10 POSSIBILITIES FOR THE END OF THE WORLD

1.    Asteroid Explosion

The reason for the demise of the dinosaurs was linked to the impact of a 10km asteroid in Mexico about 6500000 years ago. In 1908, an asteroid of about 110m across exploded 6km above the Earth, releasing energy equivalent to a thousand Hiroshima’s over Siberia.
The end of humans could be caused by a 1km wide asteroid which would sweep in from the sky, hit earth at about 20kms per second and scoop out a crater 10km across, throwing huge mass of rocks into atmosphere. 45 minutes later, blazing fragments of earth would begin to reduce it to ashes.
The solution to this could be a nuclear explosion detonated at the distance of a radius 500 m (in the case of a 1km asteroid) which could slow or deflect the asteroid even if it was to collide in 20 years. There would be no explosion in space but a side of the monster would start to vaporize. This would have a pushing effect, and could slow the monster by half an inch a second. It may not sound effective, but half an inch over 20 years adds up to greater than the radius of the Earth. It would miss us.

2.    Robotic invasion

Robots are being used all over the world in military operations, carrying military weapons and can easily identify human targets on their own.
In the next 20 years, each house will have its own slave robot.
Soon with the development of technology these robots will have a higher artificial intelligence level and if they come to know that the less intelligent humans are their rulers and they can easily have a victory over us, then they will rule us and if we deny they will end the human civilization.
Or they may even fall prey in the hands of some angry terrorists pissed off for no reason who could reprogram them for the doom of the world.

3.    Super volcano

Tambora erupted in 1815 with a high rating on the Volcanic Explosivity Index, making it the largest of the eruptions ever since the Lake Taupo eruption in 180 CE. The death toll was more than seventy thousand people. The eruption created global climate calamity. 1816 became to be known as Year without summer because of its effect on the American and European weather. Agricultural crops failed and cattle died in many areas of the Northern Hemisphere, resulting in one of the worst famine of the nineteenth century.
One huge eruption like this could be enough to trigger many other sleeping volcanoes which could result in the end of the world.

4.    Alien Invasion

Taken to account that there are roughly 1011 galaxies, every galaxy having 1011 stars and every star having its own solar system, the probability of life on other planets is a likely one. Also the infinite number of parallel universes, there the possibility of intelligent beings on other planets is expanded quite a bit.  Extraterrestrials, if they reach earth, will be lac ties more intelligent than us as the distance between earth and stars is hundreds of light years.

5.    Global warming

Global warming has been a topic of concern for a very long time. But we are least bothered as it would take 60 to 100 years before we will actually have to deal with its effects.
The idea is that global warming could cause the gulf stream to just stop, significantly lowering the temperature in Europe, possibly making places like Iceland and Finland uninhabitable, and the UK with temperatures more like Moscow. This could mean an ice age for the world and end of human civilization.
Personally, I suspect warmer summers and colder winters are the most likely outcome as the Gulf Stream weakens. It will make summers warmer and fail to bring the winter warmth.

6.    Invasion of grey goo

Grey goo is a kind of nano device which takes in biomass and turns it into copies of its grey goo device. If such a device were not controlled, it could eat the whole biosphere. We may develop this technology which would be able to dissolute blood clumps, stop the cancer causing agents and protect us but what if this technology starts growing and making everything like it which comes in its way.

7.    Nuclear Holocaust

World War 3 would mean the end of human civilization as there is a wide possibility of usage of nuclear weapons. Single nuclear blast would be powerful enough to end the human civilization.
A nuclear explosion has both immediate and delayed destructive effects. Immediate effects such as blast, shock wave and radiations are produced and cause huge destruction within seconds of a nuclear detonation. The delayed and lingering effects include radiated mess, poisonous rain and contaminated atmosphere causing damage over an extended period ranging from few hours to centuries.

8.    BIO BOMBS

Today Scientists have claimed producing new viruses that attack bacteria for environmental purposes. If used as biological weapons, it could pose a serious threat to humans. Already groups of people are discussing the possibility of HIV and Ebola being man-made in a military laboratory. Only time will tell the authenticity of this fact. Meanwhile we are facing the threat of natural viruses altering their own genetics in an increasingly rapid pace. There is a distinct possibility the Spanish flu (1918), in which millions of people died from influenza, can be repeated in the near future. Scientists also fear that the number of deaths resulting from this new virus would be many times higher. It could well prove to be a virus for which no immunization would be possible to develop and could be a possible reason for end of the world.

9.    Killer Mutants

With the help of genetic technology we can get any character of any organism in humans by intersecting a part of its gene in human chromosome. We can mutate the humans by increasing the number of intelligent genes responsible for human intelligence and they could be highly powerful and ready to rule. In the next hundreds of years earth will be divided in 2 groups- Genetically mutated organisms (Rulers/killers) and original humans (slaves) which would slowly end the whole of human civilization.

10.    Earth to spin off its axis

Earth spins because of the way it was formed. As the cloud of gas collapsed during the big bang, it started to spin. Some of the material within this cloud gathered and eventually formed into planets. As the planets were formed, this spinning motion was inherited. As material gathered in more closely to form a planet (like Earth), the material spun faster. The Earth keeps on spinning because there are no frictional forces acting to stop it. Even a small change in axis is dangerous as the atmosphere will become extreme hot or cold for the humans to survive.