The US aims to cut greenhouse gas emissions by 2030 as part of its new commitment to the Paris climate agreement,

President Joe Biden made the pledge, called the “nationally determined contribution,” while speaking at a two-day virtual climate summit attended by dozens of world leaders Thursday morning. Biden rejoined the 2015 climate pact in February, reversing a decision by President Donald Trump to withdraw the U.S. from the global coalition to curb carbon emissions.

“These steps will set America on a path of net zero emissions economy by no later than 2050,” Biden said in remarks from the White House. “But the truth is, America represents less than 50 percent of the world’s emissions. No nation can solve this crisis on our own, as I know you all fully understand.”

The president emphasized that scientists say the current decade will be decisive for addressing the climate crisis.

“This is the decade we must make decisions that will avoid the worst consequences of the climate crisis,” Biden said, adding, “We can’t resign ourselves to that future. We have to take action on this, and this summit is our first step on the road we’ll travel together.”

U.S. emissions of heat-trapping greenhouse gases plunged last year, but that was an anomaly owing to the corona virus pandemic, which put the brakes on large segments of the economy. As the country rebounds, emissions are expected to rise once again, and the Biden administration is racing to find ways to put the U.S. on track to meet even more ambitious targets that scientists say are needed to avert the worst effects of global warming.