How did you imagine the end of the Earth? Meteor strike? Maybe alien invasion or something else? Unfortunately, I have to say that human negligence and the effect of people are the closest to destruction of the world.
One of my favorite quotes is the one from Einstein:
People have a habit of throwing trash, leaving lights turned on and overspending drinking water while a quarter of population are in desperate need of it. Companies are producing more and more while we, as consumers, spend even more. Waste is collecting and it won't disappear, trust me.
My thoughts are that we should definitely use renewable energy sources because it is literally the usage of Earth's energy sources to save and redemption of Earth itself.
We must not underestimate the power of nature!
On the basis of how we treat the Earth, it might strike us back just as Newton said:
Cars and factories are very polluting and consequences are already visible.
The results are extinction of animal species, ozone holes and health disorders.
Moreover, climate change and natural disasters are results of that as well. Is that what we want? Is that what we love?
Scientists predict reduction of drinking water, among other things. I'm worried that it wouldn't be a reason of next big war in a future. I'm not a pessimist, there's a possibility.
We, the most intelligent creatures, have to devise a solution for a better life.
To avoid all this, I came up with an idea to associate as many good people as possible to improve our situation. Imagine a person who stopped throwing trash on the floor... It is nice and preferably, but... there is no big difference. Now imagine every single individual from all over the world do the same, that's quite a lot isn't it? I suggest that we should join as people and do the best for ourselves.
Nothing goes overnight, it's all about patience and self-control and everyone should give best from yourselves. Gradually, through some period, things would go to the better. We should all work together and we could achieve our dreams and idyll we dram about.
In my opinion, recycling is the main priority besides waste incineration and we need to use renewable energy sources. We have water, wind and sunlight which can be used in various necessary forms. A problem with waste disposal would be solved, high cost of electric energy would go to oblivion with solar panels, hydro power plants and windmils.
RECYCLE, KEEP THE EARTH CLEAN & KEEP IT GREEN!
@tonac--> shottout to 
It's beautiful how someone you don't know can give you an idea and motivation.