Could the sun be the cause of global warming?
As a meteorologist, Im often asked about climate change. And while Ive explained a lot of the basic concepts in previous Moments of Science, from how greenhouse gases heat our planet to the differences between weather & climate, theres still a lot of questions about this heated topic that I havent covered just yet. Graph of global temperature change (red) and solar energy (yellow) over time. Credit: NOAA  While the suns energy output can influence our climate, there has not been a significant change in the amount of solar radiation reaching Earth since satellites have been measuring it in 1978. In that same time frame, weve seen global temperatures skyrocket. Theres another piece of data that goes against this hypothesis. If the sun was responsible for global warming, all levels of our atmosphere would be warmer as the suns rays pass through them. But that is not the case as our troposphere is getting warmer, while the layer above us, the stratosphere, is cooling- indicative of the buildup of greenhouse gases trapping heat at the surface. Atmospheric CO2 concentrations measured in parts per million. Credit: NOAA  This usually leads to more questions, often asking what about blank?  The bottom line is that no other known climate influences have changed enough to account for the observed warming trend this century. Unfortunately, the evidence points to us and our activities. Global CO2 levels today are higher than any point in at least the past 800,000 years, now measuring 420 parts per million in a sample of air. I understand that time frame going back hundreds of thousands of years has some of you doubtful about the credibility of that statement. But there is a high resolution record of our atmospheric gas concentrations that dates back nearly a million years. Ice cores, ocean sediments, tree rings, and other climate proxies allow scientists to reconstruct our climate past to better predict our climates future. Next week Ill explain more about these methods and highlight the different ways climatologists have pieced together our past weather here in the Palmetto state. Storm Team 2 Meteorologist David Dickson