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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."
We're doomed, I tell you, DOOMED!
I've fallen off your lawn, and I can't get up.
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.
"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.
Two points. One: no one ever said humans are the sole cause. That said, it's clear we are part of what's going on. Two: the implication of the full article is that CO2 has a very large effect on climate. In turn, this implies that the rapid increase in CO2 due to humans may have a very large impact on our climate in a very short time.
And in a sense you have hit the nail on the head. Global warming is very much a political/economic issue and much less a science issue. Even if science can say what will happen, the simple fact is we can't easily reverse what we have already done, which could have consequences for a few centuries.
Now I'll pose a different question to you... what is the cost of doing nothing vs. taking what actions we can to mitigate the risk? The simple fact is we're rolling the dice and there will be winners and there will be losers, and we don't know which will be which. Even if only the least severe scenarios prove to be true, rising sea levels alone present us with an economic burden that far outweighs the costs of doing something now. So we don't understand everything well enough to know the exact outcome; but do we really want to roll those dice? I know I'm not a gambling man.