The mud at the bottom of B.C. fjords reveals that solar output drives climate change – and that we should prepare now for dangerous global cooling
R. TIMOTHY PATTERSON, professor and director of the Geoscience Centre, Carleton University
Published: Wednesday, June 20, 2007
Our finding of a direct correlation between variations in the brightness of the sun and earthly climate indicators (called “proxies”) is not unique. Hundreds of other studies, using proxies from tree rings in Russia’s Kola Peninsula to water levels of the Nile, show exactly the same thing: The sun appears to drive climate change.
However, there was a problem. Despite this clear and repeated correlation, the measured variations in incoming solar energy were, on their own, not sufficient to cause the climate changes we have observed in our proxies. In addition, even though the sun is brighter now than at any time in the past 8,000 years, the increase in direct solar input is not calculated to be sufficient to cause the past century’s modest warming on its own. There had to be an amplifier of some sort for the sun to be a primary driver of climate change.
Indeed, that is precisely what has been discovered. In a series of groundbreaking scientific papers starting in 2002, Veizer, Shaviv, Carslaw, and most recently Svensmark et al., have collectively 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 generated during these “high sun” periods blocks many of the cosmic rays from entering our atmosphere. Cloud cover decreases and the Earth warms still more.
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. By comparison, CO2 variations show little correlation with our planet’s climate on long, medium and even short time scales.
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