Although this planet of ours is reckoned to be around 16 billion years old, since the beginning of Christianity (a mere 20c) there has always been some cranks predicting its end, some actually gave dates which came to pass yet our planet still rolls impotently on through space. There may currently be concerns over its stability caused by the industrial revolution which is increasing the velocity of change but do not forget that among the different climate changes that have occurred during the evolution of humans, our species survived the 10,000 year Ice Age. I would guess that fossil fuel is the greatest environmental pollutant today but this product will not last forever so what then; a return to genuine horse-drawn carriages or electric vehicles accompanied by a cooling of the planet; who knows? Try reading what Professor James Lovelock has to say on this subject; see:
James Lovelock - world in our hands. As the world's human population is increasing at an incredibly fast rate then something has to occur to keep it under control which may not mean total disaster but simply a control mechanism; a new set of goals within which we have to operate. One of the greatest features of humans to survive on the surface of this organic 'dung heap' is the ability to adapt so let us accentuate the positive.