Cosmic Connection

Astrophysicist Nir Shariv, one of Israel's top young scientists, describes the logic that led him -- and most everyone else -- to conclude that SUVs, coal plants and other things man-made cause global warming.

Step One: Scientists for decades have postulated that increases in carbon dioxide and other gases could lead to a greenhouse effect.

Step Two: As if on cue, the temperature rose over the course of the 20th century while greenhouse gases proliferated due to human activities.

Step Three: No other mechanism explains the warming. Without another candidate, greenhouses gases necessarily became the cause.

However after carefully looking at the evidence Nir no longer believes that CO2 is to blame for current warming.

Nir believes that cosmic rays provide a more plausible explanation. In another study, directly relevant to today's climate controversy, Dr. Shaviv reconstructed the temperature on Earth over the past 550 million years to find that cosmic ray flux variations explain more than two-thirds of Earth's temperature variance, making it the most dominant climate driver over geological time scales. The study also found that an upper limit can be placed on the relative role of CO2 as a climate driver, meaning that a large fraction of the global warming witnessed over the past century could not be due to CO2 -- instead it is attributable to the increased solar activity.

CO2 does play a role in climate, Dr. Shaviv believes, but a secondary role, one too small to preoccupy policymakers. Yet Dr. Shaviv also believes fossil fuels should be controlled, not because of their adverse affects on climate but to curb pollution.

Cosmic ray theory is gaining some traction since Danish National Space Center experimentally proved that cosmic rays create cloud nuclei and therefore influence the climate by altering the number of low altitude clouds (current climate models cannot model cloud behavior). The theory is taken seriously enough for CERN to conduct their own experiment similar to Danish. The results will be out in the first part of the year.