Two Degrees

With only two degrees warming, the oceans turn increasingly acidic, wiping out calcareous plankton and further hitting surviving coral reefs much of the marine food chain endangered.
One summer in every two has heatwaves as strong as the 2003 disaster in Europe, when 30,000 died.
Drought, fire and searing heat strikes the Mediterranean basin.
Greenland tips into irreversible melt, accelerating sea-level rise and threatening coastal cities around the world.
Hundreds of millions live in peril of the rising seas.
Polar bears, walrus and other ice-dependent marine mammals extinct in the Arctic.
Glaciers in Peru disappear, threatening water supplies to Lima.
Declining snowfields also threaten water supplies in California.
A third of species worldwide face extinction as the climate changes the worst mass extinction since the end of the dinosaurs.

Notes from Mark Lynas author of Six Degrees: Our Future on a Hotter Planet Two Degrees video description from National Geographic