One question that folks who are skeptical about global warming have is whether or not natural solar activity could be affecting the rise in temperature seen in recent decades. A number of research programs have attempted to determine if there is a relationship between sunspots or cosmic radiation and Earth’s temperature. This recent article from the Climate News Network describes some of this research and confirms that observed changes in solar radiation cannot explain the Earth’s warming.
Scientists do know that the long-term variation in solar radiation received by the earth that is caused by changes in the Earth’s orbit around the sun is the main driver of ice ages, but this is on a substantially longer time scale than the recent temperature changes in the Earth’s climate system and so cannot explain the warmer temperatures. In fact, if that were the only factor acting on Earth’s climate, then we would be gradually getting cooler on our way to the next ice age in 10,000 years or so.
