Those models do suggest that failure to stem industrial exhaust will push global temperatures four degrees Fahrenheit above today's readings – well beyond a threshold many scientists fear will produce dreadful consequences. Sea levels under such a scenario rise at least nine inches - likely more – by century's end. Massive ice sheets are destabilized. The Arctic, hit the hardest, would undergo dramatic change.

"We are now completely in charge," said NASA scientist James Hansen, who was not a part of the study but who first urged Congress to stem emissions in 1988.

"We are going to determine the climate for our children and grandchildren. We're much more powerful than the natural forces.... We could be sending the planet back toward an ice-free state."

Hansen and others argue that the only way to avoid such a fate is to slap carbon-based fuels with a significant tax - $115 per ton of carbon dioxide emitted, or about $1 extra on each gallon of gasoline - as well as a heavy push into renewable and nuclear fuels.

A poll conducted by the London Guardian and published today exposes that gulf between what scientists and politicians think possible. While world leaders – and this NCAR study – suggest prompt action can still avert the worst consequences, a majority of scientists polled at a major international conference last month told the paper they fear society is incapable of such action and faces dangerous warming.

The NCAR study, whose authors also hailed from the Institute for Atmospheric and Climate Science in Zurich and from Climate Central, a website founded by NOAA Administrator Jane Lubchenco, took no sides in that debate.

The scenarios, the authors state, should be seen as "storylines" illustrating the outcomes of different choices. "It is clear that emissions reductions in the 21st century need to be large," they said.

"We do not claim they are necessarily politically or economically feasible.... The aim is to provide policy-relevant information for a range of options."

Douglas Fischer is editor of the Daily Climate. This article originally appeared at The Daily Climate, the climate change news source published by Environmental Health Sciences, a nonprofit media company.