Brookings: The economic case for staying in the Paris agreement

Nations who abandon the Paris agreement designed to tackle global climate change would ultimately be worse off economically despite some GDP benefits from reneging, according to a new analysis of the Paris climate deal by researchers with the Brookings Institution.

Why it matters: The study arrives at a fragile moment in global climate diplomacy, even as more research piles up about the dangers of failing to steeply cut emissions. The U.S. is preparing to abandon the deal and now Brazil's new far-right president is undercutting confidence in that country's green commitments.

What they did: The analysis models the macroeconomic effect on nations of participating in the deal compared to abandoning their pledges — both in terms of the "co-benefits" of reducing conventional pollutants and the effect of avoided CO2 emissions.

• "[W]e observe that co-benefits from reductions in conventional pollutants are sufficiently large that even without accounting for reductions in climate change, every region receives a net benefit from participating in the agreement," it states.
• Nations' self-determined emissions pledges that together form the backbone of the agreement have "significant macroeconomic spillovers across the global economy."
• The paper also aims to extricate what happens to specific nations countries from participating vs. pulling out.

What they found: The authors ran simulations based on participating vs. abandoning pledges for China (now by far the world's largest emitter), the U.S., and Australia.

• "We find that non-participation leads to economic gains for these countries relative to participating, illustrating the challenge of forging an international agreement with participation by all major emitters and fossil fuel producers," they found.
• But, but, but: "[W]e also find that if we account for the monetized climate and domestic co-benefits of emissions reductions, those countries are worse off if they unilaterally withdraw from the Paris Agreement than if they participate."

The big picture: The study shows that the Paris agreement "significantly reduces" carbon emissions relative to a business-as-usual case. But it also further confirms how much existing pledges, called nationally determined contributions, are nonetheless insufficient. Per the report...

Global CO2 emissions would be lower than baseline by 13 billion metric tons by 2030. However, the Paris policy scenario suggests that global CO2 emissions would not decline in absolute terms relative to 2015 levels, let alone follow a path consistent with a 2°C stabilization scenario.