Five countries’ carbon emissions caused $6tn in global losses, study finds

Scientists have been able to calculate the economic impact of individual countries' carbon emissions on the global economy, in what they say could become a "game-changer" for climate litigation.

The research by US-based Dartmouth College estimates that the greenhouse gas emissions from only five countries between 1990 and 2014 resulted in global economic losses of up to $6tn (£5tn), with nations in the global south having been hit hardest.

The study's conclusions, published in the journal Climatic Change, provide a basis for nations to make legal claims for economic losses tied to carbon emissions, according to the researchers.

“Greenhouse gases emitted in one country cause warming in another, and that warming can depress economic growth,” said Justin Mankin, senior researcher of the study. “This research provides legally valuable estimates of the financial damages individual nations have suffered due to other countries’ climate-changing activities.”

The study is the first to assess the economic impacts that individual countries have caused other countries through their contributions to global warming.

To make the calculations, the researchers sampled 2 million possible values for each country-to-country interaction and used a supercomputer to crunch a total of 11 trillion values to quantify and address cause-and-effect uncertainties. The scientists then drew direct connections between cumulative carbon dioxide emissions per nation to gross domestic product (GDP) gains over the period, for the 143 countries for which data was available. 

The findings identify China and the United States as the world's two leading emitters, being directly responsible for global income losses of over $1.8tn each from 1990-2014. Meanwhile, Russia, India, and Brazil caused losses individually exceeding $50bn each for the same period.

The analysis also shows the damage done by a single emitter to another country's economy. For example, US carbon emissions cost Mexico a total of $79.5bn in GDP losses in the period, while also producing gains of $247.2bn of GDP in Canada. The figures used have been adjusted to reflect inflation. 

"The statement that it is possible and scientifically credible to link an individual actor to an individual tangible impact is a statement that has not been made robustly in previous work," said study first author Christopher Callahan.

“We have quantified each nation’s culpability for historical temperature-driven income changes in every other country.”

The rise of global temperatures caused by climate change can cause economic losses for countries in the global south, as it results in lower agricultural yields and worsening population health. At the same time, for some northern countries, global warming can raise output by boosting crop yields.

Although the research identifies certain economic gains resulting from climate change, the researchers highlight that these gains do not negate the losses suffered in other locations.

“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,” Mankin said.

The research team said 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, and hope that the framework can be used to identify national culpability. 

In the past two decades, the number of climate-related lawsuits has risen significantly. However, so far, climate-related legal action has mostly targeted major oil companies and other corporates rather than nation states.