I think you'll find that as soon as researchers began looking into the harmful effects of smoking, the link to cancer quickly became the scientific consensus. It did not become the popular consensus for decades because of the indefatigable opposition campaign funded by the tobacco companies.

A good history of all this is here: https://pubmed.ncbi.nlm.nih.gov/22345227/

Imagine if a company had prohibited tobacco advertising that asserted smoking was healthy. That's the parallel here.

I am not disagreeing with your points. I was just trying to point out the consensus can be wrong and the consensus can change.

The problem I have with this is they will almost certainly allow things that contradict the consensus. Let's say the consensus is like 2C increase in 50 years. If somebody says it will actually be 3C they would be contradicting the consensus but probably would be allowed the ad. If somebody says it will only increase 1C they would probably not be able to sell an ad.

Yeah, consensus changes. Especially when new evidence and new ideas arise. That shows that scientific consensus is working.

If the scientific consensus threatens assets and income of powerful industries they run massive lobbying and ad campaigns against it and try to interfere with the scientific process itself by funding biased studies.

Pretending like the people that exaggerate the effect of climate change are a comparable issue is dishonest and not backed by facts. Classic false symmetry fallacy.

Also, the scientific consensus is conditional: If we emit like this, then that will happen. The IPCC report doesn't predict a certain amount of warming.

> Don't forget that the consensus used to be that tobacco was harmless

No? Tobacco companies themselves knew tobacco wasn't harmless. Just like oil companies have known for almost a century that humans were causing drastic climate change due to CO2.

I don't think tobacco companies knew 100 years ago. The data didn't really become conclusive until something like the 50s. There absolutely was a consensus in the 20s and 30s that cigarettes were not harmful.