Our world is more fragile than we like to think. Ecosystems, the atmosphere, and the relative geological calm upon which we rely for our continued existence as a species, are phenomena that did not always exist, and will almost certainly cease to exist at some point in the future. The threats to our existence are many, and they can be divided into human-created (anthropogenic) sources, and natural sources. There are also scenarios in which natural side-effects can be caused by anthropogenic causes, most notably climate change.
Let’s take a look at the anthropogenic threats first of all. The most obvious of these is arguably climate change, with nuclear war a very close second. The misuse of biotechnology is another distinct threat, with biologically engineered weapons being a realistic worry.
Any one of these anthropogenic scenarios could spell doom for us: global warming could lead to catastrophic loss of biodiversity, a breakdown of the food-producing services of worldwide ecosystems, and an increase in communicable diseases. A nuclear war could destroy the planet’s habitable atmosphere and block out the light from the sun, while unleashing deadly radiation. A bio-weapon could be released in the form of a pandemic disease, with devastation comparable to that caused by the medieval Black Death.
Natural threats are just as serious, if not more so, since some of them have a near-100% certainty of occurrence. For example, one day the Sun will expand to the extent that human life, if it still exists on Earth at that time, will be completely eradicated. Of course, that won’t be for about 2 to 5 billion years in the future, but the fact remains that it will almost certainly happen. Also, one day the Earth will almost certainly be hit by an asteroid so colossal that it will destroy life on Earth as we know it, and it will therefore have the capability of destroying human civilization, if it still exists. It could happen in a million years. Or it could happen in ten, or less. Such events occur on average every 500,000 years. Smaller near-earth objects are tracked by NASA every day. A major asteroid collision isn’t a ‘maybe’, it’s an ‘eventually’.
But it doesn’t take a dying star or a wayward rock to put a stop to human endeavour. Loss of ecological services, such as pollination performed by bees, or nitrogen-fixing by certain plants, could lead to entire ecosystems crashing, disrupting the balance of gases in the atmosphere and even causing crop failure. A rise in temperature of only a few degrees could lead to the loss of large areas of agricultural land, causing not only drought and famine, but potentially war and the destabilisation of the global economy. A massive volcanic eruption would have some of the same effects as a nuclear war, causing widespread crop failure and weather disruption. All of these are near-future possibilities.
Earth’s currently habitable state is fragile and precarious. Humanity is at significant risk of extinction so long as it has only one home. Space exploration could provide a way out of this dangerous position. Besides benefits such as the expansion of scientific knowledge, the unification of nations through shared space programs, and the acquisition of new sources of natural minerals and fuels, the colonization of space will reduce the risk of extinction by ensuring that populations exist elsewhere in space, should a catastrophe ever occur.
But we had better act fast. If we were to deplete Earth’s natural resources before we found new sources, our species would be stranded on this planet with no means of further exploration. As resources are already limited, space exploration should be one of humankind’s top priorities, alongside achieving food security and stabilising population growth. After all, its benefits won’t just enhance life on Earth, they could save it.