By Bradley J Fikes
Today, blogs around the world are being urged to dramatize the dangers of global warming. For all the politicization of the subject, global warming is supposed to be grounded in science. So I’m going to highlight some interesting science on how the earth may warm. It’s from a scientific team led by Henrik Svensmark, director of the Center for Sun-Climate Research at the Danish Space Research Institute.
Svenskmark’s hypothesis is that cosmic rays play an important role in cloud formation, and that high levels of solar activity interfere with cosmic rays reaching Earth. Cosmic rays seed the formation of nuclei that collect water, forming clouds. When the sun is active, it emits radiation that blocks or deflects cosmic rays, reducing the cloud-forming nuclei.
So when the sun is active, there is less cloud cover, hence, more warming.
Svenskmark has published this hypothesis in scientific journals. But instead of being welcomed as the bringer of a novel concept, he has been met with scorn by scientists who think global warming by greenhouse gases is settled science.
This spring, scientists led by Peter Adams, a professor of civil and environmental engineering at Carnegie Mellon University, tried to drive a stake through the cosmic ray hypothesis. In a paper published in the journal Geophysical Research Letters, “Can cosmic rays affect cloud condensation nuclei by altering new particle formation rates?” the team reported results of a computer model of cosmic ray interaction with clouds.
The computer model showed that the cosmic ray effect was 100 times too small to alter the climate, according to a Carnegie Mellon press release on the study. The release also called the effect a “troubling hypothesis,” now proven to be a “myth” that should be “laid to rest.”
Of course, one can prove anything with a computer model. And it’s really not surprising that a scientist who is also an activist supporting global warming theory, as is Adams, would find the cosmic ray hypothesis “troubling.” It threatens his scientific reputation. Scientists are idealized as just looking for the data, without letting their biases get in the way, but that stereotype is no more true than that of journalists being unbiased.
So just as journalism is helped when people of different views do the reporting, science is helped when people advance a variety of different ideas. If one side controls the discussion, groupthink and enforced conformity take over.
And Svensmark and colleagues have not backed down. They produced another paper giving more evidence for the cosmic ray hypothesis, also in Geophysical Research Letters: “Cosmic ray decreases affect atmospheric aerosols and clouds.”
Svenskmark’s team measured the level of cloud cover after especially large, sudden decreases in cosmic rays, called Forbush decreases. The team concentrated on low-level clouds, which previous research indicated would be most affected by cosmic ray levels.
For the five strongest Forbush decreases, from 2001 to 2005, the team found a 7 percent decrease in the liquid water content of clouds. The vanishing water remained in the air as water vapor, but unlike liquid water, it doesn’t block sunlight. And satellite measurements of the area of cloud cover found a 5 percent decrease.
Such a drop in cloud cover, Svensmark says, is equal to all the global warming on earth during the 20th century.
So who is right? I don’t pretend to know. We’ll need far more research and a healthy scientific debate to figure out what is really going on — warming through cosmic rays, greenhouse gases, both, or neither.
But I do know when people use political pressure to advance their viewpoint, it’s more like religion than science. A good scientist should be delighted to learn of contrary evidence to a generally accepted theory, because that’s an opportunity to correct an error. To call the evidence “troubling” is a political reaction, not a scientific one.
In short, just as you should be wary of agenda-driven journalism, beware of agenda-driven science. Keep your mind open to new evidence, and value independence over peer pressure to intellectually conform.
As with all I write here, this is my viewpoint, and not necessarily that of my employer, the North County Times.