Hsu quoted on 'dodgy' greenhouse gas data threatening Paris accord
Potent, climate-warming gases are being emitted into the atmosphere but are not being recorded in official inventories, a BBC investigation has found.
Among the key provisions of the Paris climate deal, signed by 195 countries in December 2015, is the requirement that every country, rich or poor, has to submit an inventory of its greenhouse-gas emissions every two years.
Under UN rules, most countries produce "bottom-up" records, based on how many car journeys are made or how much energy is used for heating homes and offices.
But air-sampling programmes that record actual levels of gases, such as those run by the UK and Switzerland, sometimes reveal errors and omissions.
China's approach to reporting its overall output of warming gases to the UN is also subject to constant and significant revisions.
Its last submission ran to about 30 pages - the UK's, by contrast, runs to several hundred.
Back in 2007, China simply refused to accept, in official documents, that it had become the largest emitter of CO2.
"I was working in China in 2007," said Dr Angel Hsu, from Yale University.
"I would include a citation and statistics that made this claim of China's position as the number one emitter - these were just stricken out, and I was told the Chinese government doesn't yet recognise this particular statistic so we are not going to include it."