This is just a story. Usage of imagination is recommended. This CAN be prevented.
Year 2011. People being people, are using the biggest of plastic bags for the smallest of things. People being people, the biggest of cars are only occupied by one individual. People being people, they are ignorant. They want to enjoy in the present and don't look to the future, no matter how aware they were.
Typical type of humans ; They do something that they know they'll regret in the future. Typical humans - are stupid.
As the years went by, scientists began to uncover new areas that has a lot of fuel supplies, but at the same time technology experts are inventing new forms of technology that requires a darn lot of electricity which uses petroleum, and humans being humans, they prefer the joy rather than the consequences of having no more resources.
The search for petroleum itself requires fuel. Twenty years later, it becomes harder and harder to find the fossil fuels, and the scientists decided that it would just waste fuel in searching, knowing that they won't find any more. The coal has become so close to depleting, and there were no more mining fields that are to be uncovered. Natural gas are also depleted.
After giving up on their search for fossil fuels, scientists decided to keep a few million litres - just in case. The advance in technology finally allows them to make cars that run on "unlimited" resources - water and biomass mostly. The human race became relaxed of the fact that they finally have a hope to stay alive. But humans being humans - some were very greedy. They guzzled these unlimited resources just like they had done with the limited - except they did so more, because of the thought that these resources were unlimited.
It is the year 2108. The human race were on the brink of extinction. The resources that made the third planet of the Solar System a special one - were wiped off the face of the planet. What was once the seas were nothing but rocks and what used to be corals. Many fish lay on those rocks - dead. The forests were shaven bald, they were no more. The only planet which is just perfect for living has been destroyed, not by alien life - by the inhabitants itself.
The humans had nothing to eat - how can they have anything, if the animals that was their food source are extinct themselves? The animals have nowhere to live. Even pet cats and dogs escaped from their owners - else they will be eaten under desperation for food. Humans start killing each other just for something to eat. It became more of a hobby.
There were no more greeneries. Even water, what that was claimed to be unlimited, was becoming very, very scarce. Beaches turned into a rocky desert. The ice at the Two Poles were all melted - and the water produced from the melt was nowhere to be found. Every drop of rain became very, very valuable - people started drinking raindrops, and just a drop was enough to quench their dying of thirst.
And the best part - all the greedy men, the fuel guzzlers and the ones that didn't even care of the future, are now the ones with hearts full of regret. But regret is nothing now, it is already too late to change anything. The resources we boast about are no more, except for the always-precious air. And now the men are paying the scientists to invent things with air, but what was the use? Even if they succeeded, the Earth they once knew, the planet they once loved, was nothing any more. All the beauties were lost.
Slowly and slowly, one by one of men and women, children and babies started to die. The men had lost hope, and so had the women. Children and babies starve to death. The last of people cried and cried before their deaths - regretting the fact that they once had everything they needed - but they were wasted. And now they were no more. And now, there will be no time machine to turn back and eradicate all the ignorance. As quoted, "People will not know the true value of something - until they lose it."
But by that time, it'd be already too late.
This can be stopped. You can start by just turning off a switch, or car pooling, or using public transport, or conserving fuel by using transports such as bicycles or your two feet. There are more than 5 billion people on Earth. If they all act together, than the possibility of the scientists successfully discovering a new resource to start over with is likelier than us dying before the scientists make a progress.
It's our Earth. We can save it together (: