This story was originally published by the Guardian and is reproduced here as part of the Climate Desk collaboration. The rapidly shrinking window of opportunity for the US to pass significant climate legislation will have mortal, as well as political, stakes. Millions of lives around the world will be saved, or lost, depending on whether America manages to propel itself towards a future without planet-heating emissions. For the first time, researchers have calculated exactly how many people the US could save by acting on the climate crisis.