I cast my mind back forty years.
People thought nothing of dropping rubbish on the ground. Only a small minority now persist. My father thought nothing of throwing cans and bottles from the car into the roadside bush. We burnt combustible rubbish in an incinerator and the rest was dumped in the bush. Although I do recall a tale of a stranger who dumped rubbish in a neighbour's bush land and an address was obtained from the rubbish and the police informed.
We we lectured at school by someone from the local fire authority about the dangers of bushfires and how to prevent them. They could be started by dumped roadside glass. A classmate collected all the glass he could find on his way home from school that afternoon, until he could carry no more. What quiet roadside would now have such a collection of glass?
Incinerators, cars, trucks, briquette heaters and hot water services, open fireplaces and solid fuel stoves used to pump huge volumes of poisonous smoke into the air.
Melbourne in Autumn was often covered in a thick soup of smog. It happens very occasionally now and the smog is not full of lead from petrol as it used to be.
Our local Yarra River downstream is cleaner than it has been for 150 years.
Our Port Phillip Bay becomes cleaner and cleaner.
After the banning of CFCs, the hole in the ozone layer is repairing itself.
Problems with greenhouse gases and global warming have been recognised and the matter is being addressed, albeit at a snails pace.
World wide, public transport is being recognised as much more sustainable than private motor car transport and a lot of money is being pumped into PT after years of neglect.
Be it in your neighbourhood or country based, if you start polluting, you may suffer the wrath of the law but you almost certainly face the wrath of activist groups that can now form at the drop of a hat due to the internet.
In spite of a proliferation of nuclear weapons, none have been used in war since WWII.
We all feel doom and gloom about the environment at times, but in the last forty years, we have come a long way, in spite of the huge population increase. If we do as well in the next forty years as we have in the past forty years, the world should be well on the way to recovering from the assault we perpetrated on her over the past couple of centuries.