Originally published September 2013.
Has solar output been causing global warming, and not human carbon dioxide emissions? Sunspot numbers in 2013 have been well below average for this point in the cycle. If we are now heading into a grand minimum of solar activity, will that reverse the changes in climate we have been experiencing over the past several decades? That would be great! The average temperature would start going down and we would go back to normal patterns of weather, like our grandparents lived with. Unfortunately, you can’t change the recorded facts and the projections of climate models just by saying so. Climate Crock of the Week did a good job on this:
Earth continues to grow warmer. Because of cyclical changes in the patterns of ocean currents, much of the extra heat has been absorbed into the sea in the past decade. The ocean retains less heat from the atmosphere and solar radiation in El Niño years, and more when La Niña prevails. That’s why it’s important to pay more attention to the long-range average temperatures. Brad Plumer has some nice references in his article at the Washington Post.
Sunspot numbers are indeed indicators of the relative intensity of solar output. Solar irradiance is, of course, taken into account by climate scientists as they crunch their data. Unfortunately for us, that variance in the sun’s strength will not be enough to override the warming caused by human activities, even if sunspots were to disappear entirely.