Blog Post

AEIdeas

The atmosphere does not respond to greenhouse gas emissions per capita or scaled by economic size or to “fairness,” only to the quantity of emissions. The latest data on those quantities reinforce that (prospective) American policy-makers who see climate change as an unparalleled risk must be ready to coerce China.

The Netherlands Environmental Assessment Agency (NEAA) started measuring greenhouse emissions 30 years ago. They have since built a comprehensive and statistically consistent global time series. They don’t rush to estimate global emissions even before the year in question ends, odd yet routine behavior elsewhere.

It’s common to call China and the US “the two largest emitters” or the like. The NEAA’s just-updated data show that is accurate, yet badly misleading. The data put Chinese 2018 CO2 emissions of 11.18 billion metric tons at more than twice American and roughly equal to that of the US plus the EU plus India.

The China-US gap dwarfs other numbers thought to be important. China became the second-largest national emitter in 1987, passing the then-USSR. From the start of 1987 through the end of 2018, total Chinese emissions were 18 billion tons larger than American. That gap is larger than climate-maligned Australia’s total emissions from 1970 (first year recorded) through 2018.

A man smokes as he rides in smog during polluted day in Beijing, China, December 20, 2016. Via REUTERS/Stringer

Still, the US led in annual emissions for most of this period. In 2005, China took over and the gap between the countries has widened each year since. From 2005 through 2018, Chinese emissions were 56 billion tons larger than American. That gap is larger than the EU’s total emissions over the period.

Absent drastically different policies, China will continue to emit 5.5-6 billion more tons of carbon than the US every year. It is hardly scientific to treat the two as comparable; it would be more accurate arithmetically to lump Nigeria – at 110 million tons of emissions in 2018 — together with the US.

Against the numbers, it is frequently argued that the US must act first for China to be willing to make difficult changes. American emissions in 2018 were about the same as they were in 1993. From 1993 to 2018, the correlation between same-year American and Chinese emissions is -0.5. The US has capped emissions for a generation and China has not followed.

President Obama’s two terms are a very small sample but one where the US attempted to lead on climate change and induce China to follow. The emissions correlation during his time in office is -0.7. China may have moved more definitively in the opposite direction.

The good news is Chinese emissions growth has slowed, climbing 400 million tons from 2013 to 2018. The largest increment to emissions over this period belongs to India, at near 600 million tons. Moreover, India’s level and recent trend look in 2018 very similar to China’s in 1991. India could lead the world in the increment to emissions for decades.

If the goal is to curb global emissions growth from this point, the critical actions are aimed at sharply changing India’s trajectory. Its economy is small enough that large-scale financial and technological transfers from the US and other rich countries may be effective. It’s of course possible that emissions will rise as rapidly with aid as without — India seeks to develop, not control carbon.

A much harder objective is cutting global emissions outright. In this case the first and foremost target can only be China, which by itself accounted for over half the 1976-2018 increase in annual global emissions. China’s economy is large and difficult to influence, even if the US and others were willing to unconditionally offer the necessary level of assistance.

These facts imply conditions and enforcement. During the 2020 campaign, Democratic candidates and ultimately the presidential nominee will contrast their stress on limiting emissions to general Republican disinterest. Without a willingness to act coercively, India’s trend and China’s level mean capping emissions may not work and cutting emissions would rely largely on a leap of faith.