Big oil companies like Exxon Mobil, and Koch Industries have spent millions (npr.org) on spreading disinformation and fighting the science of climate science. Internally they acknowledged that it would harm the environment, between their scientists and executives (npr.org). One of the chief ways they did this was by politicizing the issue. By doing so they made it much harder to pass any policy about climate change. This has set back U.S. climate policy by decades and caused preventable and possibly irreversible damage to the environment.
This is, obviously, a huge problem. If climate change isn't at least slowed, it will cause irreversible and extreme damage to the environment. If this happens we will be in grave danger. I feel that, although this is a political issue now, it never should have been a political issue. Climate change is real. Climate change is anthropogenic. Climate change is a threat. Climate change is causing irreversible damage to the environment and there is no way to stop it without people believing these things.