For many approaching the climate debate it is a huge shock to find out how much our climate has varied in the past.
Even Prince Charles is allegedly confused about it:
Well, if it is but a myth, and the global scientific community is involved in some sort of conspiracy, why is it then that around the globe sea levels are more than six inches higher than they were 100 years ago?
Comical (and my sincere apologies to the Prince if he has been misquoted by the UK media), but unsurprising – as most people really have no idea.
Take a look at An Inconvenient Temperature Graph if you want to see how the temperature has varied over the last 150,000 and the last million years. And one graph reproduced here:
The last million years are incredible. Sea levels – as best as we can tell – have moved up and down by at least 120m, possibly more.
There are two ways to think about these massive changes. Interesting how the same data can be interpreted in such different ways..
The huge changes in past climate that we can see from temperature and sea level reconstructions demonstrates that climate always changes. It demonstrates that the 20th century temperature increases are nothing unusual. And it demonstrates that climate is way too unpredictable to be accurately modeled.
The huge changes in past climate demonstrate the sensitivity nature of our climate. Small changes in solar output and minor variations in the distribution of solar energy across seasons (from minor changes in the earth’s orbit) have created climate changes that would be catastrophic today. Climate models can explain these past changes. And if we compare the radiative forcing from anthropogenic CO2 with those minor variations we see what incredible danger we have created for our planet.
We will try and understand the ghosts of climate pasts in future articles.