Last year, in the Arctic, atmospheric CO2 concentrations were measured at 400ppm. (referring to the text and links below the vid) If you search on line for historical CO2 levels, you’ll find a lot of comments that are of the opinion that 400ppm CO2 last occurred about 800 000 years ago…or maybe just a bit longer. The implication is that since that’s well within the span of human existence it doesn’t really matter too much. It’s fine; we’ve been here before.
One small detail is omitted from those 800 000 year punts though. Well, two actually. Firstly there is no indication from ice core samples of CO2 levels being as high as 400ppm. And secondly, ice core samples only stretch back 800 000 years.
According to sea bed core analysis, the last time atmospheric CO2 levels were around the 400ppm for any sustained period was during the Burdigalian stage of the Miocene. That’s 15 million to 20 million years ago. That’s the last time earth’s atmosphere had CO2 concentrations around the 400ppm for any sustained period of time.
And needless to say, we haven’t ‘been there’.
Just for some perspective on the time frames – 20 million years is about a third of the way back towards the extinction of dinosaurs, and our common ancestor, Homo Habilis (about 4 feet tall and with half our brain capacity) only appeared about 2.5 million years ago.
The point is this though, the world of 15 – 20 million years ago really is another world and climatically not one like anything we’ve ever experienced as a species. And the CO2 we have expelled into the atmosphere is creating precisely that world, right as I type, and right as you read.
The enormity and stupidity of what we have done boggles my brain. And it flops like a knackered fish brought to land when I reflect on politicians and industrialists jostling with one another across national boundaries for the right to expel even more CO2 into the atmosphere.
Like I said, ice cores record 800 000 years worth of climate. There was maybe a smidgen of ice somewhere 15 million years ago. But there was no Greenland ice sheet and no ice on the Arctic. And there would have been very little, if any, ice in Antarctica. (e.g. – Scientists variously estimate Lake Vostok in the middle of Antarctica has been isolated beneath ice for between 500 000 and about 1 million years) And I don’t think I’m being unreasonable to suggest similar comparitively ice free environments on the Himalayan and Tibetan Plateaus that contain the glacial feeds for many of the world’s major rivers.
And we can expect temperatures in line with the Burdigalian – ie 4-6 degrees C above pre-industrial levels by 2040 or 2050 according to the estimates of such conservative institutions as the International Energy Agency, the World Bank and others.
Sea level rise is another, less definite matter. Although I keep hearing 1000 years with regards Antarctica, the truth is that nobody knows with any accuracy how processes associated with melting work or how long they might take. What is known is that once ice shelves disintegrate (as is happening in Antarctica) there is nothing to hold glaciers, increasingly lubricated by melt water, up on the land. And it’s also known that ice in seawater has the same effect on sea level rises as melted ice. But sure, lets say 1000 years to get full on Burdigalian sea level rises in the order of 20m or 30m or whatever.
Now, I don’t expect anyone who is reading this to flick all their electrical switches to a permanent ‘off’ position. And I don’t expect people to suddenly refuse to drive cars or fly in planes. And I don’t expect you or anyone else to lend their heft to a force that will compel governmental agencies and institutions to take the type of radical and urgent actions that they and we really need to commit to.
What I do expect is for people to do nothing or nothing much by way of putting a stop to the burning of those carbon deposits that were laid down hundreds of millions of years ago.
And so I expect that we are in for a horrendously chaotic ride as the climate transitions from one stable state to another stable state. And, as a consequence, I expect millions, or possibly even billions now living to die – many within the memory of somebody, somewhere, who is alive today.
But that’s alright. Because maybe you’re up for promotion soon. Or maybe the Cullen Fund will yield you good returns for retirement. And maybe the next government will be better than the last government. And this plan; the one we are pursuing at the moment whereby we pretend everything’s okay on the basis that everything’ll be okay if we pretend hard enough that everything’ll be okay…it seems to be working, yup?
N.B. Anybody attempting to run an AGW denialist arguments will be banned. Them’s the rules. You don’t have to like them. You’ve been warned.