Do cosmic rays hold sway over climate?
THE controversial idea that cosmic rays could be driving global warming by influencing cloud cover will get a boost at a conference next week. But some scientists dismiss the idea and are worried that it will detract from efforts to curb rising levels of greenhouse gases. At issue is whether cosmic rays, the high-energy particles spat out by exploding stars elsewhere in the galaxy, can affect the temperature on Earth. The suggestion is that cosmic rays crashing into the atmosphere ionise the molecules they collide with, triggering cloud formation. If the flux of cosmic rays drops, fewer clouds will form and the planet will warm up. No one yet understands the mechanism, which was first described in the late 1990s. But what makes it controversial is that climate models used to predict the consequences of rising levels of greenhouse gases don’t allow for the effect, and may be inaccurate. Some …
