The United States is back in the Paris climate accord, but the depth of its commitment will become clear only in the next two weeks, when President Joe Biden unveils the details of the nation’s pledge for reducing greenhouse gas pollution.

President Barack Obama pledged that the United States would cut emissions 26 to 28 percent by 2025, a goal the nation is not quite on track to meet. But environmental advocates are pushing for Biden to set a goal of at least a 50 percent cut in U.S. emissions by 2030, based on a slew of recent studies, including research by the United Nations and the National Academies of Science, showing that a 50 percent target is both necessary and achievable. On Tuesday, a coalition of hundreds of businesses, including Walmart, Apple, Microsoft, Verizon and Unilever, sent a letter to the White House, joining in the call for a 50 percent goal.

Only by doubling the original U.S. commitment under the Paris accord, they argue in the letter, will the world’s largest economy and historic contributor to carbon pollution be in a position to persuade other nations to join in the action necessary to hold global warming below 1.5 degrees Celsius.

“To restore the standing of the U.S. as a global leader, we need to address the climate crisis at the scale and pace it demands,” said the letter from the We Mean Business coalition, organized by the investor activist group Ceres.

Scientists and economists have charted a number of different paths that would allow the U.S. to cut greenhouse gas emissions in half in less than a decade, but all of them entail dramatic changes. At least half of new passenger vehicles purchased in 2030 would be electric. Coal-fired electricity would essentially become a thing of the past and carbon capture and storage plants would become common at the remaining fossil fuel plants, which would be mostly natural gas-fired. Millions of buildings would be retrofitted to use less energy. 

Critics of the idea warn that there are plenty of obstacles in the real world that could complicate an overhaul of the energy system like the one envisioned by academics.

The push back from Republicans in Congress over Biden’s infrastructure plan made clear the resistance he is certain to face in any effort to implement such a transformation. But environmental advocates argue that the rapid fall in the cost of renewable energy and battery technologies make a high target economically feasible. And the broadening of the climate movement—including support for a strong goal from businesses—make it possible for Biden to be bold when he delivers the U.S. pledge, an announcement expected at or before the April 22, virtual Earth Day climate summit of 40 nations, organized by the White House.

“This target really is serving as the North Star for domestic policy,” said Dan Lashof, director of the World Resources Institute. Noting all the climate initiatives that Biden has announced so far—executive orders, the infrastructure proposal, his planned regulatory actions—Lashof said, “This is a moment to say, ‘Here is what we aim all that to add up to.'”

And after the four-year U.S. retreat on climate led by President Donald Trump, experts in international policy argue that, unless Biden sets the bar high, the United States will lack credibility on the world stage to play the kind of leadership role he has promised. 

“Anything under the 50 percent would be severely unequivalent” to the job of addressing climate change, said Jennifer Tollmann, senior policy advisor with E3G, an international climate and energy think tank.

‘A Red Alert’

The climate deal that 197 nations struck in Paris in 2015 involved no legally binding targets or timetables, but included a process for nations to ratchet up their pledges every five years. It was a way to break a stalemate that had stymied negotiations for the previous quarter century, and to bring all nations—rich and poor—to the table to make differing commitments. In theory, the ambition in those commitments would increase as clean energy became more affordable.

But fewer than half the parties to the Paris accord submitted new, more ambitious pledges by the end of 2020, as the treaty envisioned; the 75 parties that did make new commitments accounted for less than 30 percent of global emissions. Major emitters that have not offered their new pledges yet include, in addition to the United States, China, Canada and India. Combined, the pledges offered so far would reduce global emissions by less than 1 percent by 2050, the United Nations Environment Programme calculated in a February report. The Intergovernmental Panel on Climate Change has estimated that to get to net-zero emissions by 2050, global emissions must be reduced 45 percent from 2010 levels by 2030.

United Nations Secretary-General António Guterres said the report was “a red alert” for the planet. “Governments are nowhere close to the level of ambition needed to limit climate change to 1.5 degrees and meet the goals of the Paris Agreement,” he said, calling for more ambitious targets before the next global climate talks, currently scheduled for November in Glasgow.

Liane Schalatek, in the Washington, D.C. office of the international Heinrich Böll Foundation, a nonprofit green policy think tank, wrote recently that nations must triple their reduction efforts in order to still reach the Paris target. “This makes the pressure for a correspondingly ambitious and visionary U.S. contribution even greater,” she wrote.

Biden signaled on his first day in office that he wanted the United States to play a leading role in getting the Paris process back on track, announcing the livestreamed Earth Day summit. The White House has invited leaders of 40 nations to participate, not only the 17 or so major economies that cause the most global warming pollution, but smaller nations that are the most vulnerable to warming, like Bangladesh, Gabon, the Marshall Islands and Vietnam.

The commitment to action that Biden makes in the run-up to the summit is a more significant moment for global climate politics than even the United States rejoining the Paris accord, said Nathan Hultman, founder and director of the Center for Global Sustainability at the University of Maryland.

“Paris itself is just an organizing framework. What matters is what the countries actually do,” said Hultman, who served in the Obama White House and helped develop the initial U.S. pledge under the accord. “Despite the fact that at the federal level the United States has not been leading in the last four years, it remains a country that many countries look to, to kind of calibrate how ambitious they should be.

“If the U.S. steps back, everybody steps back,” he said. “If the U.S. steps forward, everybody’s going to be looking and saying, OK, I think we’re back in the game now.'”

