w.'s environment desk. joe biden is hosting 40 world leaders at a virtual summits tackle climate change today after abandoning international climate efforts what does the u.s. need to do now the u.s. has one of the world's biggest historical polluters and to put more carbon dioxide into the atmosphere than any other economy in the world and it's expected that joe biden will announce today a new target of cutting and cutting emissions by 50 percent by the end of the decade compared to the levels in 2005 now that more ambitious than the target would put in place under obama president the former president obama but i mean a lot of countries are also quite reluctant to just accept promises from the u.s. at face value the previous president trump the u.s. withdrew from the powers agreement and the chinese foreign ministry just last week described the return actually of as a true schoolchild returning to class by them will have a lot cut out to actually convince countries that these pledges really do mean somethi