It seems to be generally agreed that the effect that mankind is having on the planet is negative - I include all the issues that have been raised here - global warming, car pollution, smoking pollution, many other forms of pollution, poor farming habits and on and on. The important question to me is what should we do about it. I will start out with 4 options - I am sure there are many more.
1 Nothing. The Earth will take care of itself. It has for over 4 billion years and a little flea like us is irrelevant to it. Tornadoes, rising, falling sea levels, heating, cooling, volcanoes, population explosions or extinctions are part of the natural history of the Earth and it is arrogant of us as a species to consider ourselves important. If 65 million years ago 90 odd % of life was wiped out but here we are now as we are then let's trust the Earth to look after itself. A species dies out - so another takes its place. Who cares about pandas anyway? Don't like this option? - then it is probable that it is not the Earth we are worried about but mankind. Our children and our children's children.
2 Crash and burn our current civilisation - and make sure you denigrate the term civilisation itself. We are greedy and uncaring because we like modern comforts so we should all wear hair shirts and go back to living as our forefathers did before the Industrial Revolution.
3 Make plans to decimate the human population. A total ban on any couple having more than one child. In three generations the child-bearing population base would be one eighth (although it would take longer than this for total population to reduce to that figure). Thereafter you could revert to 2 children per family for a long term stable population.
4 Go eco-light. Look for the areas where we do most harm and try to ameliorate them. Stop making gas guzzler cars, promote better public transport, encourage alternative ways of communicating and working which do not involve travel, use taxes and subsidies to encourage environmentally positive and discourage environmentally negative activities. Protect species in danger and work to reduce pollution levels worldwide. Do all this within the constarints of a modern industrial society and without forcing people to give up things they enjoy and without destroying modern corporations - rather by regulating them.