Solar activity and new “little” ice age, and another interpretation

The Lomonosov State University Moscow has published a press release that presents evidence for the possibility of a small “little” ice age developing in about fifteen to twenty years. The evidence is that the sun undergoes cycles in activity indicated by the number of observed sun spots (50 per year during the previous little ice age lasting from 1645 to  1700, and 40 – 50 000 during the warmer period after it), and that we are approaching a point when activity should decrease.

 

“In 17th century, though, there was a prolonged reduction in solar activity called the Maunder minimum, which lasted roughly from 1645 to 1700. During this period, there were only about 50 sunspots instead of the usual 40-50 thousand sunspots. Analysis of solar radiation showed that its maxima and minima almost coincide with the maxima and minima in the number of spots.”

“If the similar reduction will be observed during the upcoming Maunder minimum this can lead to the similar cooling of the Earth atmosphere. According to Dr Helen Popova, if the existing theories about the impact of solar activity on the climate are true, then this minimum will lead to a significant cooling, similar to the one occurred during the Maunder minimum.

However, only the time will show soon enough (within the next 5-15 years) if this will happen.”

 

Full article here:

http://astronomynow.com/2015/07/17/diminishing-solar-activity-may-bring-new-ice-age-by-2030/

 

I have asked Professor Michael Box, a renowned climate physicist from the University of NSW, Sydney, to comment on this post and he has given me permission to add his comments here.

Klaus,
Yes, it is causing quite a stir, isn’t it? Let me see how much light I can shed.

The analysis techniques used to underpin the prediction of very low sunspot numbers (principal component analysis) is well known and ‘valid’ as to what it does. Using it to project into the future is somewhat less valid, as other factors which have not shown up in the past data may be waiting in the wings. I guess I would rate the chances of very low sunspot numbers in the 2030s as less than 50-50, but certainly not at, or close to, zero.
So that brings us to the more important issue of the impacts. The Little Ice Age (so-called) is certainly ‘real’, although many questions remain.
When did it begin? I’ve seen dates of anywhere from 1300 to 1450 – both well before the start of the Maunder Minimum in 1645.
When did it end? Again I’ve seen dates as late as 1850 (well after the end of the MM in 1715), which might well imply that the only reason it did end is the onset of global warming!
Was it global, or regional? There is plenty of evidence from Europe and some from North America. I’ve seen a suggestion of some evidence from New Zealand. However there do seem to be many questions around the uniformity of the cooling.
So that brings us to the really key question of the causes/drivers. Solar activity is certainly one possibility, although as I’ve indicated the MM certainly couldn’t have started it. It may have made things just a little bit cooler – say 0.2 C – but it wasn’t the cause! Other suggestions have been a slowing of the Gulf Stream (it has slowed significantly in the past. ~11,000 years ago); volcanic activity (a couple of major eruptions followed by some feedbacks); and ‘orbital forcing’. We know that changes in the Earth’s orbit are the drivers of the glacial-interglacial cycle (something one of the authors of the paper in question is clearly ignorant of!), and these drivers don’t stop and start, but are on-going. We probably are heading ever so slowly for the next glacial.
Like most scientists who have made ‘meaningful’ comments, my view is that, if it does happen, it will reduce global warming by ~0.1 C – or delay it by ~10 years. And that delay would only be temporary, and temperature would zoom ahead in the years that followed.

 

Interesting to compare this critical account with a story published in news.com.au (a Murdoch site), in which the ‘coming ice’ age is more or less presented as a fact (“Earth heading for ‘mini ice age’ within 15 years’) and rounded up with drawing attention to the present cold front affecting SE Australia:

“Tropical-style thunderstorms, accompanied by heavy snowfalls, roared through the Blue Mountains, west of Sydney, and towns as far as Orange on Saturday night.”

Full story here:

http://www.news.com.au/technology/environment/earth-heading-for-mini-ice-age-within-15-years/story-e6frflp0-1227439329592

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