 years.
And we might be headed towards the lower end of the cycle, according to research by the UK’s Met Office published in Nature Communications on Tuesday.
That was last seen during the ‘Maunder Minimum’ from about 1645 to 1715, when sunspots – storms on the star’s surface that lead to solar flares and belch out gases – were few.
The findings dent claims by some climate change sceptics that it is solar activity – not greenhouse gas emissions – responsible for rising temperatures in recent decades.
‘Sports on a Frozen River’ by Aert van der Neer, C1660 (Metropolitan Museum of Art, New York). Northern Europe experienced freezing winters during the Maunder Minimum
According to models which simulate conditions from 2050 to 2099, a possible “grand solar minimum” would cool the planet by just 0.1C. Parts of northern Europe would feel a larger cooling effect of between -0.4 and -0.8C.
The planet could overheat by as much as 5C on pre-industrial levels in the same period, if greenhouse gas emissions follow current trends.
“The 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-man change,” said Sarah Ineson, a scientist at Britain’s Met Office and lead author in a statement.
“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.”
Incidence of sunspots fell dramatically in the 17th and 18th centuries (Photo: NASA)
Another finding was a drop in ultraviolet rays could leading to a “sizeable fraction” of cooling at lower atmospheric concentrations of emissions.
Amanda Maycock, a scientist at the University of Cambridge and National Centre for Atmospheric Science, said: “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.”