Now that's what I call long term effect!

Fossil fuel damage could last millennia

Column -- Burning all known reserves of fossil fuels, from Alberta's oilsands to China's vast stores of coal, would have much graver long-term consequences than previously thought, according to climate scientists who have peered far into the future. "Not only are we going to mess up our kids' and grandkids' lives, we are going to be interfering with the way the planet works for thousands of years," says climate scientist Alvaro Montenegro, noting that much of the carbon emissions would persist in the atmosphere more than 5,000 years and drive up global temperatures for millennia. Using sophisticated computer models, Montenegro and colleagues at the University of Victoria and the University of Chicago assessed the impact of consuming all known reserves of fossil fuels until they run out in 2300. Their simulations assume that the carbon dioxide producing by burning the fuel would waft into the atmosphere as it does today. "If we keep doing what we're doing right now, and the only thing that (stops) us from burning fossil fuels is the end of fossil fuels, that's what the experiment represents," says Montenegro, who presented the findings at an international meteorological conference in Newfoundland Wednesday. Asking what might happen if humans burn up all fossil fuels is pertinent today, he says, because global emissions continue to climb despite decades of talk about cuts. The scenario developed by Montenegro's group followed the UN panel's "business as usual" emissions path. According to that projection, oil, gas and coal consumption would continue on its current trajectory until 2100, then taper off over 200 years as supplies dwindle. Some 5,134 billion tonnes of carbon, locked underground for millions of years, would wind up in the global atmosphere. Supercomputers ran the models to calculate how the climate would respond in the 4,500 years after the emissions finally stop. The scientists concluded that average temperatures around the globe would soar six to eight degrees Celsius and would remain at least five degrees higher than pre-industrial levels for more than 5,000 years.
(Calgary Herald 070531)

The skeptics of course will say that projecting out 5,000 years is completely indefensible, which may be true, but the concept being presented isn't that difficult to predict - that dire consequences wait for the planet for many many centuries if we release all the sequestered carbon at a much faster rate than the planet can manage through its natural processes. Of course, I'm sure humanity (if we still can) will be forced to artificially assist these processes to mitigate the mess we've created in order to keep the planet from baking to a crisp.

This Australian Broadcasting Company documentary is very well done, and describes the possibly theories to explain periodic fossil fuel generation, and what might happen in the future if we return to a high-temperature planet.