Study finds new method to calculate carbon emission budget until Paris targets broken

Scientists have found a new way to calculate the total carbon emissions corresponding to Paris Agreement targets of 1.5 and 2 degrees Celsius.

A new study has showed that observed global warming so far and estimated carbon emissions together form a good indicator of the emission budget we are left with before we pass the Paris climate targets.

Looking at results from all available earth system models, the team of researchers from University of Exeter, Met Office and Imperial College, UK, found that they formed a “lovely straight line” linking emissions per degree Celsius of global warming till now.

For a given level of future global warming, they could then determine the total amount of carbon emissions, termed as “emergent constraints”.

The findings meant that best estimates of global warming and emissions up to the current day can be converted simply into estimates of the total carbon budget for the Paris climate targets, the researchers said.

The results also help solve the disagreement problem between various earth system models regarding an important question — how much global warming will we get for a billion tonnes of carbon emissions?

“This emergent constraint is elegant and powerful. It both uses observations to narrow the possible range of future emissions, but also lets us consider other greenhouse gases than just carbon dioxide. In this way, the remaining carbon budget is made much more policy relevant,” said Chris Jones, from the Met Office, and co-author of the study published in the journal Nature Communications.

The good news is that the latest study estimated emission budgets that are at least 10 per cent larger than the average value for the models, the team said.

However, the bad news is, they said, that if humankind continued emitting carbon at the current rate, we have a little more than a decade before we exceed the Paris 1.5 degrees Celsius target, even for decade-mean warming.

“Our study clarifies the climate problem that needs to be solved, and we hope that it will stimulate greater efforts to reduce our emissions to Net Zero,” said lead author Peter Cox, Director of the Global Systems Institute at the University of Exeter.