But in the view of Hultman and many others, that means going far beyond Obama’s initial Paris  pledge to reduce greenhouse gas emissions by 26 to 28 percent from 2005 levels by 2025. He and his colleagues at the University of Maryland have produced one of a slew of new analyses showing how the United States, which has been using 2005 as its baseline year, can get to a 50 percent reduction in greenhouse gas emissions by 2030. (That is roughly equivalent to the 45 percent from 2010 levels that the IPCC has recommended.)

“At this moment, it’s not enough to just say, we’re back,” said Rachel Cleetus, policy director for the climate and energy program at the Union of Concerned Scientists. “We have to come back with a very bold commitment to climate action.”

There is broad consensus among the analysts—including the National Academies scientists at the University of California, Berkeley and Princeton, economists at the University of Chicago and environmental groups like Environmental Defense Fund and the Natural Resources Defense Council—that the biggest reason that Biden can make a 50 percent pledge is the plummeting price of renewable energy.

An Uneven Playing Field For Renewables

The cost of wind power is down 70 percent; solar energy down 90 percent since the start of the Obama administration, according to the finance firm Lazard’s. As producers turned to cheaper, cleaner power, renewable energy consumption in the United States surpassed consumption of coal last year for the first time since the start of the Industrial Revolution, according to the U.S. Energy Information Administration. In 2020, 41 percent of U.S. electricity came from carbon-free sources, about half of that from renewables like wind and solar and half from nuclear energy.

But to slash greenhouse gas emissions throughout the U.S. economy by 50 percent, the reduction from electric power plants will have to be much greater, around 80 percent by 2030, according to most analyses. That would put the nation in a better position to meet Biden’s goal of eliminating 100 percent of carbon emissions from electric power by 2035.

Without a major policy push, however, climate progress in the U.S. power sector is on track to stall out, with coal and natural gas continuing to battle for market shares in the years to come, forecasters say. That’s because the nation’s power system is designed for centralized fossil fuel power, not renewable energy, and the switch to cleaner power entails costs like new distribution lines, large-scale batteries and other storage options. Coal and natural gas can continue to win out in the competition with wind and solar as long as the market continues to ignore the potential expense of climate disruption or the health impact of pollution. 

“Low carbon technologies face an uneven playing field in the United States due to competition from fossil fuel sources that do not pay for the costs that their emissions impose on society,” wrote Michael Greenstone, director of the Energy Policy Institute at the University of Chicago, in his group’s roadmap for decarbonizing the United States.

Greenstone, former chief economist in the Obama White House, argued that putting a price on carbon—either through a tax or a cap on emissions—would be the most cost-efficient way to level the playing field for clean energy. But acknowledging the difficult politics of pricing carbon, he and his team laid out a proposal for a national Clean Energy Standard, an idea that Biden already has embraced in his infrastructure plan. Such a standard would be similar to the Renewable Portfolio Standards that are already in place in 37 states, mandating that utilities increase energy from clean sources over time. 

The electric power industry is split on how high a bar the U.S. should set in its Paris pledge. Exelon and Pacific Gas & Electric, which have no remaining coal plants, signed on to the business letter endorsing a U.S. Paris goal of 50 percent by 2030. Most analysts agree that such a goal would require the retirement of most remaining coal plants, and the National Academies report concluded that 10 to 30 percent of natural gas plants would need to close or be equipped with carbon capture and storage systems, a technology not currently in operation at any U.S. power plant.

Companies that still have coal fleets have been mostly silent about the Paris goals, but their own decarbonization plans show them planning a less dramatic trajectory than the Biden administration has envisioned. American Electric Power of Columbus, Ohio, for instance, has a goal to reduce its carbon emissions 70 percent by 2030 from a 2000 baseline, which was the year the company’s emissions peaked. But that means a slow decline over the next decade for the utility, which already has cut CO2 emissions 65 percent in CO2 output. American Electric Power’s long-term goal is an 80 percent reduction by 2050, not in line with the complete elimination of such emissions that the IPCC says will be necessary to hold warming below 1.5 degrees Celsius.

“The world has changed a lot in the last 10 years, and companies are not only setting goals on decarbonization, but they’re putting in place plans to achieve those goals,” said Jeff Holmstead, a partner at the law firm Bracewell LLC who represents industry clients. “None of them that I’m aware of believe they can get to zero emissions by 2035, much less by 2030.”

Holmstead, who was a top Environmental Protection Agency official under President George W. Bush, said that there are practical limitations to rapid progress in the industry, for example, how long it takes to get approval for long-distance power transmission lines.

“It’s one thing for an academic to write a paper saying, in theory, here’s how we can get to carbon neutral by 2035,” Holmstead said. “But that doesn’t take into account all the process and the transactions involved. In the real world, I just don’t think it’s possible.”

But the Biden administration, which does have plans to speed approval of transmission lines, has given every indication it plans to articulate an aggressive Paris goal—with a focus on driving down fossil fuel emissions in electric power.

“The scientists tell us it just doesn’t work to issue a mid-century goal without reducing sufficiently between now and 2030,” said John Kerry, White House special envoy for climate change at a virtual ministerial meeting of G20 countries on climate change in March. “Without that and without a miracle, it’s as highly improbable as it is highly implausible that you could ever get to 2050 net-zero in a way any country would ever choose.”

He added, “Our words must be backed up by near-term action, including the transition away from unabated coal.”

Bob Berwyn contributed reporting.