barbara basil -- barbara wesel is in brussels. carl-friedrich it's in the studio, an advisor to the united nations on global warming. carl-friedrich: i think trump tried to embed his withdrawal from the climate agreement into basically promoting his viewpoint on all of this and the wider issues. some of these numbers are certainly questionable. it's hard to say where he's been drawing them from. there are several elements to it which have -- which are really important. the most important one is his perception of fairness in the climate debate. climate change is driven by greenhouse gases. co2 simply stays in the atmosphere for a very long time. every emsi -- every emission -- climate change that you have today is caused by emissions in the past. it's already occurring today. there is no country in the world with a bigger responsibility to the u.s.. eventually, fighting climate change in a fair and equitable fashion means that countries that have a big historic burden need to go ahead, move ahead, and basically achieve strong reduc