In calling for an immediate end to fossil fuel use, I have risked overlooking a serious problem; a planet without fossil fuel can’t support as many people as currently live here. A third of greenhouse gas emissions are related to agriculture, through agricultural machinery, food processing, petroleum-derived fertilizers, irrigation pumping, food transportation, and the clearing of land. Without fossil fuel, we couldn’t produce as much food as we do. In plain terms, if the oil tap turned off tomorrow, some number of people would starve to death.
Of course, the situation is complicated by so many other factors that we don’t really need to worry about this.
Most obviously, the real threat is not that we’ll quit using oil too abruptly but that we won’t voluntarily quit at all, in which case huge numbers of people will die anyway, from food and water shortages and extreme weather. Even the most rapid plausible shift away from fossil fuel will likely be gradual enough that we could reduce our population through simple attrition. Ultimately, getting off fossil fuel as quickly as possible is probably the safer course for humans individually as well as for our species and our planet as a whole.
Besides that, the absolute amount of food on the planet is only very loosely related to how many people get to eat. People starve to death today, not because the Earth doesn’t produce enough food, but because financial, geographic, and political problems keep food from getting to a lot of people. More people are obese today than starving. How many people can eat for how long under various carbon scenarios of the future will probably also have more to do with politics and money than global carrying capacity.
Finally, even in a fantasy where all petroleum use somehow does abruptly stop tomorrow, reduced global carrying capacity isn’t what kills people. What kills people in this scenario is not a reduction in food production but the failure of food transportation. About half the human population, maybe three and a half billion people, live in cities, according to a U.N. estimate. Some additional multitude live in rural areas but are likewise dependent on store-bought food. Without fossil fuel, most of those people would die, probably in panicked riots, long before global food reserves actually started to run low. Associated social instability would kill millions more. By the time the dust settled and the survivors started to pick up the pieces, overpopulation probably wouldn’t be a problem.
But I digress.
The point is that although some Hollywood-ready apocalypse is extremely unlikely (and would be only indirectly related to the end of oil if it did occur), the post-fossil-fuel world will not be a world of unlimited resources. We can live well without fossil fuels, and it is entirely possible that, due to further advances in technology, we will still be able to do and have most of the things fossil fuel gives us. Nevertheless, we will have less energy available to us than we have now.
Energy is not some vague thing that can be created or increased by wishing or by the right technology. In fact, energy cannot be created at all, nor can it be destroyed, although it does dissipate. These are the First and Second Laws of Thermodynamics. What they mean in practical terms is that if you have energy, whether that’s food in your belly or gas in your car, you must have got it from somewhere. And you’ll need to get more of it because as you use your energy you will lose some of it. Energy cannot be recycled. When it’s gone, it’s gone for good.
Because energy can be measured and because it follows predictable laws, scientists can follow it as it moves through systems. For example, if you know how much solar energy falls on a certain area of land and you know how efficient the grass there is at harvesting solar energy (it might get 10%), and you know how efficient a cow is at harvesting the energy in grass) then you can calculate how many pounds of cow you can get out of so many acres of grass. If you cut your pasture in half, you must cut your herd in half, too. Likewise, if you grow trees on your land instead of grass, you can calculate how many acres of sunlight you need to keep your house warm.
Of course, there are a lot of other factors involved with grasslands and forests, because ecology is fiendishly complex, but the amount of energy available provides an absolute limit on how much can grow where.
Prior to the Industrial Revolution, human activities were also limited by the amount of energy that falls on Earth from the sun. Food production, fuel to warm houses and make tools, feed for draft animals, wind to push sails, all were driven by the sun. Over time, we got better at harvesting this available energy and so the global population grew, but it grew slowly. The Industrial Revolution changed all that, triggering a dramatic increase in population; from the 1200’s through 1850, the world’s human population doubled perhaps every hundred and fifty to hundred years, but by 1950 global population had doubled again, this time in only a hundred years. Since 1950, as industrialization spreads over the world, humanity has almost tripled. In just sixty-four years.
While changes in economic structure, culture, and medicine have played a role in these increases, the most dramatic difference is that we have been using fossil fuel–harvesting the sunlight that fell on forests of fern and giant club-moss trees ages ago. It’s as though we made our pasture bigger than the planet actually is by grazing our cows on the fields of the past. So our herds got a lot bigger.
It can’t last. It won’t last. Climate change, environmental degradation, mass extinction of species, all of these are consequences of burning up the past, and though it may be possible to use fossil fuel less destructively than we have done, destruction is an inevitable consequence of altering the energy flow of an entire planet, as we have done. