Simple human psychology dictates that people do not cope well with bad news. Since the death of planet earth is the worse possible news anyone could ever hear, there will be those with sufficient defense mechanisms, to deny it. Defense mechanisms worked great when humanity evolved over the last one million years. But now, with over population and over use of resources, they must be reexamined.
The earth, once supporting fewer than seven billion people, historically had enormous stores of resources. It is only quite recently that an untried and unparalleled event of resource depletion, and diversity destruction, by way of fossil fuel consumption is occurring.
This does not mean humans need to save the earth. For most mass extinctions, humans were not even present. However, what people do decide is acceptable, living in vastly deteriorated landscapes, or not, is up to humanity. To contaminate one's own home is unwise in every interpretation of common sense. To add toxins, pollutants, and a serious degeneration of all self-sustaining bio-diversity is clearly insane.
People then, are insanely connected to the idea that they have power over nature, which no species can have. They do not realize they can adapt the power of conservation, or that belonging to earth is liberating rather then enslaving. The primary reason people are skeptical about proof of global warming, is that they know they have been fooled before. They also know that buying green products is not likely a solution, even in those instances when hybrids may help.
Ecopsychology is the field of well being that teaches belonging. And belonging is the broad foundation of all life and all exchanges of energy. When people recognize what is needed for sustaining ecosystems, they are better able to realize what to protect and defend.
The attendant symptoms of a sick society include crime, pollution, hate, selfishness, greed, apathy, helplessness, and all the blights and diseases which a common strong immunity can no longer defend against. That is, disconnection causes conflicts, and in the wake of those conflicts, turf wars, and wasted landscapes, is often hunger and need, disease, and deteriorated infrastructure. People who need to belong to any "tribe" are naturally going to see outsiders as scapegoats. This is not a recent development, in the same way that resource depletion on a massive scale has become.
A poor knowledge of what people are made of, what systems need to survive and exchange heat, fuel, water, soil, and more is what creates misunderstanding of the human place in any ecosystem. It is neither entirely due to religion or ideology, but almost always by a need for people to believe that they belong to the chosen few. The ability to believe one belongs not to the chosen few, but to the entire cosmos, is a a thought outside the bubble that has also been repeated in history, and has proven effective for people and other organisms to appreciate their mutual inclusion.
Prior to Industrialization, people lived closer to earth and sensed their place and belonging in the inter active ecosystems. People are still completely dependent upon air, food, soil and water, but people collectively behave as though they are somehow "above" or in charge of, these dynamic systems. Life is needed for life, humanity is not needed as a master in any sense. Native peoples have notably nearly always expressed kinship to animals, forests, skies and earth.
People drawn to new age thinking respect native species, including humans. The only problem with that is when people engage in magical thinking rather than fact and science based "faith." There may be no such beast, as the noble savage, a myth debunked, but there is the reality of living more deeply in touch with the sustaining, and supportive world. When people can be convinced, and it may only take over whelming proof, they will change destructive habits into constructive and conservation habits.