What are denialists worried about?

The denialists continue to scream that any discussion, let alone actual policy, to do something about climate change is nothing less than the road to some marxist stone age.  Why? At moment nothing at all has been accomplished in curbing emmisions:

Emissions rose 5.9 percent in 2010, according to an analysis released Sunday by the Global Carbon Project, an international collaboration of scientists tracking the numbers. Scientists with the group said the increase, a half-billion extra tons of carbon pumped into the air, was almost certainly the largest absolute jump in any year since the Industrial Revolution, and the largest percentage increase since 2003.

Well if that doesn't bother you, an article in Nature (behind paywall) indicates that there is a high risk that arctic permafrost will thaw, which could lead to a larger amount of methane being added to the atmosphere.  Paraphrased in Sciencedaily:

Permafrost thaw will release approximately the same amount of carbon as deforestation, say the authors, but the effect on climate will be 2.5 times bigger because emissions include methane, which has a greater effect on warming than carbon dioxide

The survey, led by University of Florida researcher Edward Schuur and University of Alaska Fairbanks graduate student Benjamin Abbott, asked climate experts what percentage of the surface permafrost is likely to thaw, how much carbon will be released and how much of that carbon will be methane. The authors estimate that the amount of carbon released by 2100 will be 1.7 to 5.2 times larger than reported in recent modeling studies, which used a similar warming scenario.