Humans cannot help but wonder what the future holds, whether for themselves or their children’s children. Religions around the world have come up with varied answers. Hinduism sees existence as extending indefinitely over vast cycles of time, in which individual souls are endlessly reincarnated. Other faiths, such as Christianity, envisage an apocalyptic end to human life on Earth within a definite (but unknowable) period or time, followed by a timeless eternity, in which the good are taken up to heaven and the wicked cast down to hell.
Today, however, many people are as likely to look to the predictions and models of scientists for glimpses of the likely future of our species, and our planet. The debate over climate warming and its likely impact on life on Earth has helped to focus minds. In November 2015, the World Meteorological Organization indicated that the year would be the hottest on record, with man-made emissions the chief cause. The average global temperature in February 2016 was higher by 1.35°C than that month’s average for 1951–1980. Part of the rise in 2015 may have been caused by El Niño, a natural and mobile weather pattern marked by warming sea-surface temperatures in the Pacific; indeed the El Niño that year was one of the strongest on record.
The many conflicting interests of states and populations around the world make it hard to reach international agreements, not only on climate change, but also on other important issues. Rising population levels have created environmental pressures in many regions. Competition for resources such as oil has already led to extensive conflicts. Although the burning of fossil fuels contributes to global warming, oil still underpins large sectors of the global economy, and also the way of life of millions of people. Unless more effort is put into developing new and more sustainable sources of energy, the eventual depletion of oil reserves may well have an enormously disruptive impact on the way many of us live.
In the future, other natural resources, such as fresh water, are likely to lead to conflict. In the Middle East, for example, the rivers Tigris and Euphrates are vital sources of water for Iraq and Syria, but the amount they channel has been limited by the construction upstream in Turkey of dams for irrigation and hydroelectricity. The countries concerned have yet to come to an agreement over water sharing. Within countries, too, rising water consumption has depleted natural aquifers. In India, the boom in rice cultivation in the Punjab from the 1960s resulted in a serious drop in the water table. Extractions from the water table by manufacturing industry is a growing issue both in India and elsewhere. In 1990s Australia, the use of irrigation for cotton and rice in the Murray– Darling basin led to the movement of salt to the surface and to major losses of cultivable land. Something similar had occurred millennia before in ancient Mesopotamia.
‘All I know about the future is that it is what you make of it.’
Walter Mosley, US novelist (1998)
Unless humans cooperate more effectively on the global scale, competition and conflict over diminishing resources are likely to lead to increasing disorder. If global warming remains unchecked, many parts of the world will end up uninhabitable, for example because of flooding or desertification. This would lead to great flows of refugees. It may be better to deal with the causes before we have to deal with the consequences.
If global warming continues, there is a possibility that agricultural productivity could collapse, and the resulting food shortages could spell the end of human life on the planet. However, there are other less predictable ways in which the human species might perish. Some of the more extreme scenarios include large-scale nuclear war, which could wipe out many in a moment. If any life forms managed to survive the blasts and the radiation, they might not be able to live through the ensuing nuclear winter: with so much debris thrown up into the atmosphere, the Sun’s light could be blocked out for years, killing off the plant life at the foot of most food chains. A similar nuclear winter could be caused by the impact of a large meteor or a comet, or by the eruption of a supervolcano like the Yellowstone Caldera.
At the more bizarre end of the spectrum, science fiction has often imagined our world being invaded by hostile alien creatures. However, in spite of our much improved ability to observe other planets, and the discovery of water elsewhere in our own solar system, this remains a rather remote prospect. There is nonetheless the possibility of an enemy closer to home: a disease pandemic of such severity that the human species is wiped out. Some culprits for such a possible extermination include new strains of influenza, the Ebola virus, the return of the Black Death, a variation on the HIV/AIDS virus, extreme drug-resistant tuberculosis, a leak from biological warfare stockpiles, or perhaps another disease which we have not yet even heard of.
Many species of animal have already become extinct, and it is entirely possible that it will be the turn of our species to face extinction in the future. Even if we do survive that long, in a billion years or so, the Sun will become so hot that water on Earth will not stay liquid. As a result, all life on Earth will be extinguished.
Long after that, about 5 billion years from now, the Sun – like other stars of its size – will grow massively larger and become what astronomers call a red giant. This expansion will engulf all the inner planets, including the Earth.
‘Earth felt the wound, and Nature from her seat Sighing through all her works gave signs of woe, That all was lost.’
John Milton, Paradise Lost , Book IX (1667)
We are in the early years of space travel, and it is uncertain whether we will ever be able to voyage between solar systems. However, when the Sun starts to get significantly hotter and expand, that may be the only way – if we haven’t already become extinct – that human life can continue thereafter.