Sunspots, CO2, and their correlation with climate change

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Sunspots

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The argument over humanity's contribution to climate change is heating up in America and around the world as legislation meanders its way through the Senate and governments prepare for the UNFCCC meeting later this year. 

On one side, climate and environmental activists cite examples of high levels of CO2 as the primary driver of the greenhouse effect.  The contrary argument states that warming and cooling trends on Earth are driven predominantly by cycles of solar output originating with the sun. 

If the former activists are correct, then humanity can take legitimate steps to reduce the factors contributing to climate change.  If the latter argument is on point, then taking measures to reduce emissions is simply an economic experiment.

The current bill in Congress and the agenda being seriously discussed by the governments of the world ahead of the Copenhagen conference later this year attempts to set a course to significantly lower CO2 emissions over the coming decades.  This strategy takes into account data from respected scientists that point to a correlation between CO2 levels and temperature rises over the past 800,000 years.

Similarly, advocates for the contrary argument of solar variation causing climate change rely on data that points to correlations between solar activity and changes in temperature.

In both cases, correlations exist; but as the cartoon above draws the distinction, in mathematical statistical scenarios, "Correlation doesn't imply causation, but it does waggle its eyebrows suggestively and gesture furtively while mouthing 'look over there'".  (Columbia)

Both the CO2 and solar variation correlations are suggesting that we look more into these phenomena.  One we can do something about; the other we can not.  The question being asked now in the debate is whether or not doing something about climate change will affect the outcome in ways that we desire.  Should the governments of the world unite to reduce greenhouse gas emissions, or should the governments of the world allow for the continuance of business as usual?  Seemingly, both are strategies for dealing with climate change.

Advocates of the sunspot theory argue that not enough attention has been paid to solar forcing as the driver of climate change.  "It is found that current climate models underestimate the observed climate response to solar forcing over the twentieth century as a whole, indicating that the climate system has a greater sensitivity to solar forcing than do models.  The results from this research show that increases in solar irradiance are likely to have had a greater in?uence on global-mean temperatures in the ?rst half of the twentieth century than the combined effects of changes in anthropogenic forcings"; but the paper goes on to also state, "Nevertheless the results con?rm previous analyses showing that greenhouse gas increases explain most of the global warming observed in the second half of the twentieth century". (Peter Stott)

Not to be confused with P. Stott (above) from the Hadley Centre for Climate Prediction and Research in the UK, Phillip Stott, professor of biogeography at the University of London, does not address the idea of solar variation directly, but tackles the larger issue of climate change.  "The global warming myth harks back to a lost Golden Age of climate stability, or, to employ a more modern term, climate 'sustainability'.  Sadly, the idea of a sustainable climate is an oxymoron.  The fact that we have rediscovered climate change at the turn of the Millennium tells us more about ourselves, and about our devices and desires, than about climate.  Opponents of global warming are often snidely referred to as 'climate change deniers'; precisely the opposite is true.  Those who question the myth of global warming are passionate believers in climate change; it is the global warmers who deny that climate change is the norm."

Before human intervention, the climate on Earth changed regularly.  The governments of the world have a responsibility to ensure economic prosperity to their citizens; they were not entrusted with controling the climate.  Even as evidence points to greenhouse gases as a contributor to climate change, will it be possible to change the outcome by manipulating only one of the variables?  That question is often taken on by advocates of the sunspot correlation.

Peter Stott presented his data on solar variation to the UNFCCC bodies in 2007.  Philip Stott, a skilled debater and not a climate scientist, used his knowledge of climate change in an Oxford-style debate aired on NPR. 

Both Stotts were successful in their endeavors, one proving that sunspots had an effect on climate change and the other proving that sunspots had an effect on climate change.  The former argued that human actions were adding to the effects of solar variation on the Earth.  The latter argued that climate varies on earth naturally, so to try to mitigate human impacts is a fruitless endeavor; the latter was subsequently accused of using unscientific measures and misleading strategies (ClimateProgress) to influence public opinion.

Effects of solar variations on the Earth are still largely undefined.  Many of the hypotheses surrounding solar variation are significantly less developed than the science surrounding anthropogenic effects.  "Changes in the Sun's brightness over the past millennium have had only a small effect on Earth's climate, according to a review of existing results and new calculations performed by researchers in the United States, Switzerland, and Germany."  There is a correlation between sun cycles and climate change, but  "Our results imply that, over the past century, climate change due to human influences must far outweigh the effects of changes in the Sun's brightness." (UCAR)

The climate has been and still is a complex system with multiple input variables and output effects; the interplay responds to forces from the sun, the oceans, the environment, and yes, human interactions with it.  The idea that the sun is the sole determining factor of climate change on Earth is as preposterous as the claim that CO2 is the driving factor.  Both contribute to the dynamic process.

The problem with advocates for the sunspot hypothesis is that the idea lends itself to a passive approach to dealing with the effects of climate change.  BBC stated in a piece called Sunspots reaching 1000-year high that "this latest analysis shows that the Sun has had a considerable indirect influence on the global climate in the past, causing the Earth to warm or chill, and that mankind is amplifying the Sun's latest attempt to warm the Earth".

This gets at the heart of the problem of inaction.  Modern human society is escalating the natural effects of the process of climate change.  To take measures to reduce the level of greenhouse gases that are aggravating the situation is the responsible thing to do; it is what governments around the world were created to do, particularly Democracies entrusted with protecting the people under its care.  To not act would be considered dereliction of duty.

We know CO2 and solar variations affect the climate on Earth.  We can certainly change the structure of our global energy markets to change the level of CO2 humanity is emitting; we can't change the solar output from the sun.  Will lowering the level of greenhouse gas emissions from human society be enough to slow down climate change to a more manageable pace?

For more info:  Sunspots and weather cycles belie global-warming hysteria, Climate Change Fraud. Global warming could cool N. America in a few decades; National Geographic.