Monday, 7 December 2009

Climate News - What's actually important?

On the news front, the argument is hotting up on every side. Ignoring ClimateGate, there have been many stories detailing how temperature records have been "modified". However, there is one story that should be shouted from the roof-tops:

The Climate Change bandwagon is based on the logic that what we're experiencing now is unprecedented and therefore caused by human emissions. Historical records, unfortunately, disagree. There are many records of what's called the Medieval Warm Period. This was commonly accepted wisdom until the Hockey Stick graph appeared, showing that temperatures have been flat for two thousand years. The Medieval Warm Period was quickly accepted as being a figment of people's imaginations, along with the Mini Ice Age (remember those paintings of Snow Fayres on the Thames?).

The Hockey Stick graphs were based on a few proxies, that weren't actually linked to temperature. This is why the "Nature Trick" was important. It didn't hide the decline in temperatures, it hid that the proxies used to show temperature were flawed. They were unable to show recent warming and were therefore also unable to show historic temperatures.

Actually, a recent paper (by the Nature Trick man himself) has rediscovered what Historians knew all along. There was a Medieval Warm Period, although they're not calling it that. The Romans had Vineyards pretty far north in England, Greenland was actually bloody Green. There's some debate over how warm it was. Some sources suggest that it was about 0.5c (roughly the rise we've had since the 1940s) warmer than 1997 (itself one of the hottest years ever due to an excessive El Nino effect).

Interestingly, there wasn't a great deal of CO2 emissions back in those days, so clearly something else was causing both the warming and then the cooling over the previous years. Also, the whole world wasn't under metres of water, so catastrophic sea level rises seem unlikely as well.

Maybe climate just changes? Looking at a graph of temperature for the last 400,000 years we can see that the warm bits (where we like it) are actually pretty short, usually interspersed with much longer periods of serious cold. We can see several occasions when the temperature was higher than today and the majority of the time where it was a lot lower. However, the times when it was as warm, or warmer are pretty short, before the world slips back into a natty ice coat for another 80,000 years.

Just looking at that graph, I'd suggest that we really shouldn't be worrying too much about the world being 1.1 degrees hotter in 2100, but focusing more on the ice. It's worth remembering that we're not talking about a bit of frost. During the last ice age, there was an ice sheet 3-4km (yes, 3,000m thick) on the UK. We're still recovering from it as the rock in Scotland slowly elastically expands from the sheer compression this much Ice caused.

I don't know about you, but I think I can cope with 1 degree hotter temperatures much better than I could with watching civilisation scrapped off large chunks of the Northern hemisphere.

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