Previously published research shows that a dangerous level of global warming will occur if carbon dioxide in the atmosphere exceeds a concentration of about 450 parts per million. That's equivalent to about a 61 percent increase from the pre-industrial level of 280 parts per million, but only 17 percent more than the current level of 385 parts per million. The carbon dioxide cap is related to a global temperature rise of about 1.8 degrees Fahrenheit above the 2000 global temperature, at or beyond which point the disintegration of the West Antarctic ice sheet and Arctic sea ice could set in motion feedbacks and lead to accelerated melting.

To better understand the possible trajectory of future carbon dioxide, Kharecha and Hansen devised five carbon dioxide emissions scenarios that span the years 1850-2100. Each scenario reflects a different estimate for the global production peak of fossil fuels, the timing of which depends on reserve size, recoverability and technology.

"Even if we assume high-end estimates and unconstrained emissions from conventional oil and gas, we find that these fuels alone are not abundant enough to take carbon dioxide above 450 parts per million," Kharecha said.

The first scenario estimates carbon dioxide levels if emissions from fossil fuels are unconstrained and follow along "business as usual," growing by two percent annually until half of each reservoir has been recovered, after which emissions begin to decline by two percent annually.

The second scenario considers a situation in which emissions from coal are reduced first by developed countries starting in 2013 and then by developing countries a decade later, leading to a global phase out by 2050 of the emissions from burning coal that reach the atmosphere. The reduction of emissions to the atmosphere in this case can come from reducing coal consumption or from capturing and sequestering the carbon dioxide before it reaches the atmosphere.

The remaining three scenarios include the above-mentioned phase out of coal, but consider different scenarios for oil use and supply. One case considers a delay in the oil peak by about 21 years to 2037. Another considers the implications of fewer-than-expected additions to proven reserves due to overestimated reserves, or the addition of a price on emissions that makes the fuel too expensive to extract. The final scenario looks at emissions from oil fields that peak at different times, extending the peak into a plateau that lasts from 2020-2040.

A quarter pounder with cheese takes .7 lts of petrol and leaves a 5.7 kg carbon footprint. This is equivalent to burning 3.1 kg of coal.

KAEP; all true; but my point about Titan went to the abiotic origin of hydrocarbons.

Geoff of Perth

from your post I think you're beginning to understand the arguments.. that's good. Sure there may be some dislocation because OPEC has refused to invest in production capacity, and the oil industry has to switch to more expensive sources.. but as for absolute limits, no sorry. Even the original proponents of the modern form of peak oil Cambell and Laherrere (you can find the orignal Scientific American article with a quick search), knew there was far too much unconventional oil to put any limits on production. However, they also claimed that there was no more offshore oil, and look what's happened?

You can have short term disruption (although I doubt it will happen, its arguable). But the activist's version of peak oil (as opposed to the original version)is dead.. time to move on..

cohenite, are you saying that you subscribe to the abiotic origin theory of geologic oil?