In DepthCLIMATE POLICY

Five years in, Paris pact still a work in progress

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Science  18 Dec 2020:
Vol. 370, Issue 6523, pp. 1390
DOI: 10.1126/science.370.6523.1390

Five years ago, as world leaders celebrated reaching a landmark climate change agreement in Paris, green floodlights illuminated the Eiffel Tower and Arc de Triomphe with the message “Accord de Paris c'est fait!” (The Paris agreement is done!). But last week, as nations met to review the Paris agreement's progress and set new goals, the slogan might have been “travail en cours” (work in progress). Some nations have made modest progress toward the goal of the pact: keeping average global temperatures “well below” a 2°C rise above preindustrial levels. But the steps taken so far are far too little to reach that goal and stave off severe climate impacts.

If the Paris pact got a grade “based on whether we have any prospect of meeting a 2°C target … it's probably a D or an F,” says Michael Oppenheimer, a climate scientist and policy expert at Princeton University. At the same time, he says, the deal has made a “real difference” by helping make climate change “a top concern of all countries.”

Overall, global emissions of warming gases reached a record high in 2019, according to a new U.N. report. This year, as economies faltered and people avoided travel, emissions are set to fall by about 7% compared with 2019, according to a new estimate by an international team of scientists in the journal Earth System Science Data. But emissions are expected to bounce back as economies revive.

Still, the temperature spikes predicted for later this century will ease slightly, if countries stick with measures they have already taken since Paris. Before the 2015 summit, global emissions were on course to push temperatures up by 3.5°C by 2100, according to the Climate Action Tracker, a nonprofit science consortium. Now, that trajectory has flattened to 2.9°C.

Technological, economic, and political changes have all helped, says Bill Hare, a physicist and CEO of Climate Analytics, a nonprofit. The cost of renewable energy technologies, such as solar power, has plummeted. Economic growth has slowed. Regulations, spurred in part by the Paris pact, have begun to bite. In Europe, emissions of warming gases fell 23% below 1990 levels by 2018.

But less encouraging developments have slowed further progress. Deforestation has soared in the Amazon in recent years, releasing ample amounts of carbon into the atmosphere. Russia, a major polluter, has made few moves to reduce emissions. President Donald Trump withdrew the United States from the Paris deal with no real penalties. (President-elect Joe Biden plans to rejoin it.) And many U.S. states that rushed to make up for Trump's withdrawal by launching a state-level version of the Paris goals are also falling short, according to a new analysis by the Environmental Defense Fund (EDF). Under former President Barack Obama the United States had promised cuts of between 26% and 28% from 2005 levels by 2025. The states, however, will likely cut emissions by just 18%. “It's easier to speak rhetorically about the importance of climate change than it is to do the hard work,” says Pam Kiely, EDF's senior director of regulatory strategy.

GRAPHICS: (TOP TO BOTTOM) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION; CLIMATE ACTION TRACKER, ADAPTED BY V. ALTOUNIAN/SCIENCE

The mix of contrasting trends has meant the progress enabled so far by the Paris agreement has been “very incremental,” Hare says. “What needs to happen in the next few years … is something much more transformational.”

To celebrate the Paris pact's fifth anniversary, some nations signaled that they are ready to do more. At a 12 December virtual summit attended by more than 70 nations, Chinese President Xi Jinping said that by 2030 his country—the world's largest greenhouse gas emitter—would cut emissions associated with each unit of economic productivity by 65%. That's on top of China's commitment earlier this year to reduce its net carbon emissions to zero by 2060.

Other nations have embraced a more ambitious net zero target by 2050, including Canada, South Korea, the European Union, and the United Kingdom. And EU leaders want to cut emissions by 55% compared with 1990 levels by 2030.

Climate advocates, however, say nations are still not aggressive enough. Some note, for example, that the world's 20 richest countries have earmarked $12 trillion to address the economic disruption caused by COVID-19, but just one-quarter of the countries are dedicating money to projects that would reduce carbon emissions, according to a new report from the United Nations Environment Programme. “We've never had $10 [trillion] to $20 trillion … to reboot the world economy,” said Andrew Steer, president of the World Resources Institute. “If we invest that in yesterday's economy we are basically committing a mortal sin for our grandchildren.”

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