Surviving the Next Doomsday Asteroid Impact

One day, as has happened many times before, a large asteroid thousands of metres in diameter will hit our planet.

The result of the impact will rain hot debris across the entire Earth, heating the atmosphere to an oven-like temperature and shrouding it in dust clouds. Fires will burn for years adding billions of tonnes of soot to the atmosphere, and then the global temperature will fall dramatically. Photosynthesis will grind to a halt. Almost all species of plants and animals will perish. The only survivors will be those lifeforms that are able to eat the remains of long dead life, such a cockroaches and deep sea creatures.

The collision of a large asteroid thousands of metres in diameter with our planet will almost certainly result in the extinction of most lifeforms. It is unlikely that humans would survive.

If such an impact happened now humans would not survive. The extinction of our species would be certain. Essentially, life on Earth would be reset to the point just after the last massive impact event 66 million years ago (the Cretaceous-Paleogene extinction event that caused of the extinction of the dinosaurs).

By the next century we are likely to have permanently inhabited colonies on the Moon, Mars and possibly even beyond, but there will be a few hundred inhabitants at best. And most crucially those colonies will not be self-sufficient. If Earth is rendered uninhabitable and our civilisation destroyed then those colonies will die soon after. It will be a couple of centuries until self-sufficient colonies with tens of thousands (preferably millions) of people exist away from our planet. Until then we will need sanctuaries on Earth where a significant human population can survive should a massive asteroid impact occur. And by 'significant' I mean several million people at least.

The cost of building such underground sanctuaries would be extreme, and it would take decades or longer before they were ready for habitation. Hundreds of billions of dollars would be needed each year, and a workforce of millions. But it is actually affordable and achievable, if only the world's governments could be less paranoid and divert some of their defence spending to the project. The total spending each year by NATO members (29 European and North American countries) is more than one trillion dollars. If just a quarter of that budget could be redirected then the underground sanctuaries for North America and Europe could begin construction. If the likes of Russia, China, Japan and their neighbours did the same then sanctuaries in their region of the world could begin construction, too.

After a century of construction and expansion, the main chamber of a vast underground sanctuary, deep beneath mountains in Europe, is home to a thriving city of a million people. Powered by geothermal energy, the sanctuary is a self-sufficient haven for humans, one of several spread around the Earth. Even the impact of a large asteroid, such as the one that resulted in the extinction of the dinosaurs and many other species, would not lead to human extinction if such facilities exist.

Each sanctuary would need to be hundreds of metres underground, with locations beneath mountains the most preferable. As well as hundreds of kilometres of tunnels and smaller chambers there would need to be huge areas for agriculture, and even larger caverns to create the feeling of space and distance we have evolved to need, if only to maintain the sanity of individuals. Power could be generated using geothermal technology.  Energy generation using geothermal power stations currently provides 30 percent of the electricity requirements of Iceland, with the Philippines not far behind that. It is a relatively clean and renewable source of energy and would be ideal for subterranean habitats. New power generation technology, such as nuclear fusion, will hopefully be perfected over the next decades, which could provide almost unlimited power capabilities.

One of the many farming chambers that surrounds the main city of each of the underground sanctuaries. Agricultural facilities such as this, powered by geothermal energy, or even fusion energy, provide food for millions for thousands of years in the event of a catastrophic incident up on the Earth's surface.

Once created the sanctuaries would need to be permanently occupied to a high capacity: at least 50 percent. This is necessary to ensure that the sanctuaries are fully functional and under constant maintenance. They should be regularly assessed to identify areas of improvement. They would need to be totally self-sufficient if the need for them arises. There would hopefully be many months, if not years, of notice before a large impact would occur, giving plenty of time for people to migrate into the sanctuaries.

There are ethical and moral issues with regards to who would be selected to migrate into the sanctuaries should an extinction level impact be confirmed. The choice of certain sections of the population is obvious: there needs to be specialists in all areas of science and technology (engineering, medical, computing, utilities, agriculture etc) and also educators; it will be essential that education levels are maintained for the generations that will live in the sanctuaries, so schools and universities would be required.  The majority of inhabitants, however, will be ordinary citizens with ordinary levels of education and skills. Whatever method is used to choose which of those individuals and families are chosen - a lottery, or genetics (to maintain the diversity of the gene pool) - there would be objections, protests and even wars fought no matter who is chosen (there would be nations of the world without any access to sanctuaries of their own). Great care would need to be taken to ensure that the security of the sanctuaries is maintained and the chance of sabotage is kept to a minimum.

The selection of who is to migrate to the sanctuaries, and how to prevent attacks on them as they travel there, will perhaps be a more troubled process than the construction of the actual sanctuaries themselves.

Of course, it would be best if a cataclysmic asteroid collision was prevented altogether. There are numerous proposals to deflect or destroy asteroids that are identified to be on an eventual collision course with Earth. None of them has yet been tried, and all of them required many years, or even decades, of warning. Research into such methods should be intensified and an effective asteroid defence system should be implemented as soon as possible. The underground sanctuaries would allow a small percentage of our human population to survive the aftermath, but they should be considered a last resort. The need for then should ideally never arise.

Developing the ability to deflect or destroy asteroids on a collision course with Earth is essential to prevent the extinction of our species. A joint NASA and ESA mission in 2020-2021 will perform the first test of such technology.

If we construct several underground sanctuaries around the world, and deploy a system capable of destroying or deflecting asteroids, we stand an excellent chance of surviving as a species even if an object many tens of kilometres wide collides with our planet, and of eventually repopulating the surface once its ecosystem has recovered.

But, before the creation of the underground sanctuaries can happen we need to cultivate a will to change our thinking and work together for the greater good and the very preservation of our species and the wider ecosystem on which we depend. If we fail to do so we will fail all of humanity, and our extinction will be assured.