The Story
People today are abusing the planet far worse than we ever used to, causing the Earth's weather to change. The ice caps are going to melt, coastal cities are going to be inundated, storms will become more and more disastrous, and we are all going to die.
If we could all go back to a more responsible lifestyle, the damage would reverse and the Earth's climate would return to its normally stable state.
Facts
As individuals, we are abusing the planet more, but not that much. The real problem is that there are so many more of us than there used to be. It's simply not possible for a society of ten billion people to survive using the same amount of resources and producing the same amount of waste as fewer than one billion people did two hundred years ago.
But even if that was possible, the climate would still change. It might be true that human activity has increased the rate at which glaciers are melting, but it's not humans that are the cause of their melting.
To claim that we are capable of preventing this change, that we are able to perpetually maintain the Earth with a stable climate, and even that we are currently living in the Earth's ideal state, is nothing but self-important arrogance.
Thousands of years ago, Earth was in an ice age, with much of the world covered in ice. The Great Lakes were created by the pressure and movement of a monstrous glacier, three or four kilometers thick. Ever since then, the world has been warming, the ice has been melting, and the glaciers have been receding.
The difference between a 3 kilometer thick layer of ice and our current summer weather represents a massive change in our climate. Humans might be able, whether intentionally or inadvertently, to speed up or slow down the rate of climate change by a very small amount, but there is no way we are capable of either causing it or preventing it.
It's not even obvious that climate change is a problem. For instance, does it really mater that the oceans are slowly rising? Once we become aware of this, we can simply stop erecting new buildings in areas we know will become inundated and, over the next few decades or century, build new cities further inland and slowly migrate our population there.
There real problem is not climate change, but that this solution will no longer work because we have massively overpopulated the world and have already built cities in those locations where we would move to. Expanding the capacity of a ferry by carrying additional passengers in its life boats is not a good way to operate a commuter service, much less a planet.
Why
People love to champion causes, love to have a simple view of the world, and love to have simple solutions to all kinds of problems. Climate change is definitely a problem, but simple feel-good solutions to contrived problems powered by guilt are not useful for anything, except to advertisers and other social manipulators.