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Ice Ages Linked to Plate Tectonics
CorSci81 writes "A study by scientists at Ohio State University indicates the possibility that ice ages may be triggered by plate tectonics. Scientists speculate that the current ice age may have been triggered 40 million years ago by the uplift of the Himalayas, and this study provides further support by linking a much earlier ice age 450 million years ago with the uplift of the Appalachian mountain range. Additionally, this study reinforces the notion that CO2 concentration in the atmosphere is a major driver of climate."
"Because we are currently living in an ice age -- or, more precisely, in a slightly warmer interglacial period within an ice age -- CO2 levels worldwide would ordinarily be low; but scientists believe that humans have raised CO2 levels by burning fossil fuels."
This study actually contradicts nothing. This idea had been around for sometime, this is just the latest study to offer for evidence in support. What has become clear to climate scientists (and was impressed upon me during my graduate studies in that field) is that climate is a very complicated, non-linear, multivariate system. The Milankovich cycles were one proposed theory for ice ages, linking natural cycles in Earth's orbit to ice ages, but it quickly became clear that wasn't the entire story. One of the questions scientists struggled with for a long time is "How do you start an ice age?" For long periods in Earth's history there have been intermittent ice ages, but they seemed to have no periodicity or pattern. Milankovich cycles definitely control whether the climate is glacial or inter-glacial during a long term ice age, but if the climate is already in a "warm" state they lack the oomph to trigger an ice age. This research provides one clue to the answer. Other proposed solutions have to do with the arrangement of the land masses on Earth's surface, and ultimately they are all probable factors.
Regarding green house gases, one of the things this study does is reinforce the link between CO2 and climate state. Weathering is one way of removing a lot of CO2 from the atmosphere over long periods of time, and is part of the reason why Earth isn't more like Venus. Geologic forces removed a huge fraction of Earth's primordial CO2 from the atmosphere, more than we could ever hope to release by burning all of the fossil fuels on the planet.
If you look over geologic time scales, yes, we are in an ice age. People confuse ice age with glacial and inter-glacial periods. The trend for the last 40 million years has been sharp warming to temperatures similar to what we have experienced for roughly the last 10,000 years, followed by a slow decline over the next 100,000 or so years until you reach a minimum, then a sharp spike, etc. What is special about our current interglacial period is it has gone on for 10,000 years and it's suddenly getting warmer. There is some indication our current interglacial period has been somewhat long-lived even before we started pumping fossil fuels into the atmosphere, but the recent warming is more strongly correlated with the industrialization of our species. The typical interglacial temperature maximum for our ice age seems to have been in the ballpark of a few hundred to maybe a couple thousand years, a number we've far exceeded.
See my above comment. Ice age refers to the climate being cool on average over the past few million years. This is certainly punctuated by warm inter-glacial periods, but it is (or at least was) still an ice age.
Thank you for repeating a classic anti-science myth, please come again.
We're having a special on "Teh scientists wur all claiming global cooling in the 1970s" if you'd like to try it.
The Appalachians have actually undergone three orogenic (mountain-building) events. The biggest of these was the Taconic, which is what they're talking about in the article. So conceivably, it could happen again, but it would be a long time in the works.
This guy's the limit!
Go Bucks!!
For most of the Earth's history there has been no year-round polar ice like there is now. Until the ice caps melt we're still in an ice age. Read this article for more details.
"By God are you implying that global temperature is a complex system with no single cause for temperature fluctuation?"
Over millions of years certainly, over a couple of hundred years the long term "causes" (orbit, tilt, tectonics, ect) simply drop out of the equation as irrelevant.
How not to attribute climate change, (nice graph). It's also interesting to note that 20th century warming would actually be a slight cooling if human CO2 emissions were removed from the models.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.