to well below two celsius and to aim for 1.5. that's the threshold scientists agree beyond which the most dangerous impacts of global warming play out. so now it comes down to here in glasgow. to keep that 1.5 celsius target alive, emissions need to halve within the next decade, and to reach net zero, where the world is taking out as much carbon from the atmosphere as it's putting into it, by the middle of the century. so the 200 countries being represented here at cop26 are being asked for their specific plans to meet that goal. the success of this conference will be based partly on countries' willingness to outdo each other when it comes to emission reduction. the uk's net zero strategy has been widely praised. the government has promised to fully decarbonise our electricity supply by 2035, and to phase out the sale of petrol and diesel cars by 2030. but some countries have much more ambitious goals. costa rica, a country that has committed to phasing out