Joe Biden faces major test building US credibility at climate summit

President will unveil new emissions reduction target while much will hinge upon cooperation between China and US

Joe Biden's desire to re-establish US leadership on the climate crisis will face a severe test this week at a summit the president hopes will rebuild American credibility and kickstart a spluttering international effort to stave off the effects of global heating.

Biden has invited 40 world leaders to a two-day virtual gathering starting on Earth Day, Thursday, as the opening salvo in negotiations leading to crunch United Nations talks in Scotland later this year. Scientists say the world is severely lagging in tackling the climate crisis and its heatwaves, storms and floods, with planet-heating emissions set to roar back following a dip due to coronavirus shutdowns.