Update – 20th January: The Daily Mail has written up the story this weekend, covering some very similar ground. The main thing to remember is that scientists think the effect of lower solar activitity will be regional rather than global.

Colder winters in Europe aren’t inconsistent with a world that’s warming up on the whole. See this guest blog post from Professor Mike Lockwood for a clear explanation of what scientists think is going on.

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Last night, BBC’s Newsnight delved into a question that seems to fascinate the media. A six-minute report entitled “What’s happening to our sun?” asked how much a drop in solar activity could affect the climate here on earth. The answer from scientists is very little.

We’ve written about the sun’s effect on climate  many times. We recently had a guest blog by Professor Mike Lockwood – solar scientist at the University of Reading – about the many myths, misconceptions and misnomers about the topic.

It’s well worth a read. But here’s a summary of the main points.

A declining sun

Back in the 17th century, the sun went through a period of prolonged low activity, called the Maunder Minimum. This coincided with the beginning of what’s become known as the Little Ice Age, when parts of the northern hemisphere cooled by as much as two degrees Celsius. (Incidentally, read Mike Lockwood’s blog for an explanation of why it wasn’t a ‘Little Ice Age” at all.)

Scientists think the next low point in solar activity could be low enough to rival the Maunder Minimum, which often leads to the question of whether we could see a return to freezing conditions. In the Newsnight report, presenter Rebecca Morelle asks:

“Does a decline in solar activity mean plunging temperatures for decades to come?”

Consequences for Europe, but a small effect globally

But the link between declining solar activity and freezing temperatures is far from simple.

Morelle talks to Lockwood, who explains that a pronounced low in solar activity could cause a drop in temperature across Europe. It does this by affecting the position of the jet stream, a rapidly moving ribbon of air high up in the atmosphere that controls weather patterns in the northern hemisphere.

But Lockwood points out temperature changes in the northern hemisphere are only a small piece of the global picture, warning:

“One has to make a very clear distinction between regional climate and global climate. If we get a cold winter in Europe because of these blocking events, its warmer in Greenland for example. So the average is almost no change. It’s a redistribution of temperature around the North Atlantic.”

But despite Lockwood’s point that global temperature is unlikely to be affected much, Morelle follows up by asking:

“The relationship between solar activity and weather on earth is complicated, but if solar activity continues to fall, could the temperature on earth as a whole get cooler? Could there be implications for global warming?”

To be fair, the report goes on to answer this question – arriving at the conclusion that the earth is likely to continue to warm. But raising the notion that earth could “as a whole get colder” is a little too reminiscent of media declarations from time to time that “Britain faces a new mini-Ice Age”.

Global warming outcompetes solar effect

In the BBC report, Lucy Green from the Mullard Space science Laboratory in the South Downs explains why the context is very different now than in the 17th century. She says:

“The word we live in today is very different from the world that was inhabited during the Maunder Minimum. We’ve had human activity, we’ve had the industrial revolution, all kinds of gases being pumped into the atmosphere. So on the one hand you’ve got perhaps a cooling sun, but on the other you have human activity that can counter that”.

But while Green says it’s “quite difficult” to know how the competing effects of a cooling sun and global warming will interact, other scientists are much clearer on this question. Lockwood, for example, says:

“[My research with the Met Office’s Hadley Centre shows] the likely reduction in warming by 2100 would be between 0.06 and 0.1 degrees Celsius, a very small fraction of the warming we’re due to experience as a result of human activity”.

In other words, the slight drop in global temperature coming from a drop in solar activity may be just about detectable if we weren’t having a much bigger impact through carbon dioxide emissions. While the BBC could perhaps have been clearer on that point, Morelle concludes:

“So even if the planet as a whole continues to warm, the future for northern Europe could be cold and frozen winters for decades to come.”

So the report strikes the right note at the end, highlighting that colder winters in Europe aren’t inconsistent with a world that’s warming up on the whole. Let’s hope everyone stayed tuned in till the end.