Mitigation Scenarios and Pathways

 ©Henrike Doebert / Climate Analytics
©Henrike Doebert / Climate Analytics

We explore the greenhouse-gas emission reductions necessary to achieve long-term global climate goals, such as holding warming below 1.5 and 2°C warming relative to pre-industrial levels. Analysing emissions scenarios from energy-economic models and other sources with coupled carbon-cycle/climate models leads to globally “allowed” ranges of emissions for different greenhouse gases, air pollutants and sectors, as well as associated time- and pathway-dependent mitigation costs and technology portfolios.


This technical note looks at the estimates of the remaining warming that have been used in the IPCC AR5 and in recent studies, and evaluates the consequences for carbon budget estimates to limit warming to 1.5°C.  
Accepted estimates of how much carbon we can still burn by the end of this century and keep temperature rise to below 2°C range from 590 to 2390 billion tons of carbon dioxide. The high end of this estimate does not take into account warming by non-CO2 emissions and was never intended to be used to address a real-world policy question. Consequently, this study finds that the most appropriate carbon budget estimate for keeping warming to below 2°C is in the range of 590-1240 billion tons of carbon dioxide.