Climate change is a menace. The Intergovernmental Panel on Climate Change just issued a report showing how serious the situation is. If warming continues on its current trajectory, the report warns, then by the end of this century average temperatures will be 4 degrees Celsius higher than at the start of the Industrial Revolution.

That may not sound like a big rise, but in fact the results will be catastrophic. Already, the world has warmed by 1 degree Celsius since the Industrial Revolution started, and the effects are starting to be apparent -- the ice in the Arctic is vanishing, devastating hurricanes like Michael and Maria are becoming more common, and wildfires are gobbling up homes and businesses in California.

An additional 3-degree rise would be far more dire -- large parts of major coastal cities would be flooded and become uninhabitable, global food production would be in danger, storms and heat waves would reach epic proportions, and flooding and starvation would create waves of desperate refugees. Even a rise of only 1 more degree -- which now seems inevitable -- will carry serious consequences.

The effort required to halt climate change will be intense. The IPCC estimates that in order to limit global warming to the relatively safe level of 1.5 degrees Celsius, the world would need to eliminate coal power and invest $2.4 trillion a year in green energy technologies. That is about 3 percent of global economic output, or 10 percent of global capital formation. It’s doable, but daunting.

There’s one huge problem with this plan, however -- the bulk of this massive, unprecedented investment will have to be done not in wealthy nations, but in developing countries. And one developing country looms much larger than the rest. China now releases almost as much carbon dioxide as the US and Europe combined.

The true imbalance is much larger than it appears. Developed countries grow slowly -- perhaps around 2 percent a year. China, because it’s still catching up, grows much faster, at around 6.5 percent. That rapid growth is why China’s emissions have soared since 2007. As China continues to catch up, its already enormous share of global emissions will only grow, unless it takes dramatic steps to decarbonize its economy. To its credit, China has made moves to limit coal use. But the country’s emissions continue to rise.

This leads to a painful but inescapable truth. The US should ban coal power, tax carbon heavily and spend lots of money on building green energy infrastructure. But without a huge change in China, none of that will matter.

That truth will naturally sit uneasily with Americans, who as a group have grown accustomed to being the driver and arbiter of world events. Being dependent on the actions of foreigners to save US cities, crops and homes is disconcerting and unfamiliar. Many will be tempted to escape into fantasy, declaring that climate science is overhyped, or that a halt in rich-country growth will be enough to solve the problem. Others will desperately cling to the hope that by setting a good example, the US can cause China to change by moral force alone.

Americans should think about ways that they can encourage China to reduce its carbon emissions.

One idea is to tax products from China based on their carbon content. Unfortunately, this is likely to have at best a modest effect. There is a popular misconception that US emissions have decreased only because they’ve been outsourced to China via offshoring of polluting industries. But when emissions are calculated based on how much countries consume, the basic situation between the two nations looks much the same.

A better idea is to actively encourage China to give up coal. China, due to coal use and its manufacturing-heavy economy, uses more carbon to produce each dollar of gross domestic product than most other countries.

There is therefore lots of scope for improvement. The US should consider both carrots and sticks to make that happen. ARPA-E, the US’ energy-technology research agency, should be dramatically scaled up. Either all technologies produced by ARPA-E should be given to China for free, or the agency turned into a joint venture with China, ensuring that Chinese companies are able to replace coal with solar and wind as quickly as possible.

In many cases, it is bad when China copies American technology -- in this case, it’s exactly what the planet needs. Of course, these technologies should also be given to India, Africa and other developing countries seeking to lift their people out of poverty.

Another potential approach is conditional tariffs on Chinese products. Instead of only taxing the carbon content of Chinese-made goods, the US could threaten to put tariffs on all Chinese products unless it agrees to leave more of its coal permanently in the ground. Banning exports of coal from the US, and heavily subsidizing exports of solar and wind technology, would also help make coal less attractive around the world. Tariffs could also be placed on coal exporters like Australia, Indonesia and Russia.

Even with measures like this, the degree to which the US and Europe can force China into going green is limited. To a large extent, the fate of the planet is now out of the developed world’s hands. But that isn’t an excuse for doing nothing.


Noah Smith
Noah Smith is a Bloomberg Opinion columnist. -- Ed.

(Bloomberg)