In a just world the United States would pay back the $4 trillion dollars it owes, according to new research, for trashing the climate.
Global warming wasn't created equal. Rich, industrialized nations have contributed the lion's share of the carbon pollution to our currently-unfolding catastrophe—the more CO2 in the atmosphere, the hotter it gets, of course—while smaller, poorer, and more agrarian countries are little to blame. The subsequent warming from our carbon-stuffed skies will, naturally, impact everyone, often hitting the poorer countries harder. So, since the rich fueled the crisis that's about to soak the poor, they might help chip in to soften the blow.
That, in super-basic terms, is the concept of climate debt, which guides current emissions negotiations and efforts to distribute funds for adaptation to nations most affected by climate change. If you acknowledge, as the UN does, that there's a carbon budget—an amount of greenhouse gas pollution the world can collectively churn out before we land in dangerous warming territory, currently figured at a 2˚C threshold—then it follows that nations that have overstepped theirs should pay back those who haven't.
The question has always been who gets what and how much. And that's where Damon Matthews, a researcher at the Concordia University in Montreal, comes in. In a study published in Nature Climate Change, he attempts to quantify the amount of climate debt that polluting nations should owe the climate creditors—and comes up with some fairly staggering figures.
"The idea of a carbon budget is gaining traction," Mathews told me. He's primarily interested in demonstrating the inequality inherent in climate debt, he said. In his paper, Matthews looks at the amount of warming each country is responsible for, focusing in on a 1990 baseline (after NASA climatologist James Hansen publicly warned Congress of global warming, the problem can reasonably be said to have been brought to world attention) according to their fossil fuel emissions, as measured by the Global Carbon Project, on a per-capita basis.
Take the world's total carbon emissions, and "imagine a baseline where everyone has polluted the same amount," he tells me, "which they haven't." Those countries that have polluted more, per capita, are now in climate debt. Those that are under—small or developing nations, mostly—are climate creditors.
By this metric, Mathews finds that the US, which has emitted about 100 gigatons of carbon beyond the baseline since 1990, is culpable for 40 percent of the planet's climate debt, a humbling figure to be sure. Russia is a distant second, at about 9 percent, followed by Japan, Germany, Canada, the UK, and Australia. These are the world's climate debtors.
Now, if you calculate the debt using the US's own social cost of carbon—the dollar value damage each ton of CO2 pollution does, currently pegged at $40 a ton—then the climate debtors' total is damage is massive. There are 250 billion tons of carbon debt accumulated since 1990, Matthews figures, so that amounts to $10 trillion. Yes, trillion—$10 trillion that polluting industrial nations owe climate creditor nations like India, China, and Nigeria who have stayed under their carbon budgets. (In the case of China, it won't be for long.)
Seeing as how the US is responsible for 40 percent of those emissions—or 1 billion tons—it would owe $4 trillion. His paper divvies up the debt a couple different ways, too: By incorporating land use issues, which, thanks to deforestation, would land Brazil and Indonesia in the top offenders' circle, and by counting costs back to 1960, which makes the US even more culpable.
"No matter how you look at this picture, these numbers are really big," Mathews said in a statement, "much, much larger than even the most generous financial commitments currently pledged by countries to help with the cost of climate adaptation and damages in vulnerable countries." The UN Green Fund, designed, essentially to help balance climate debt, is currently capitalized at $10 billion in pledges from rich countries. That's barely a drop in the bucket, as Matthews points out: in 2013 alone, rich countries emitted 13 billion tons—or $520 billion worth—of carbon debt.
Those "really big" numbers are often nonstarters in real-world politics, of course—just imagine asking Congress to allocate $4 trillion to pay for America's historic debt obligation to the environment, and you can hear, crystal-clear, the sound of scoffing. And there will no doubt be quibbles with how he drew up his formula, which provisions were included or excluded, and so forth.
But it's a good way to envision the scale of the climate damage done by industrial nations, mostly the US, compared to the vast majority of countries coping with warming around the globe. Even China, "the world's factory," has nothing on the US's past penchant for whipping up carbon pollution. That's good to remember, as many continue to point to the developing world as a source of rampant pollution: The US is the historic cause of this problem, and has done very little to make amends for it.
Mathews, for his part, hopes that the formula will spark further discussion on how we might fairly allocate funding and resource provisions in forthcoming climate policy talks—especially at the gathering in Paris, where the world's best hope of securing a deal to draw down greenhouse gas emissions lays. It may be a utopian prospect to imagine that it will ever get paid, but even if it doesn't, merely by figuring that climate debt, it helps us recognize the historic inequity and scale of the crisis.
"The rest of the world is crying out for help," Mathews said, "and the developed world is digging in its heels, and refusing to pay its debts."