Climate change is happening, it's almost entirely man's fault and limiting its impacts may require reducing greenhouse gas emissions to zero this century, the U.N.'s panel on climate science said Sunday.
The fourth and final volume of the Intergovernmental Panel on Climate Change's giant climate assessment offered no surprises, nor was it expected to since it combined the findings of three reports released in the past 13 months.
But it underlined the scope of the climate challenge in stark terms. Emissions, mainly from the burning of fossil fuels, may need to drop to zero by the end of this century for the world to have a decent chance of keeping the temperature rise below a level that many consider dangerous.
Failure to do so, which could require deployment of technologies that suck greenhouse gases out of the atmosphere, could lock the world on a trajectory with "irreversible" impacts on people and t
