One Degree

Deserts invade the High Plains of the United States, in a much worse repeat of the 1930s dustbowl. Whilst the epicentre is Nebraska, states from Canada in the north to Texas in the south suffer severe agricultural losses.
Mount Kilimanjaro loses all its ice.
The Gulf Stream switches off perhaps, plunging Britain and Europe into icy winter cold.
Irreversible feedbacks take hold in the Arctic as ice disappears, and the permafrost line shifts north.
Rare species wiped out in the Queensland rainforest, Australia.
Coral reefs around the world suffer increasing losses from bleaching and are wiped out. Coral atolls submerge under the rising seas.

Notes from Mark Lynas author of Six Degrees: Our Future on a Hotter Planet

One degree video description from National Geographic