BREAKING: Sixth Professor Dies In Kano In Three Days

1) Nuclear war:

A nuclear detonation from one of today’s more powerful weapons would cause a fatality rate of 80 to 95 percent in the blast zone stretching out to a radius of 4 kilometers — although “severe damage” could reach six times as far.

But it isn’t just the immediate deaths we need to worry about — it’s the nuclear winter. This is when the clouds of dust and smoke released shroud the planet and block out the sun, causing temperatures to drop, possibly for years. If 4,000 nuclear weapons were detonated — a possibility in the event of all-out nuclear war between the US and Russia, which hold the vast majority of the world’s stockpile — an untold number of people would be killed, and temperatures could drop by 8 degrees Celsius over four to five years. Humans wouldn’t be able to grow food; chaos and violence would ensue.

A big worry here is the arsenal of nukes. While numbers have fallen over several decades, the United States and Russia have just under 7,000 warheads each, the largest collections in the world. The UK, France, China, India, Pakistan, North Korea, and Israel all have nuclear weapons.
Hundreds of nuclear weapons are ready to be released within minutes, a troubling fact considering that the biggest threat of nuclear war may be an accident or miscommunication. A few times since the 1960s, Russian officers (and, in 1995, the president) narrowly decided not to launch a nuclear weapon in response to what they’d later find out were false alarms.

2) Biological and chemical warfare
Unlike nuclear weapons, which require complex engineering, biological and chemical warfare can be developed at a relatively low cost and with relatively attainable materials.
In the past few years, the Syrian government has used chemical weapons in the civil war that has ravaged the country. These chemical attacks using and chlorine have appalled the international community, and underscored the damage

3)Asteroid impact : An Asteroid:

Asteroids are minor planets, especially of the inner Solar System. Larger asteroids have also been called planetoids. These terms have historically been applied to any astronomical object orbiting the Sun that did not resolve into a disc in a telescope and was not observed to have characteristics of an active comet such as a tail. As minor planets in the outer Solar System were discovered that were found to have volatile-rich surfaces similar to comets, these came to be distinguished from the objects found in the main asteroid belt.a C-type asteroid measuring about 50 km (30 mi) across and if this asteroid should hit earth,dust and smoke rising in the atmosphere prevents sunlight from reaching our world and causes the total temperature to drop. This event can lead to the death of many living things. If an asteroid the size of an apartment hits Earth, this blow could possibly destroy a small city.