Could changes deep within in the sun soon see us skating on a
frozen-over Thames? The question of the sun's role in climate
change - and the prospect of an icy future - pops up in the media
from time to time.
This morning, it was the BBC's turn on the Today Programme. The
slot did a pretty good job of explaining that although changes in
the sun have affected climate in the past, greenhouse gases are now
the dominant factor driving temperatures up.
The programme's topic
was the imminent
flip in the sun's magnetic field, the force responsible
for driving sunspot activity. Steve Tobias, professor of maths at
Leeds University, explained how this switch happens about every 11
years, when the sun's output is at the highest point in a natural
Asked whether the sun's waxing and waning contributes to climate
change. Professor Tobias explained:
"It does feed in but it's a very small
effect. The sun's total irradiance actually varies by a fraction of
a percent, so the direct forcing is very small … it may have
indirect effects for the climate but I think I should stress
current global warming trends are not really due to changes in the
Presenter Justin Webb pressed a bit more, saying "but years ago
the sun created an ice age, didn't it?"
The simple answer is yes. But as Tobias explained, human
activity is now the main driver climate change, not the sun - a
mistake that has led some parts of the media to suggest we're
headed for a '
mini ice age'. Here's a closer look at what the sun has to do
with our climate.