JoNova

A science presenter, writer, speaker & former TV host; author of The Skeptic's Handbook (over 200,000 copies distributed & available in 15 languages).


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Think it has been debunked? See here.

The Skeptics Handbook II

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If carbon didn’t warm us, what did?

Svensmarks Cosmic Ray Theory. TOP: If the sun’s magnetic field is weak it allows more cosmic rays, which may seed more clouds on Earth. BOTTOM: A strong solar magnetic field blocks the same rays and could mean less clouds and clearer skies.

People have known for 200 years that there’s some link between sunspots and our climate. In 1800, the astronomer William Herschel didn’t need a climate model, he didn’t even have a calculator — yet he could see that wheat prices rose and fell in time with the sunspot cycle. Since then, people have noticed that rainfall patterns are also linked to sunspots.

Sunspots themselves don’t make much difference to us, but they are a sign of how weak or strong the sun’s magnetic field is. This massive solar magnetic field reaches out around the Earth, and it shields us from cosmic rays. Dr Henrik Svensmark has suggested that if more cosmic rays reach further down into our atmosphere, they might ionize molecules and help “seed” more clouds. As it happens, this year, the sun has almost no sunspots, but for much of the late 20th Century, the solar magnetic field was extremely active. If the theory is […]