The global carbon budget or how much CO2 is too much
To say climate change is complex, would be the mother of all understatements.
Thankfully for us, the scientists at IPCC have simplified the complexity of the issue a bit by coming up with something known as ‘The Carbon Budget’.
While limiting global average temperature rise to 2 degrees is the internationally agreed goal, the input which governs it is the amount of CO2 and other greenhouse gases we emit over the next few years. And ‘The Carbon Budget’ is the total amount of CO2 we can emit before 2 degrees is no longer attainable. This gives us an actionable goal and helps inform policy decisions regarding fossil fuel usage.
It is possible to come up with such a budget because global temperature rise has a predictable relationship with cumulative CO2 emissions. Thus, the scientists have also been able to come up with budgets for 1.5 and 3 degrees temperature rise as well.
Given the complexity of our climate system, there is some amount of uncertainty associated with the carbon budget. As a result the budget for a particular increase in temperature is also associated with a probability of achieving it.
For ease of discussion, we will just be focusing on the budget which gives us a likely (66%) chance of staying below 2 degrees.
