
In 2015, countries worldwide signed the Paris Agreement, aiming to keep the global temperature rise “well below 2°C” and limit this increase to 1.5°C.
To meet these targets, there are limits to the amount of carbon dioxide (CO2) that can be emitted. These are called carbon budgets. Every year we emit more CO2, these budgets shrink. (That’s because total warming is roughly proportional to cumulative CO2.)
In the chart, you can see estimates for how much CO2 the world can emit — from the start of next year — while staying below different levels of warming. This is based on having a 50% likelihood of staying below it; if we wanted to guarantee that we didn’t pass these temperatures, our budget would be much smaller.
To get a sense of perspective, we’ve compared each budget with the projected amount of CO2 that the world is expected to emit in 2025. This tells us how many years we have left if emissions stay at their current levels.
At current emission rates, the 1.5°C budget would run out around 2030. It seems implausible that global emissions will fall quickly enough to avoid this.
The 2°C budget would last until mid-century. By taking action on climate change, we buy ourselves more time and can avoid this level of warming.