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Traffic-free roads, plane-free skies and widespread brick-and-mortar closings have made the planet a beneficiary of the coronavirus pandemic — but only in the short term.

Li Shuo, senior climate and energy policy officer at Greenpeace in Beijing, said it's not time to "pop the champagne corks" just yet.

"It's hardly a sustainable way to reduce emissions," he said.

Many climate experts spotlighted 2020 as a critical year to take decisive action to limit the worst impacts of global warming. The year started with international attention on catastrophic wildfires and floods.

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The pandemic has overshadowed those issues — but with an environmental silver lining. The sharp reductions documented in carbon emissions and air pollution caused by coronavirus-related lockdowns have offered a sort of preview of the kind of improvements that can be made when drastic action is taken.

But the changes could easily be wiped out by efforts to quickly ramp up economies, including governments around the world that may be more willing to relax regulations to jump-start companies.

Despite an estimate showing that China — the world's biggest polluter — emitted 25 percent less carbon than in the same four-week period the previous year, Shuo remains skeptical about any lasting changes. He said he's worried that efforts to reignite China's economy might end up making the coronavirus epidemic a step backward for climate efforts.

Average nitrogen dioxide concentrations from air pollution across France in March 2019, left, and March 14 to 25, 2020, as mapped by the Copernicus Sentinel-5P satellite, a reduction that the European Space Agency says is due to the strict quarantine measures during the coronavirus outbreak. European Space Agency / via Reuters

That's because if history is anything to go by, China might not take the greenest option.

Lauri Myllyvirta, lead analyst at the Centre for Research on Energy and Clean Air, based in Finland, said China responded to the 2008 financial crisis with the "biggest, dirtiest stimulus program in the history of mankind."

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"It meant that for the following three years there was rapid growth in CO2 emissions, and we can now say with quite a bit of certainty that the overall impact was to nudge China on a more carbon-intensive, fossil fuel-intensive economy path," Myllyvirta said.

How other nations handle their responses to the economic shock will also be critical.

There are some glimmers of hope that ambitious climate action could play a part. European Union leaders have said the recently announced Green Deal must be at the heart of an "intelligent recovery." In spite of pressure to soften its green ambitions because of the pandemic, the EU has begun a consultation on tightening its carbon reduction targets by 2030.

Things look less promising in the U.S. Last week, the Environmental Protection Agency confirmed that the Trump administration had relaxed enforcement of regulations to help polluting industries deal with the pandemic. Gina McCarthy, who directed the EPA in the administration of President Barack Obama, called the announcement "a license to pollute."

Meanwhile, some industries in the U.S. and Europe are pushing to relax other regulations.

The plastics industry, recently on its back foot over ocean pollution fears, has worked to turn the tide on plastic bag bans.

Although the science is far from clear, plastic makers have long argued that single-use plastics are safer and more sanitary than reusable alternatives. Plastics Industry Association CEO Tony Radosewski recently stressed the need for more single-use plastics to combat the spread of the virus in a letter March 18 to the U.S. Department of Health and Human Services.

And it seems that many lawmakers are listening.

Plastic bag restrictions have been lifted across the country. In New York and Maine, recently introduced bans have been delayed. In Connecticut, plastic bag fees have been removed, while in New Hampshire, Gov. Chris Sununu prohibited shoppers from bringing reusable bags and ordered stores to make disposable bags available.

Likewise, the crisis has been a boon for the auto industry, with the Trump administration seizing the moment to fulfill a campaign promise to weaken Obama-era emissions standards. Automakers in the EU are also lobbying for a delay in tightening emissions restrictions because of the crisis. And in China, plans for tougher standards look likely to be delayed to help struggling automakers.

Airlines including Delta and JetBlue started off the year promising carbon offsets amid a growing culture of "flight shaming." The airline industry is also lobbying for government bailouts and regulation relief.

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With governments focused on the crisis, there are also fears that the diplomatic push to refocus global efforts on reducing emissions could slip.

The United Nations' COP 26 climate conference, scheduled to be held in Glasgow, Scotland, in November, has been postponed until 2021. It had been hailed as the most important climate gathering since the Paris climate accord was signed in 2015. Under that agreement, countries are due to come back to the table with new pledges to limit warming to the agreed-upon level of "well below 2 degrees" Celsius (3.6 degrees Fahrenheit) and ideally below 1.5 degrees.

It's "abundantly clear that the countries of the world are falling short of the goals of the Paris agreement," said Dr. Simon Evans, deputy editor of Carbon Brief, a climate science website.

"Current pledges have the world on track for warming of about 3 degrees" Celsius, he added.

Environmentalists have already raised concerns after Japan — the world's fifth-biggest emitter — became the first G7 country to announce its new targets. The plan, however, would simply maintain the country's existing emission reduction pledges. The World Resources Institute, a research nonprofit based in Washington, criticized the approach for falling "woefully short."

A successful outcome in Glasgow, therefore, looks likely to require extensive preparatory work and diplomacy. As Evans said, the Paris agreement was "built on years of diplomatic efforts on the part of the French government and the whole French diplomatic service over the course of about three years."

Although the postponement of the climate conference does provide welcome extra time for work toward a successful summit, he argued that it is "inevitable that countries' preparatory work toward their new pledges" will have been affected.

So while the world looks likely to emerge from the pandemic — at least temporarily — with cleaner air and lower emissions, "any positive environmental impact" from the crisis relies on our "changing our production and consumption habits towards cleaner and greener," Inger Andersen, executive director of the U.N. Environment Program, wrote this week.

"Only long-term systemic shifts will change the trajectory of CO2 levels in the atmosphere," she said.