By Justin Worland
December 21, 2015

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3.5°C

This is how much temperatures would rise by 2100 even if nations meet initial Paris pledges to reduce carbon emissions; this rise could still submerge coastal cities and drive over half of all species to extinction.

2°C

To meet this minimum goal, the Paris accord requires countries to tighten emissions targets every five years. Even this increase could sink some islands, worsen drought and drive a decline of up to a third in the number of species.

1.5°C

This is the most ambitious goal for temperature rise set by the Paris Agreement, after a push by low-lying island nations like Kiribati, which say limiting temperature rise to 1.5°C could allow them to survive.

0.8°C

This is how much temperatures have risen since the industrial age began, putting us 40% of the way to the 2°C point.

0°C

The baseline here is average global temperature before the start of the industrial age.

Write to Justin Worland at justin.worland@time.com.

This appears in the December 28, 2015 issue of TIME.

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