This Earth Day, April 22, leaders representing some of the world’s biggest economies—and, thus, biggest polluters—will gather virtually for another meeting on climate change. The gathering, which the White House has dubbed the Leaders Summit on Climate, is President Joe Biden’s chance to rebuild the United States’ bruised credibility on climate action after four years of isolationism.

The summit will bring together the leaders of 17 countries responsible for approximately 80 percent of global emissions as well as the heads of other nations that are demonstrating strong climate leadership or are especially vulnerable to the impacts of climate change, such as Bangladesh and the Marshall Islands. Participating nations are expected to discuss a range of topics, including how to help vulnerable countries cope with climate disruption; the economic benefits of climate action, with an emphasis on job creation; and the role of “nature-based” solutions in achieving emissions reduction.

Sometime this week before the summit begins, the Biden administration is expected to announce “an ambitious 2030 emissions target,” known in United Nations–speak as a Nationally Determined Contribution, or NDC. In his invitation, Biden urged the other leaders attending the summit to do the same. According to The New York Times, Biden is nearing emissions reduction agreements with Japan, South Korea, and Canada. And just last week, John Kerry, Biden’s global climate envoy, traveled to Shanghai to try to get new emissions-reductions pledges from China, the world’s biggest emitter. 

Under the 2015 Paris Agreement, almost every country on Earth pledged to hold the increase in average global temperature to well below 2 degrees Celsius (3.6 degrees F)—and to try to hold it to 1.5 degrees Celsius (or 2.7 degrees F), the threshold scientists have established for staving off the worst effects of climate change. The summit’s stated goal is to “catalyze efforts that keep that 1.5-degree goal within reach,” according to a White House statement. The Paris Agreement doesn’t do much other than coordinate actions on climate that are rooted in domestic decisions. Its most significant tool is the NDC, which signatories of the agreement promised they would renew every five years. 

The Paris Agreement has been described as a “potluck” of a pact, where every country is invited to bring its own emissions-reduction target to the table or, if they don’t, run the risk of looking like a freeloader. Given the world’s failure to take the threat of climate change seriously, a potluck seems too forgiving a metaphor. Before Paris, the world’s biggest economies were not a group of environmentally conscious septuagenarians headed to a Bread Not Bombs dinner. They were more like high school sophomores preparing for a group presentation. It’s all about the peer pressure. No one wants to be the jerk who shows up empty-handed. 

Sticking with the high-schooler metaphor, the United States is like the most popular—if not necessarily the most accomplished—student in the class. If it doesn’t show up, the group is bound to fail. But if it does, it can nudge everyone else toward a successful outcome. This is one reason why a new, ambitious NDC is essential to reestablish US credibility on climate. “The expectations for the Biden administration are very high,” said Samantha Gross, director of the Energy Security and Climate Initiative at the Brookings Institution. “An ambitious NDC will be helpful from that peer pressure aspect.”

Seven years ago, President Barack Obama announced the United States’ first NDC in a joint conference with Chinese president Xi Jinping in Beijing. Obama pledged to put the United States on a path toward reducing emissions by 26 to 28 percent below 2005 levels by 2025. 

Whether the United States will meet Obama’s 2025 target remains to be seen. A recent report on US greenhouse gas emissions from the Rhodium Group found mixed results. Last year, US emissions dropped more than 10 percent—the single largest drop in the post-World War II era and the first time that emissions dipped below 1990 levels. The United States even exceeded its 2020 Copenhagen Accord target of a 17 percent reduction below 2005 levels. But this progress is unlikely to last. The 2020 emissions reduction wasn’t the result of a rapid and thorough economic transformation, but of the economic destruction and human suffering caused by the COVID-19 pandemic.

Climate-action advocates hope Biden will nearly double the Obama-era NDC. In a recent working paper, Nate Hultman, who helped develop the first US emissions-reduction target as a member of the Council on Environmental Quality for the Obama White House, argued that a comprehensive federal effort across all sectors—particularly electricity and transportation—could reduce emissions by 50 percent below 2005 levels by 2030. Last week, the chief executive officers of more than 300 of the country’s largest businesses—including Google, McDonald’s, and Walmart—sent a letter to Biden calling for reductions of that scale.

“The United States should try to achieve the highest ambition possible while still putting forward a plausible pathway to success,” said Hultman, now director of the Center for Global Sustainability at the University of Maryland. “The right balance of those two is around a 50 percent reduction by 2030. More would be welcome and valuable. Anything less would be disappointing.”

Hultman said the United States has multiple pathways to achieve a 50 percent reduction in greenhouse gas emissions by 2030—including the sort of “investment-led” legislation that makes up the bulk of Biden’s new infrastructure and clean energy plan (and that, importantly, Democrats in Congress can pass on their own, through budget reconciliation). Achieving any more than 50 percent, though, would be hard. No matter which path you take or policy levers you pull, there is only so much of the electricity sector that can be decarbonized and so many gas-guzzlers that can be electrified in nine years. 

All of this is to say that the window for meeting this target is closing fast. The longer we wait, the farther real progress on climate action gets pushed out of reach. 

“I’m less interested in the top-line number of the new US nationally determined contribution. What I really want to do is turn to the next page and read about how we plan on getting there,” said Gross. “Where the rubber meets the road is not the promises countries make. It’s the policies they put forward to fulfill them.”