NOTE: The relationship between CO2 and global temperature is not under debate by any reasonable people, and I don’t have space to address that issue here, so if you want to look into that, either send me a note and I’ll discuss it later, or go here and see if you can find your answers. It will have to suffice, for now, to say that the influence of CO2 on atmospheric temperature has been tested, calculated, retested, and confirmed repeatedly from the late 1800’s, through the military’s development of heat-seeking missiles, and is now the field of fourth-grade science fair projects.
So – while regional temperatures, may have risen comparable amounts in the last couple thousand years, what about CO2 levels? Since that’s what’s driving this temperature increase, and we know that when CO2 increases, it takes time for the temperature to rise in response, how does today’s CO2 level compare?
For the entire rise of human civilization, CO2 levels have never been this high. Really, though, that’s not very long on an evolutionary scale, and we have the data to look farther back in time, so let’s take a broader look, shall we?
If we look back over the last six hundred thousand years, global CO2 levels have not risen above 300 ppm. We’re at 396ppm right now.Forget human civilization, CO2 levels have never been this high in all of human history, plus a significant chunk of time time we spent evolving into humans. In fact, if we look at the record, CO2 levels haven’t been this high for fifteen million years, back when ape-like primates were just starting to show up. A reminder: CO2 levels are still rising fast.
So the claim that “this has happened recently” is clearly false.
So what impact do we expect all this to have on the planet’s ecosystems?
We’re going to look at historical climate shifts (and there have been some big ones) in a moment, but first I want to look at what’s happening right now. Starting with weather events, as the most obvious, there have been a string of record-breaking droughts and floods in every part of the world, all of which have a lasting impact on their ecosystems. In scanning the news, Russia, Pakistan, China, Somalia, Australia, The United States of America, Brazil – all of these areas have had devastating events in the last two years, with massive human and economic costs, but also with an impact on the ecosystems in those regions.
On a smaller level, individual species are already showing changes due to the rise in temperature in every region in the globe.
In the Atlantic off of New England, lobsters are changing their behavior in response to warmer waters, and causing problems for the lobster fishery there, which has been able to rely on seasonal behavior for generations.
In the waters off of Japan, Australia, and Florida, coral ecosystems are migrating towards the poles with astonishing rapidity.
That is what’s happening already, and remember – the warming we’ve seen so far is not all the warming we’re going to see, even if we were to cut emissions to zero tomorrow.
So what about past warming events?
Even the Paleocene-Eocene Thermal Maximum – the period discussed on the HotAir piece I linked at the beginning – had its increase in biodiversity in the Amazon region accompanied by a mass extinction. An extinction which was spurred by a 10,000 year doubling of CO2. At the current rate, about twenty times as fast, it’s almost inconceivable that there will not be significant damage.The Permian-Triassic extinction event, which I’ve talked about before, may also have been caused by sudden warming.
As a matter of fact, research published in 2008 indicates that all five of Earth’s big mass extinction events have been associated with a rapid rise in CO2 levels.
In summary, there is no actual evidence that rapid warming will be good for the planet’s ecosystems, and quite a lot of evidence that rapid warming will be very bad for them. We’re already in a mass extinction event caused by human activities such as fishing, hunting, and habitat destruction, and now we’re adding the added burden of a rapidly changing climate.
While life will doubtless continue, and some species will be able to adapt, it is all but certain that many, many other species will be unable to cope with the coming century or two.