The reason Republicans don’t believe that human activity is linked to climate change is because many of their major donors are the ones from the fossil fuel companies. If they were to say that human activity is linked to climate change, they would immediately lose millions of dollars in campaign donations.
Deep down, they know it’s true.
How about when smoking was linked to lung cancer, there were people who said that the two had nothing to do with each other. What’s the difference between the two?