A successful Paris climate treaty may not be enough to keep temperature rise below 2 C, study warns

Diplomats gathering in Paris face a tall task in trying to unite 190-plus countries behind a plan to fight climate change. Yet a success in Paris may not, by itself, be enough to prevent dangerous warming of the planet in the decades to come, a new study warns.
The report in the journal Science suggests that the Earth can avoid the most disruptive impacts of climate change only if the Paris agreement is a first step, followed by more ambitious cuts in greenhouse-gas pollution in future years.
In fact, without further emissions reductions, there is “virtually no chance” that global temperatures will stay below the threshold that many scientists say is safe, a maximum increase of 2 degrees Celsius (3.6 degrees Fahrenheit) over pre-industrial averages, the authors said.
The release of the report comes four days before the start of the Paris talks, when world leaders will try to cement an international accord to stop the sharp rise in atmospheric levels of carbon dioxide and other heat-trapping gases from fossil-fuel burning. More than 150 countries have announced pledges to reduce or scale back emissions through the year 2030.