Stephen Hawking and Brian Cox are not in the climate change business but they are pretty sure man made climate change is a fact. I'll take either of them against Nigel Lawson any day on matters of science.
Most of us have heard the tale of 'The Emperors New Clothes' where despite the fact the guy was as nekked as the day he was born everyone agreed his new clothes were very good indeed (because they had been told by the makers that stupid people would not be able to see the clothes) - this caries on until a child (who was not in on the plot and did not tell the Emperor what he thought he wanted to hear) blurted out 'but he hasn't go any clothes on' after which everyone had to agree with the child and the whole scam was rumbled.
https://www.phrases.org.uk/meanings/the-emperors-new-clothes.htmlCo2 theory suited governments, who could see Dollar signs from all the (easily) levied 'Carbon Taxes' which could swell their coffers without really doing much except to instruct industry to 'reduce your carbon footprint' , as time went on the Global warming / climates change (changed the name when they realised that the last 10 years after 1998 had actually seen a drop in temperature, and they wanted to cover all the bases and convince people that it was not only global warming, but it was gonna make the climate 'unstable' and basically it could warm up or cool down and they would still appear to be right). Out of the MMGW / CC theory grew a worldwide movement dedicated to spreading the message (and if they could make a career and governments could make loads of easy money, where was the downside).
The same 'Emperors new clothes' works in all walks of life, some call it peer pressure, groupthink etc. but it all boils down to the fact that no-one wants to appear out of line or stupid. This works extremely well in the 'modern art' world, (surely the biggest scam of all) with many documents cases of getting kids to splash paint on a canvas, signing it with a well known artists name and seeing the 'experts' fall over themselves to see the 'meaning' in the splashes of paint, and guess what these people don't even have the honesty to be embarrassed when the fraud is pointed out.
https://en.wikipedia.org/wiki/GroupthinkStephen Hawkings and Brian Cox may be clever people, but at the end of the day humans can only work to the limit of present knowledge, and even people like those can be influenced by peer pressure and groupthink.
The sun only has to sneeze and we catch a cold, there has been a lot of worry lately about increasing sun activity, solar storms etc. which have the power to take out our precious computers (look out Autonomous vehicles) and electrical supplies (happened in Canada a few years ago).
Ice sheets have actually been increasing lately, and they reckon any melting due to soot and black particulates (diesel) landing on ice surface and absorbing suns heat.