Michael Mann described the 6 stages of climate denial in 2013. At the time the hard core deniers were still stage 1, nowadays they mostly seem to have moved to at least stage 3, and many of the politicians that are obstructing are stuck in stage 5 or 6. I hear a lot of category 6 denial from the politicians in my own country.
1. CO2 is not actually increasing.
2. Even if it is, the increase has no impact on the climate since there is no convincing evidence of warming.
3. Even if there is warming, it is due to natural causes.
4. Even if the warming cannot be explained by natural causes, the human impact is small, and the impact of continued greenhouse gas emissions will be minor.
5. Even if the current and future projected human effects on Earth's climate are not negligible, the changes are generally going to be good for us.
6. Whether or not the changes are going to be good for us, humans are very adept at adapting to changes; besides, it's too late to do anything about it, and/or a technological fix is bound to come along when we really need it.