AVOID has shown that limiting global warming to 2°C is possible but challenging. Early global action increases our chances of remaining below this level.
There is some flexibility in the year of peak emissions (between 2014 and 2020). However, a later peak year must be coupled with much stronger action to reduce emissions after the peak and attain a low or zero long-term level of net emissions in the medium to long term. Such strength of action may be beyond economic and technological feasibility. There is thus a strong argument for early action.
Emissions after 2050 matter. For instance an extra 100 years of CO2 emissions at just a fifth of the year 2000 level could add more than 0.3°C to peak warming.
Global average warming is only an indicator of the response of the climate system to global emissions. Additional quantities, such as rainfall, sea-level rise, ocean acidification, regional variations and changes in extremes all influence the climate change impacts on people and natural systems.