Once again, the Sun’s influence on the current state of our climate has been called into question, with the link between incoming cosmic rays and global warming being refuted. Meanwhile, Solar Cycle 24 has got off to a grindingly slow start. Where have all the sunspots gone?
Back in June 2007, I wrote about some Canadian research that suggested there’s a link to be found between the strength of incoming cosmic rays from deep space and global temperatures. R. Timothy Patterson is professor and director of the Ottawa-Carleton Geoscience Centre, Department of Earth Sciences, Carleton University. His research into mud deposits at the bottom of British Columbia’s fjords found strong correlations between two sets of data: the more incoming cosmic rays, the greater the numbers of scales from dead fish which had perished in temperatures much cooler than they could stand.
The cloud-forming capacity of incoming cosmic rays is determined by the amount of protection Earth is given by the Sun’s solar activity: when the Sun is in a highly active phase (indicated by a high number of sunspots), fewer cosmic rays from deep space penetrate our atmosphere because they’re deflected by the Sun’s intense solar wind. Fewer clouds are formed. Less cloud cover means more heat from the Sun is absorbed at the Earth’s surface, and the planet warms up. When the Sun is in a quiet phase (as it is right now), more cosmic rays penetrate the atmosphere, encouraging the formation of more clouds which reflect a greater amount of the Sun’s heat back into space. The planet then cools down. Patterson contends that with the Sun due to undergo a particularly quiet Schwabe Cycle (the formal name for the 11-year Solar Cycles, indicated by sunspot activity) by 2020, the Earth is heading for another period of sustained global cooling, such as was endured during the Middle Ages (the Little Ice Age).
I followed this up in July 2007 with a post detailing more research about the Sun’s influence on Earth — specifically, how data analysis carried out by the UK’s Rutherford-Appleton Laboratory seemed to rule out any cosmic ray influence on the recent trend of rising global temperatures. The laboratory undertook the research in an effort to clarify cosmic ray research published by Henrik Svensmark and Eigil Friis-Christensen of the Danish National Space Center — work included in a controversial TV documentary called The Great Global Warming Swindle and which suggested that global warming has little to do with human activity but is much more influenced by natural phenomena.
The laboratory’s findings reinforced the belief that the warming of the last 20 to 40 years cannot have been caused by solar activity, according to Dr Piers Forster from Leeds University, a leading contributor to the Intergovernmental Panel on Climate Change (IPCC) 2007 assessment of climate science.
Now comes further research, from the University of Lancaster and reported by the BBC, which adds fuel to the fire. The research team used three different ways to search for a correlation and could find no significant link between cosmic rays and cloudiness in the last 20 years.
They looked for periods in time and for places on Earth with documented weak or strong cosmic ray arrivals to see if the cloudiness observed in those locations or at those times was affected. “For example: sometimes the Sun ‘burps’ — it throws out a huge burst of charged particles,” the university’s Terry Sloane explained. “So we looked to see whether cloud cover increased after one of these bursts of rays from the Sun; we saw nothing.” Over the course of one of the Sun’s natural 11-year cycles, there was a weak correlation between cosmic ray intensity and cloud cover — but cosmic ray variability could at the very most explain only a quarter of the changes in cloudiness. And for the following cycle, no correlation was found.
Not surprisingly, Dr Svensmark was unimpressed by the findings, saying that “Terry Sloan has simply failed to understand how cosmic rays work on clouds. He predicts much bigger effects than we would do, as between the equator and the poles, and after solar eruptions; then, because he doesn’t see those big effects, he says our story is wrong, when in fact we have plenty of evidence to support it.”
Meanwhile, Solar Cycle 24, which began when the first high latitude, reversed polarity sunspot appeared on 4th January 2008, has now — at long last — produced its second sunspot (as shown in the animation, from spaceweather.com). This began emerging on 12th April, some three months after the previous Solar Cycle 24 sunspot. It’s not a particularly impressive spot — it hasn’t even been given an official number yet. In the months ahead, says SpaceWeather.com, we can expect more new-cycle spots as solar activity slowly climbs from its current low ebb and ascends toward the next Solar Maximum expected in 2011-12.
I can imagine a collective sigh of relief from the astronomers who first logged the appearance of this elusive second sunspot. The three months between this sunspot and the previous one feels like a long time to me, though as yet I’ve not been able to uncover any comparable detailed data from previous beginnings of Solar Cycles so I can ascertain for myself whether this is actually the case.
Maybe, in solar activity terms, three months between the inaugural sunspots of a new cycle is normal — but conversely, perhaps it suggests a slower than usual start to the cycle, which in turn might mean the height of the activity, due around 2012, will be less intense than forecast. And if this were to be followed by a really quiet Solar Cycle 25, as Patterson seems to be suggesting, then maybe the cumulative effect of this decrease in solar activity will have a significant cooling effect here on Earth.
Such a protracted period of decreased solar activity would allow a greater number of cosmic rays to interact with the atmosphere over a longer period of time than is the norm. While the cooling triggered by cosmic ray-generated clouds may not, in isolation, be sufficient to offset global warming caused by ever-increasing volumes of atmospheric greenhouse gases, other factors — such as Gulf Stream cessation and the dramatic disruption of associated weather patterns — may yet come into play to create a combination of climatic conditions that, when acting holistically, could have chilling consequences.
Read my Climate Change posts in chronological order by using the Climate Change Log.