China's emissions are more than double those of the US, but historically, the US has emitted more than any other country in the world.
There are many factors to consider when judging a country's climate credentials, and as leaders gather in Glasgow, Scotland for COP26 from Sunday, the US' and China's plans will be in the spotlight.
Here's how the two stack up against each other. In 2006, China overtook the US as the world's biggest emitter of carbon dioxide (CO2) -- the most abundant greenhouse gas in the atmosphere.
In 2019, the last year before the pandemic hit, China's greenhouse gas emissions were nearly 2.5 times that of the US', and more than all the world's developed countries combined, according to an analysis from Rhodium Group. In terms of CO2-equivalent -- which is a way of measuring all greenhouse gases as if they were CO2 -- China emitted 14.1 billion metric tons in 2019. That's more than a quarter of the world's total emissions. By contrast, the US was responsible for 5.7 billion tons, 11% of total emissions, followed by India (6.6%) and the European Union (6.4%).