In the future, countries might sue climate emitters for the damage caused by global warming – and the sums involved are astronomical, a new study has shown.
A small group of countries have caused $6trn (£5trn) in global economic losses during the period covered by the study, 1990 to 2014.
Emissions from the US and China, the world's two leading emitters, are responsible for global income losses of over $1.8trn (£1.5trn) each in the 25-year period from 1990.
Economic losses caused by Russia, India, and Brazil individually exceed $500bn (£422bn) each for the same years.
The cumulative losses attributable to the five countries equals about 11% of annual global GDP within the study period.
Lead author Justin Mankin, an assistant professor of geography at Dartmouth, said: "Greenhouse gases emitted in one country cause warming in another, and that warming can depress economic growth.
“This research provides legally valuable estimates of the financial damages individual nations have suffered due to other countries' climate-changing activities."
Christopher Callahan, first author of the study and a PhD candidate at Dartmouth, said: "This research provides an answer to the question of whether there is a scientific basis for climate liability claims — the answer is yes. We have quantified each nation's culpability for historical temperature-driven income changes in every other country."
Warmer temperatures can cause economic losses for a country through many pathways, such as lowering agricultural yields, reducing labour productivity or decreasing industrial output.
In addition to losses, the research also values the economic benefits derived from warming caused by country-level emissions, but highlights that the large gains disproportionately benefiting some countries do not negate the losses suffered in others.
The research shows that the distribution of warming impacts from emitters is highly unequal, with the top 10 global emitters causing more than two-thirds of losses worldwide.
Countries that lose income are warmer and poorer than the global average and are generally located in the tropics and the Global South.
Countries that gain income are cooler and wealthier than the global average and are generally located in the middle latitudes and the North.
Mankin said: "Irrespective of the accounting, warm countries have warmed and lost income because of it, while colder countries have warmed but enjoyed economic gains.
“The responsibility for the warming rests primarily with a handful of major emitters, and this warming has resulted in the enrichment of a few wealthy countries at the expense of the poorest people in the world."
By creating an analytical framework that links emissions from individual countries to the losses and gains in every other country, the Dartmouth research team hopes to help resolve questions of climate liability and national accountability to inform climate policy.
Callahan said: "For the first time, we have been able to show clear and statistically significant linkages between the emissions of specific countries and historical economic losses experienced by other countries.
“This is about the culpability of one country to another country, not the effect of overall global warming on a country."
The team says that the study discredits the idea that climate mitigation is simply a "collective action problem", where no one country acting alone can have an effect on the impacts of global warming.
"Until now, the complexity of the carbon cycle, natural variations in climate, and uncertainties in models have provided emitters with plausible deniability for individual damage claims. That veil of deniability has now been lifted," said Mankin.
"Nations need to work together to stop warming, but that doesn't mean that individual countries can't take actions that drive change. This research upends the notion that the causes and impacts of warming only occur at the global level."
The study sampled two million possible values for each country-to-country interaction. In total, 11 trillion values were calculated on a supercomputer operated by Dartmouth's Research Information, Technology and Consulting.
"This is the first research to integrate and quantify all of the uncertainties in each step of the chain between emissions and economic impact," said Callahan. "We are not addressing the question of whether fossil fuels have been good or bad for economic growth, but how to compensate for the damage caused by the warming from those emissions."
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