The United States and China, rivals on the world stage and also the two biggest economies and the two biggest emitters of greenhouse gases made some big climate promises at the UN this week.

Chinese president Xi Jinping promised China will stop building coal-fired power plants abroad, a big deal because it is the world’s major funder of coal projects.

U.S. President Joe Biden promised he will seek Congressional support to increase climate aid for developing nations, and this is key because of mounting anger at the rich nations’ failure to meet commitments to help poorer countries deal with climate change.

Big promises, but we continue to get a lot more promise than action on the climate front. Will this be any different?

China is a massive user of coal, consuming well over four times as much as India, the second largest consumer, and Xi said nothing about slowing down or stopping coal plant construction at home.

As for American promises, Biden’s Democrats need the vote of West Virginia Senator Joe Manchin, who has close political and financial ties to the fossil fuel industry, to meet their climate goals. His state ranks second in coal production, seventh in natural gas output, and he owns stock in a coal brokerage firm. He also just happens to head the Senate Committee on Energy and Natural Resources.

So what are these big promises worth? Playing the eternal optimist, I will expect them to be fully met. But I won’t uncross my fingers. And we will, of course, need much much more from both parties.