Nuclear Warfare
Despite the fact that the probability of global nuclear warfare is estimated to be at around 1 percent, even one detonation of a Nuclear Weapon could annihilate between 80 to 95 percent of the people living within a 4-kilometer radius of the impact zone.
According to the report, the largest arsenals are currently held by the US and Russia, which controls approximately 7,000 warheads each. Experts warn that In addition to their destructive effect at the point of impact, nuclear explosions may cause what is known as a ‘nuclear winter’.

Biological and chemical warfare
Biological and chemical warfare are listed as another threat to mankind which, unlike nuclear weapons which require rare materials and complex engineering can be developed at a
comparatively low cost, according to the report.

Catastrophic Climate Change
Global Temperature increase ranging from 1°C to 3°C would have severe consequences, with potentially devastating effects on the environment and human societies, scientists explain. Global climate models indicate that even in a <2°C scenario, the most intense tropical cyclones become more frequent and more intense.

Ecological collapse
As explained by experts, our planet’s ecosystems are the foundation for human life, which perform various functions without which human societies and economies could not operate at their current level. If we continue pushing ecosystems beyond their tipping point, we could diminish our planet’s bioddeveristiy which could lead to lesser freshwater supplies which would, in turn,n cause our agricultural capacity to plummet.

Pandemics
Scientists explain that during the 5th and 14th century, Plague epidemics spread internationally and killed approximately 15% of the global population over the course of a few decades. The global spread of diseases can be extremely lethal and hard to control. During 165-180, the Antonine Plague outbreak lasted for 15 years, killing an estimated 5 million people.

Asteroid Impact
Around 65 million years ago, an asteroid of about 10km in diameter struck Chicxulub in Mexico, causing what is considered one of the largest mass extinction in the history of our planet, abruptly bringing an end to dinosaurs. While such impacts are unlikely, it is not impossible. The reports explain that large asteroids still exist in orbits near the Earth’s and the impact of an asteroid bigger than 1 km in size would eject enough particles
into the atmosphere to dim the sun for a number of months.

Supervolcanic Eruption
One of the most violent volcanic eruptions occurred some 74,000 years ago when the Toa supervolcano set all ‘hell loose’. The eruption ejected billions of tonnes of dust and sulfates into the atmosphere. Experts estimate that it caused global cooling of 3-5°C for several years, and led to a devastating loss of plant and animal life. Given our current technology and understanding of supervolcanoes, we are currently unable to anticipate volcanic eruptions beyond a few weeks or months in advance.

Solar Engineering
While not necessarily a bad thing, solar engineering aims at reflecting light and heat from the sun into space with the aid of aerosols and other particles in hopes of cooling down the planet. However, solar engineering only exists in computer models and we don’t yet understand the risks or potential benefits that well. Such technology has the ability to destabilize local as well as global climates and could result in an uncontrollable, “rapid and severe global warming.”

Artificial Intelligence
Artificial intelligence has been on the rise for quite a few years. In the coming decades, there is a high probability that these systems may surpass humans in broader domains. The danger of entities more intelligent than us can be understood by considering the power we humans have drawn from being the smartest creatures on the planet.