The presidents of China and Russia have agreed to work with the U.S. to reduce greenhouse gas emissions.
Xi Jinping and Vladimir Putin put recent spats with the U.S. behind them to seek consensus during the climate meeting.
Xi said in a speech China would cooperate with the U.S. in finding efficient ways to cut carbon emissions. China is the world's biggest carbon emitter followed by the U.S. Russia is considered the fourth largest.
Putin, whose administration is at odds with the U.S. as a result of tensions in Ukraine and recent sanctions imposed by the administration of President Joe Biden, said Russia "is genuinely interested in galvanizing international cooperation."
Others who promised cooperation in cutting emissions by up to 52% within the next decade included Britain and Germany.
While the rare U.S.-China-Russia joint climate change effort raised hopes for an international response, Biden's ambitious target has been met with skepticism.
Biden's climate change envoy John Kerry said the new goal is indeed "ambitious but appropriate and achievable."
However, Senate Republican leader Mitch McConnell thinks otherwise. McConnell said the target would bring about "maximum pain for American citizens" because of its cost.
Biden's plan includes setting aside an estimated $5.7 billion a year by 2024. The administration said it would cooperate with the U.S. Congress on the goals.
Climate activist Greta Thunberg, during a U.S. congressional hearing the day of Biden's climate summit, said international climate targets were "insufficient."
Thunberg, who called the U.S. the "biggest emitter in history," said current climate targets weren't enough to cut emissions quickly. She challenged leaders to stop making "vague, distant" plans.
"How long do you honestly believe people in power, like you, will continue to get away with it?" the 18-year-old Swedish activist said.
Thunberg has questioned the sincerity of countries that have promised to meet zero emissions. She said the problem must be treated "like a crisis" and taken more seriously by world leaders and companies.
