字幕表 動画を再生する 英語字幕をプリント After four years of environmental rollbacks under the Trump administration, the US is back in the global charge to tackle climate change. President Joe Biden has ambitious goals. By the end of the decade, he wants to cut US greenhouse gas emissions to half of what they were in 2005, and set the nation on a path to net zero by 2050. No easy feat for a country that spews more than 6.5bn tonnes of carbon dioxide equivalents into the atmosphere each year, or around 15 per cent of the global total. Analysts say the quickest way to cut US emissions is to decarbonise electricity, which accounts for around a quarter of the problem. About 60 per cent of America's power generation comes from burning fossil fuels, mostly coal and natural gas. The president wants tax breaks to reward greater investment in renewables like wind and solar. And a proposed “Clean Electricity Standard” would force suppliers to be 80 per cent carbon-free by 2030, before the complete removal of emissions from the grid by 2035. Transport is another big polluter. The president wants to encourage more drivers to go electric, with financial incentives and by expanding the number of charging points from 43,000 to half a million nationwide. Sales of plug-in cars capable of running on electricity alone peaked at over 360,000 in 2018. The production of some popular models ceased in following years, coinciding with a dip in new buyers. Biden has framed his automotive push as a question of winning the market back from China, the world leader in electric vehicle manufacture. Tackling the third major problem sector, carbon intensive industry like cement and steel, will not be simple. There is hope that potential solutions like clean hydrogen or carbon capture can play a significant role, but neither is currently developed at a commercial scale. Even the president's climate envoy John Kerry has suggested that half of the required reductions would have to come from technologies that do not yet exist. And then there is the political problem. Biden's Democratic party has only a narrow majority in both the House of Representatives and the Senate. In the House, Democrats cling to a slim lead with 220 seats, compared to the 211 in Republican hands, while the Senate is split 50-50 with the vice-president holding the deciding vote. To get far-reaching legislation through the upper house he will also need the backing of 10 Republicans. The president may have big plans to create a net zero United States, but getting Congress on board with the huge changes necessary to get there will be tough.