Variable behaviour of the sun is an obvious explanation, and there is increasing evidence that Earth's climate responds to changing patterns of solarmagnetic activity. ... If you look back into the sun's past, you find that we live in a period of abnormally high solar activity. ... It's a boom-bust system, and I would expect a crash soon. ... Having a crash would certainly allow us to pin down the sun's true level of influence on the Earth's climate. Then we will be able to act on fact, rather than from fear.