Some groups have taken a stab at calculating what climate change will cost the world, or conversely, how much humanity would save by becoming more sustainable. Earlier this month, the Global Commission on the Economy and Climate tallied the number at a truly massive $26 trillion in savings by 2030.

Getting a slice of those savings requires figuring out which actors stand to lose the most as the climate changes, whether that’s countries, companies, or even individuals.

And this is where the idea of the social cost of carbon comes in. It’s a policy tool that attaches a price tag to the long-term economic damage caused by one ton of carbon dioxide, hence the cost to society. It’s related to a carbon tax (more on that below), and it serves as a way to distill the vast global consequences of climate change down to a practical metric.

Critically, it’s also the foundation of US climate policies, including the Clean Power Plan. Revising this number down has been a key part of the Trump administration’s strategy to roll back environmental rules. Under Obama, the social cost of carbon was set at $45 per ton of carbon dioxide; under Trump, it’s as little as $1.

A new study published Monday in the journal Nature Climate Change calculates the social cost of carbon down to individual countries. This adds an important bit of nuance because climate change is going to cost some countries more than others, a fact that’s lost when you try to tabulate a global average.

Source: Climate change is a global injustice. A new study shows why.