I believe climate change is happening. When you look at the glacial and Arctic melts and the global temperature trend, it's pretty hard to argue with climate change as fact.
I do try, however, to keep an open mind as to its cause. I'm 90% convinced that greenhouse gases are the culprit, but I attempt reserve some openness as to other influences. After all, we can barely predict the weather two days out, so climate change modeling seems to be a bit beyond our capabilities.
So when I read an article last summer in Discover Magazine about cosmic rays being a contributor to the warming trend, I paid close attention. Henrik Svensmark's hypothesis is that sun cycles impact cloud formation, and cloud formation has a pretty significant impact on the temperature. If the sun is generating more cosmic rays than usual, less clouds may form, and the planet may get cooler.
Even recent geologic findings have corroborated the significance of clouds influencing temperature, demonstrating that when clouds are absent, the world has entered periods of "super-greenhouse" in the Cetaceous and Eocene periods.
Scientists can definitively demonstrate that as the world has heated up, there have been less clouds, but aren't sure whether it is cause or effect. Could it be sun activity, or is it just the greenhouse effect acting as predicted?
A new study released from Durham University and the University of Lancaster may have the answer. Using cloud coverage data from satellites, they attempted to do a basic correlation with sun activity data (sun spot indices and muon particle observations) over the last 20 years. They did not find much to back up Mr. Svensmark's hypothesis.
According to the study, current data claiming a connection between cosmic rays and clouds completely avoids high-altitude clouds. This is opposite of what you would expect, since cosmic rays would probably be intercepted higher in the atmosphere, causing more high-altitude clouds, not producing lots of low-level cloud cover.
Given the way Earth's magnetic field works, cosmic rays are particularly channeled towards our poles, which is why you see amazing Northern and Southern lights there as the particles dance through the atmosphere. In theory, the poles are more susceptible to cosmic ray increases and thus would receive the biggest delta in cloud activity. Nope. In fact, the scientists found the opposite.
"...no corroboration of the claim of a causal
connection between the changes in ionization and low cloud
cover...could be found in this investigation...We find that, averaged
over the whole Earth, less than 23% of the dip comes from solar
modulation of the cosmic ray intensity, at the 95% confidence level.
This implies that, if the dip represents a real correlation, more than
77% of it is caused by a source other than ionization."
Translating the science speak, the data indicates there is no
evidence for strong correlation, but does not completely rule out small
influences. Overall, 77% of cloud activity seems to be controlled by
something other than cosmic rays.
"There is no connection between global warming and cosmic rays. That's
because there's no trend in cosmic rays. It's completely bogus,"
remarked Dr. Gavin A. Schmidt, a NASA researcher and contributor.
I continue to keep an open mind, but my personal skepticism about cosmic ray theory has reached new heights.