People rally at Lafayette Square in front of the White House on June 1, 2017, to protest President Trump’s announcement that the United States would pull out of the Paris climate agreement. (Salwan Georges/The Washington Post)

Last June, President Trump announced that the United States would withdraw from the 2015 Paris agreement on climate change. How are the Paris goals looking, a year later?

It may be too early to assess whether the Paris signatories are on track with their pledges for the year 2030, but rising carbon dioxide emissions in Asia and Europe, in particular, are a troubling sign. The Paris agreement outlined steep emission reductions to meet the stated goal of limiting global warming to two degrees Celsius.

The 1.4 percent increase in global carbon dioxide emissions in 2017 is itself troubling but not surprising. Global economic growth is one obvious culprit — the world economy grew by 3.7 percent in 2017. This growth created demand for extra energy, which means more oil, natural gas and coal combustion. Regardless of U.S. participation in the Paris agreement, rapid global economic growth increased the use of fossil fuels.

More fundamentally, though, political-science research shows that national governments have only limited ability to control a country’s emissions. Great uncertainties surround both future emissions and the impact of different new policies.

With or without the Paris agreement, it’s hard to know what each country’s emissions levels will look like in the future. Here are four policy areas to watch:

1) Governments cannot credibly commit to long-term policy

In climate politics, governments simply cannot promise that their climate policies will continue indefinitely, as the next government may decide to overturn the policies. Democratic governments face elections every few years, and dictators can be unseated by coups and revolutions.

Given these political realities, climate policies often have short life spans — and this can be a major barrier to effective climate policy. From renewable-energy subsidies to carbon-emissions trading, governments can formulate and implement policies now and hope that they stick. But if the policies prove unpopular — as costly policies often do —  and have few loyal supporters, they will fall by the wayside as political fortunes wax and wane.

2) Leaders want to steer clear of blame or failures

Governments are often also loath to commit to targets they might not meet. It’s one thing to underpromise and overdeliver — and quite another to overpromise and underdeliver. When governments set their targets, they worry that they will look ridiculous when they fail to meet their own ambitions and come under criticism by other governments. In the Paris agreement, most countries’ initial pledges were generally conservative and not enough to meet the two-degree target.

In practice, this means that governments hedge their bets by making vague or trivial commitments. So a country that doesn’t rely on coal might ban coal use, for instance. Or a country could pledge net zero emissions by 2050 — a goal so far into the future that it has no practical relevance.

When the Group of 20 —  the world’s largest economies — “reiterate [their] commitment to sustainable development,” the commitment itself is vague enough that world leaders cannot possibly fail to honor the promise. Or when countries like France, which uses hardly any coal in power generation, promise to shut down their coal-fired power plants, they don’t have to do much to honor the commitment.

3) The Paris agreement is built on the principle of national sovereignty

The 1997 Kyoto Protocol assigned specific emissions targets to industrialized countries. In contrast, the Paris agreement is a bottom-up arrangement and asks countries to choose their own ambition level, or target. The agreement’s pledge-and-review system means countries will review and comment on each other’s progress every few years.

This arrangement is a nod to the principle of national sovereignty in climate diplomacy. After 25 years of experience, negotiators recognized that governments are not ready to commit to reducing their emissions. The future is uncertain, and policies come and go, so commitments to future emissions reductions are not credible and could backfire when they are not met.

But the sovereignty-focused Paris terms raise new concerns, given the global increase in greenhouse gas emissions in 2017. If major emitters are not on track to reduce their emissions, who will cast the first stone? The pledge-and-review approach can work when the vast majority of countries are on track, as the few detractors would face pressure to act. But if nobody is on track, then it becomes easier and less awkward to just say nothing.

4) The future of our climate is uncertain

Governments seem neither willing nor able to commit to ambitious emissions-reduction targets, and the Paris agreement gives them a lot of room to maneuver when it comes to promises. Aspiring to limit global warming to 1.5 or 2 degrees Celsius can guide the international community in the right direction and highlight the magnitude of the challenge, but the range of possible future climates is wide. Against this backdrop, here are two things to watch.

First, progress in mitigating climate change will come from policies that are difficult to reverse and create their own political support. Policies that furnish large gains to politically influential groups can survive over time. For example, renewable-energy policies that create profits for politically powerful farmers have proven durable, regardless of electoral outcomes.

Second, what China does is a particularly important question mark. In 2017, China’s coal use increased for the first time in three years while oil and gas demand continued to grow. Under the Paris agreement, China has promised that its carbon dioxide emissions will peak by 2030 — an unambitious target — but last year’s numbers suggest that China’s future emissions are very difficult to predict.

If China continues to invest in clean energy and move away from heavy industry and construction, its emissions may begin to decrease soon and bring the world back on track. But if China’s fossil-fuel demand continues to grow, it will be very hard for the rest of the world to fill the gap.

Johannes Urpelainen is the Prince Sultan bin Abdulaziz Professor of Energy, Resources and Environment at the Johns Hopkins School of Advanced International Studies. He is also the founding director of the Initiative for Sustainable Energy Policy (ISEP).