Although the following infographic implies that there is one carbon budget, the fact is that there are several budgets depending upon the maximum temperatures and likelihood of keeping under that temperature (66%, 50% and 33%). The Paris agreement that Canada signed said that the world should:
"[hold] the increase in the global average temperature to well below 2 °C above pre- industrial levels and pursuing efforts to limit the temperature increase to 1.5 °C above pre-industrial levels”.
The carbon budget in the October 2018 IPCC report was for emissions accumulated from January 2018. The poster below was designed for the earlier IPCC carbon budget.