© Eric R. Pianka
Some pseudo-scientists under the payroll of big oil assert that oil supplies are adequate to get us through to the end of 2100, but no one knows how long dwindling supplies will last in the face of rapidly increasing world wide demand. We probably have already reached "Hubbert's Peak."
Burning of fossil fuels has released large amounts of carbon dioxide levels into Earth's atmosphere. By reflecting heat back to the planet that would otherwise radiate out into space, greenhouse gases such as CO2 and methane have warmed the Earth's land surface and oceans (see global warming).
Until the advent of agriculture about 10,000 years ago, humans were hunter gatherers -- many fewer of us existed. Agriculture allowed humans to increase in population density, ultimately leading to the present day overpopulation crisis. We could never have reached 6.8+ billion without fossil fuels. Basically, humans exploited these one-time fossil energy reserves to demolish many of Earth's natural ecosystems and turn them into arable land and crops to feed increasing numbers of people. We replaced the tall grass prairies of North America with fields of corn and wheat and turned bison herds into cattle, ultimately into masses of humanity.
The ancient deep black topsoils of the prairies made America a 'bread basket' for the world, allowing us to export grains to less fortunate peoples in other parts of the world without access to such amenable climates and rich soils. Sustained agriculture depletes the nutrient pools of soils -- in order to maintain production, soils must be fertilized with nitrogen and phosphorus and other minerals. Animal wastes such as bat and bird guano were used as fertilizers until they began to be depleted. Then, just as such natural fertilizers were running out, the Haber-Bosch process was discovered, which uses energy from burning natural gas to fix atmospheric nitrogen, essentially turning air into fertilizer. Without this technological breakthrough, human populations would have become limited by food supplies long ago and at much lower population densities. Technology lures us out on to thin ice, and we now face population overshoot. Our enormous population, now well above the level Earth can support, must soon crash, accompanied by famines and massive human misery.
Americans are now suffering from painful increases in the cost of gasoline at the pumps with no end in sight. People are clamouring for alternative new sources of energy such as nuclear energy. Many seem to think that we don't have to obey laws of thermodynamics. Using energy always produces heat, and unless it is dissipated, temperatures must rise. Earth can no longer dissipate the heat it receives from normal incident solar radiation fast enough to stay in balance (Hansen et al. 2005), even without our adding insult to injury by burning fossil fuels and using nuclear reactors.
Because people have electrical outlets all over their houses and offices, they suffer from the illusion that electricity is clean energy, infinite in supply and will always be there. None of these assumptions is true -- unless we convert to an electrical system based on renewable resources such as solar energy, power grids must ultimately fail and the internet will cease to be. Whenever you turn on a light or an air conditioner, fossil fuel is usually being burned to generate the electricity you're using. A relatively small amount of electricity is generated by other sources such as by wind, hydro-electric, and/or solar energy. When you turn on a light, you are releasing solar energy captured by plants millions of years ago -- essentially, you are being illuminated by fossil sunlight that fell on the Earth long ago. Unfortunately, electricity is difficult to store and usually must be used immediately. Battery technology to improve our ability to store electric energy has been painfully slow.
Converting to a solar-powered electrical energy system would greatly reduce carbon emissions from the burning of non-renewable fossil fuels. Switching over to renewable sources of energy (wind and sun) would also make our electrical grid system more stable and reliable in the future.
Of course, humans are clever, so clever that we have actually figured out how to turn matter into energy exploiting fission and fusion. Some seem to think that energy is available in infinite supply. Nuclear energy may be virtually limitless, but it carries serious environmental hazards (particularly thermal pollution and radioactive waste). Access to unlimited energy would lead to our downfall (see also below).
Unlimited cheap clean energy, such as that so ardently hoped for in the concept of cold fusion, would actually be one of the worst things that could possibly befall humanity. Such energy would enable well meaning but uninformed massive energy consumption and habitat destruction (i.e., mountains would be leveled and terraced, massive water canals would be dug, ocean water distilled, water would be pumped and deserts turned into green fields of crops). Human populations would grow even higher and the last vestiges of natural habitats would all be destroyed. Heat dissipation would of course set limits, for when more heat is produced than can be dissipated, the resulting thermal pollution would quickly warm the atmosphere to the point that all life is threatened, perhaps the ultimate ecocatastrophe.
Our economic system based on continual growth must be replaced by a sustainable system where each of us leaves the planet in the same condition that it was in before we were born. This will require many fewer of us and much less extravagant lifestyles. We won't be able to move around so freely (airplanes will become a thing of the past) and we will have to go back to walking and riding horses. In addition, humans will have to be more spread out, living without big cities. Before it is all over, we are going to have to grow our own crops, limit our own reproduction, un-invent money, control human greed, and revert back to trade and barter, among other things (see also Can human instincts be controlled?).