As we approach the targets given in Paris, the amount of precision we need on these allowable carbon budgets — to meet the temperature changes — is going to get sharper and sharper, and so we're going to need better climate models to address those carbon budget issues. (carbonbrief.org)
Research efforts on concepts like «tolerable windows» and «pathways» and «allowable carbon budgets» and the such are all rooted in this notion. (dotearth.blogs.nytimes.com)
The figure below shows various estimates of the allowable carbon budget to keep temperatures well below 1.5 C, where «well below» implies a 66 % chance of keep temperatures below 1.5 C warming (and a corresponding 33 % chance of exceeding the target). (skepticalscience.com)