If we continue with business as usual as 'skeptics' want, how much will the planet warm?

A fairly popular global warming contrarian argument (particularly with a certain CO2 Expeller) is that the planet won't warm very much over the next century, so we don't have to take serious steps to reduce carbon emissions. The IPCC modeled various scenarios in AR4, including A2 (moderate economic... show more A fairly popular global warming contrarian argument (particularly with a certain CO2 Expeller) is that the planet won't warm very much over the next century, so we don't have to take serious steps to reduce carbon emissions.

The IPCC modeled various scenarios in AR4, including A2 (moderate economic growth and some adoption of alternative and renewable energy sources) and B1 (a major move away from fossil fuels). I think it's fair to say that A2 is what most 'skeptics' propose (take small steps to slowly move away from fossil fuels), while B1 is more what proponents propose (take major steps to quickly move away from fossil fuels). Currently our CO2 emissions are actually on pace with scenario A1F1 - high economic growth and continued reliance on fossil fuels.

Scenario B1 results in atmospheric CO2 around 600 ppm in 2100, and a warming of about 1.8°C between 2000 and 2100. Scenario A2 is 850 ppm CO2 and 3.4°C warming over the next century.
http://www.skepticalscience.com/monckton...

In other words, in order to keep the rate of warming over the 21st century as low as it is now, we need to take major steps to move away from fossil fuels, as AGW proponents propose.

If we continue with business as usual as 'skeptics' want, how much do you think the planet warm?
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