Will Fewer Sunspots Mitigate Global Warming?

By David L. Brown

The reality of global warming is becoming more and more widely accepted, and there is evidence of a desire to find an easy way out of the dilemma. One example is provided by an article in the current issue of New Scientist magazine titled “Saved By The Sun” (16-22 Sept. 2006, pgs. 32-36). The article discusses the possibility that the Sun is about to enter a sunspot minimum, something that happens about every 200 years, and describes the likelihood that this could lower global heating. As you will see below, I believe the promise of the article’s title is overly optimistic, but before we get to that here is an excerpt from the article to give you the background on this theory:

Global average temperatures have risen by about 0.6 °C in the past century, and until recently almost all of this has been put down to human activity. But that may not be the only factor at work. A growing number of scientists believe that there are clear links between the sun’s activity and the temperature on Earth. While solar magnetic activity cannot explain away global warming completely, it does seem to have a significant impact. “A couple of years ago, I would not have said that there was any evidence for solar activity driving temperatures on Earth,” says Paula Reimer, a palaeoclimate expert at Queen’s University, Belfast, in the UK. “Now I think there is fairly convincing evidence.”

What has won round Reimer and others is evidence linking climate to sunspots. These blemishes on the sun’s surface appear and fade over days, weeks or months, depending on their size. More than a mere curiosity, they are windows on the sun’s mood. They are created by contortions in the sun’s magnetic field and their appearance foretells massive solar eruptions that fling billions of tonnes of gas into space. Fewer sunspots pop up when the sun is calm, and historically these periods have coincided with mini ice ages.

The article goes on to explain that the sunspot minima may help usher in cold spells by radically reducing the amount of ultraviolet radiation reaching the Earth. It makes the point that a 21st century “crash” in sunspot activity could help relieve the human-induced warming that is beginning to build up momentum.

While it is true that periods such as the so-called Little Ice Age in the last half of the 17th century brought extreme cold to Europe and the North Atlantic, it appears that the effect was localized and was due to changes in climate patterns rather than a big overall reduction in global temperatures. Evidence from tree rings and ice cores indicates that other parts of the world may not have even noticed these dips in temperature that were so strong in the Northern Hemisphere. According to the article, a future dip in solar activity might only bring a cooling of about 0.2 degrees C., and the effect of changes in the Sun’s output during the last century could only explain about 30 percent of the observed warming. Human induced warming resulting from emissions of greehhouse gas remains the biggest problem we face.

A period of reduced solar activity might be helpful as we enter an unknown future in which we may already have reached tipping points in the climate which will lead to more and more rapid warming. But in my opinion there might be reason to believe that the effect might not be very helpful at all. When I read about an effect such as this, I tend to start to connect the dots to other known facts or possibilities. Although the New Scientist article did not mention it, if its statement that the effect could be regional is true, that could actually set the stage for an even greater calamity in Europe and other Northern Hemisphere regions.

Why do I say that? Because I have connected the dots to one possible result of warming in the far north. The on-going thawing of the Arctic ice cover already is threatening the Atlantic thermohaline conveyor, the massive stream of warm surface water that draws heat up from the tropics to warm western Europe. As the Arctic Ocean becomes warmer and less salty, it is feared that the system might be disrupted and could even reverse. If a new Little Ice Age resulting from reduced Solar activity were to begin at about the same time that the Atlantic conveyor were to stop or reverse, the result could be even more catastrophic cooling around the North Atlantic basin. That could plunge places like the British Isles, Scandinavia, and even much of Germany and France into a deep freeze that would make those nations uninhabitable. It could launch a new era of glaciation in those areas even as other parts of the globe become even warmer.

Yes, odd as it might seem, global warming does not take place as a gradual, overall rise in temperatures in all locations. Although the world average temperature has risen by only about 0.6 degrees C. in the past century, in the Arctic the increase has been far higher. In Alaska the temperature has already risen by about 7 degrees C. and a massive thaw is under way not only in the Arctic Ocean but in once permanently frozen regions in Siberia and the upper reaches of North America. Just as the cooling effects of a solar minimum might have regional effects by initiating climate change, so does global warming. These two factors might reinforce each other to create a pile-on effect that would throw Europe back into a new Ice Age. Not a Little Ice Age, but the real thing.

As nice as it would be to think so, unfortunately, there are no easy answers to the climate change that is now under way. The authors of the New Scientist article point to the danger of taking comfort from the possibility that natural effects could help save us from the consequences. The author addresses this, quoting solar physicist turned computer programmer Leif Svalgaard, from Stanford University:

There is a dangerous flip side to this coin. If global warming does slow down or partially reverse with a sunspot crash, industrial polluters and reluctant nations could use it as a justification for turning their backs on pollution controls altogether, making matters worse in the long run. There is no room for complacency, Svalgaard warns: “If the Earth does cool during the next sunspot crash and we do nothing, when the sun’s magnetic activity returns, global warming will return with a vengeance.”

It is my opinion that humankind will have little choice in the matter. If we do not reduce industrial pollution of the atmosphere by greenhouse gases through heroic efforts, it will occur as the natural result of a collapse of civilization. It is encouraging to see growing awareness of the problem, but there are many great dangers and challenges ahead.

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