Estimated cumulative emissions from fossil fuel use, cement production and land-use change since industrialization began are
tonnes of carbon.
Cumulative emissions matter, because the total amount of carbon dioxide that can be released into the atmosphere is limited if we are to avoid dangerous climate change. The limit depends on:
How much warming should we expect per tonne of carbon released into the atmosphere?
At what level will global temperatures peak?
If temperatures rise by °C per trillion tonnes of carbon released into the atmosphere, to avoid more than °C of warming we need to limit total cumulative emissions to below tonnes of carbon.
Based on emission trends over the past 20 years, we expect the tonne will be emitted on
We would not release the tonne if emissions were to start falling now at