It's baffling to many of us why people are so reluctant to listen to scientists on the topic of climate change and why groups of us, even the Republican party, seemed determined to ignore and dismiss the science behind it.
Humans seem to frequently engage in denial, especially on issues of a cataclysmic nature for either the planet or ourselves personally. Look at how death has spawned so much superstition, all of it intended to assure ourselves that this apparently inevitable personal catastrophe can somehow be avoided.
It often takes an event becoming imminent to jar us into dealing with it. Speculation about climate change, comet strikes, even the possible hacking of our electrical grid or the possibility of martial law or a theocracy isn't enough to get Americans to take these threats seriously and support funding to find a way to deflect or prevent their occurrence. Even people who are not usually skeptical are reluctant to face such massive and life altering events, preferring to cast doubt on the speculations or find alternative, more reassuring possibilities. The more likely the life altering event, the more desperately humans will seek to deny its inevitable occurrence.
We don't want to believe that we've had a profound and possibly irreversible impact on the planet. We don't want to accept responsibility for having perhaps doomed our species to extinction. We want to believe our superior brains and human ingenuity will once again save the day and prevent an apocalyptic event. We want to believe our species has millions of years ahead of it yet.
There's also an element of selfishness involved. We want to believe that if the planet is undergoing a dramatic change that will effect our lives on a major scale, it will likely take decades if not centuries to occur. We won't have to deal with it personally. We tell ourselves that science or technology will find a solution by the time it becomes an imminent reality.
Another factor in play is the fact that the majority of humanity believes in supernatural gods who look after us and wouldn't allow the planet to become unlivable. If science or technology fail to find a way to make everything right again then their god will. One way or another we'll be spared from having to accept responsibility for our actions and the world will be saved by someone or something down the road.