"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.
Dr. Shariv, a prolific researcher who has made a name for himself assessing the movements of two-billion-year-old meteorites, no longer accepts this logic, or subscribes to these views.
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."
- from the article.