Humans have been there on earth for a long time, but we don’t know how long we will still survive here. Before us, dinosaurs were there but they got extinct because of an asteroid.
Now the question arises, how much time do humans have left? When is the last working day on Earth?
Let’s find out what are the possible ways that may end human life on earth:-
Another Mass Extinction By An Asteroid
When a city-size asteroid struck the earth 66 million years ago, dinosaurs, as well as many other species of animals on Earth, got extinct at that time. And although our ancestors did not change, the impact was perhaps one of the most important events in the history of mankind. Without that asteroid strike, dinosaurs may have continued to dominate the Earth, leaving us mammals still in the shadows.
Humans, however, will not always be on the winning side of such random events. A future asteroid could easily land anywhere on Earth. Fortunately, that is not possible soon. Based on a geographical record of the effects of the universe, the Earth was hit by a massive spacecraft almost 100 million years ago, according to NASA. However, minor asteroid impacts occur all the time. There is also an evidence that some people may have been killed by small meteorite impacts during the last few thousand years.
But what are the chances that our planet will ever be hit by a star large enough to wipe out all life on Earth? Imitations published in Nature back in 2017 suggested that it would take a huge rock of space to do such a job.
Killing all living things on Earth will require the effect of literally boiling the oceans. And only asteroids like the Pallas and the Vesta – the largest in the solar system – are big enough to do just that. There is an evidence that the baby of the earth was struck by a giant planet called Theia. But these days, conflicts of such magnitude do not occur at all.
In order to get a glimpse of the catastrophe that is changing the world, we need to look back.
Oxygen Depletion
Nearly 2.5 billion years ago, the Great Oxidation Event gave us a breath of fresh air that we all depend on now. Explosions of cyanobacteria, sometimes called blue-green algae, replenish our supply of oxygen, create a world where multicellular organisms can trap, and where human beings can breathe.
However, one of the world’s major events, the Late Ordovician mass extinction 450 million years ago, probably happened because the opposite happened. The planet saw a sudden decline in oxygen levels that lasted several million years.
During the Ordovician era, the continents were a mixed mass called Gondwana. Many of the animals that were on earth at the time were living in the sea, but the plants were growing on the earth. Then, towards the end of the Ordovician era, a dramatic change of weather left the continent covered with glaciers.
However, the second rate of extinction increased as oxygen levels dropped. Scientists see evidence of this shift in low-lying samples from around the world. Some researchers think that glaciers are the major culprits in changing oceans, with different temperatures and the concentration of certain elements, such as oxygen. But the exact cause of the decline is still under discussion.
More than 80 percent of life on Earth died during the Late Ordovician mass extinction, according to some estimates.
There might be another such event in the future that would wipe out human civilization.
Gamma-Ray Burst
Gamma-Ray bursts( GRBs) are mysterious phenomena that appear to be the most violent and powerful eruptions in the universe, and astronomers suspect that they are related to supernovae. But since we have never seen it, we don’t know much about it, but a lot of them have been detected in a few galaxies.
But if it happens in the Milky Way, as it could in the past, it could cause global catastrophes. The GRB targeted for us may last for 10 seconds or more, but it can still deplete at least half of the Earth’s ozone in that short period of time. As humans have learned in recent decades, even the smallest amount of ozone depletion is still sufficient to eliminate the sun’s rays, which cause serious problems. Ozone depletion can cause severe damage to food chains, killing countless species of living things.
The GRB will eradicate species that live at high levels of the oceans, currently providing significant amounts of oxygen in our atmosphere. Also, it turns out, gamma rays also separate atmospheric oxygen and nitrogen. These gases are converted into nitrogen dioxide, which is more commonly known as a smoke barrier seen in most polluted cities. Having this smoke all over the world can block sunlight and trigger a global snowstorm.
Any of the harmful conditions above, though not necessarily bad in life, are as bad as the end of the world. Gamma-ray explodes or not, in about a billion years, many lives on Earth will eventually die of malnutrition. That is according to a separate study published in March in the journal Nature Geoscience.
Researchers have suggested that our oxygen-rich atmosphere is not a permanent feature of the planet. Instead, for about a billion years, the sun’s activity will cause the atmospheric oxygen level to drop to its normal pre-Oxidation count. To determine this, the authors combine meteorological models with biogeochemistry models to mimic what will happen in space as the Sun ages and releases more energy.
They find that, eventually, the Earth reaches a point where carbon dioxide in the atmosphere breaks down. At that time, plants and oxygen-producing organisms that rely on photosynthesis will die. Our planet will not contain enough life-forms to sustain the life-forms of humans and other animals.
Exactly when and how long it starts – the oxygen process can take as little as 10,000 years – depending on a variety of factors. But, finally, the authors say that this catastrophe is inevitable in the world.
Sun Reaching It’s End
In about a billion years, sunlight will be 10% higher than it is now. This will cause the atmosphere to become a “wet greenhouse”, leading to evaporation. As a possible consequence, the tectonic plates will end, and throughout the carbon cycle.
After this event, in about 2-3 billion years, the earth’s magnetic dynamo may collapse, causing the magnetosphere to decay and lead to the rapid loss of flexibility from outer space.
Four billion years from now, global warming will have a catastrophic effect on the greenhouse, creating conditions worse than today’s Venus and hot enough to melt.
At that time, all living things on earth will be gone. The most probable end to this planet is the absorption by the Sun about 7.5 billion years, after the star has entered a large red phase and expanded beyond the current planet’s orbit.
Nuclear Warfare
The detonation of nuclear weapons from one of the most powerful weapons in the world today could cause a death toll of 80 to 95 percent in an explosion of up to 4 miles (4 km) – though “significant damage” can be up to six times.
But it is not just death that we have to worry about – nuclear winter. This is where clouds of dust and smoke emanate from cover the planet and block out the sun, causing temperatures to plummet for years.
If 4,000 nuclear weapons will detonate – possibly in the event of a nuclear war between the US and Russia, with most of the world’s assets – an unprecedented number of people could be killed, and temperatures could drop by 8° C in four to five years. People would not be able to grow food; chaos and violence would follow.
The biggest concern here is the arsenal of nukes. Although numbers have declined over the past few decades, the United States and Russia have fewer than 7,000 warheads each, the largest 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 in a matter of minutes, which is a disturbing fact considering the serious threat of a nuclear war could be a threat or a misunderstanding. A few times since the 1960s, Russian officials (once, in 1995, with the president) decided not to launch a nuclear weapon in response to what they later found to be false alarms.
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