There are many people in the scientific and political community that deny climate change. There is scientific evidence on both sides, and the science against climate change is more compelling. There's nothing wrong with a politician expressing a personal opinion, even if other people are yelling louder on the same topic.
I would never vote for a politician who denies climate change, as the evidence strongly suggests that climate change is a real phenomenon. Numerous scientists have written papers and given presentations that describe rising temperatures, stronger storms and melting ice in the polar regions of the world. Climate change has ramifications for the safety of coastal communities and for the success of agriculture throughout a country. Politicians who ignore the strong evidence of climate change may play a role in climate change becoming an even more severe problem in the future.
In order to be a politician you must know the facts whether you want to accept them or not. You must have clear solutions to make sure that the problems we have in this country get solved and that we are doing all we can to make this a better place to live not just for ourselves but the future generations that will come after us.
I'm not sure who is worse, the ones that "honestly" don't believe the science, or the ones that do, but still don't want to take action, lest it upset their corporate overlords. If there is a test required before a person is allowed to drive a car, then one should be administered before people are allowed to run a country.