READ THE SUNSPOTS
June 22, 2007
Climate stability has never been a feature of planet Earth. Ten thousand years ago, temperatures rose as much as 6 degrees Celsius in a decade -- 100 times faster than the past century's 0.6C warming, says Timothy Patterson, professor and director of the Ottowa-Carleton Geoscience Centre at Carleton University.
Given this variability throughout time, factors other than man-made CO2 emissions need to be considered as the driving force behind climate change. According to Patterson, one likely culprit is the sun:
- Many scientific papers have demonstrated that as the output of the sun varies, and with it, our star's protective solar wind, varying amounts of galactic cosmic rays from deep space are able to enter our solar system and penetrate the Earth's atmosphere.
- These cosmic rays enhance cloud formation which, overall, has a cooling effect on the planet.
- When the sun's energy output is greater, not only does the Earth warm slightly due to direct solar heating, but the stronger solar wind blocks many of the cosmic rays from entering our atmosphere; cloud cover decreases and the Earth warms still more.
Likewise, the opposite occurs when the sun is less bright:
- More cosmic rays are able to get through to Earth's atmosphere, more clouds form, and the planet cools more than would otherwise be the case due to direct solar effects alone.
- This is precisely what happened from the middle of the 17th century into the early 18th century, when the solar energy input to our atmosphere, as indicated by the number of sunspots, was at a minimum and the planet was stuck in the Little Ice Age.
These new findings suggest that changes in the output of the sun caused the most recent climate change, says Patterson. By comparison, CO2 variations show little correlation with our planet's climate on long, medium and even short time scales.
Source: Timothy Patterson, "Read the Sunspots," Financial Post, June 20, 2007.
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