Two degrees is the internationally-agreed target for limiting global warming, and has a long history in climate policy circles . Ambition that we can still achieve it is running high as climate negotiators gather in Lima to lay the groundwork for a potential global deal in 2015.

via carbonbrief:
http://www.carbonbrief.org/blog/2014/12/what-happens-if-we-overshoot-the-two-degree-target-for-limit...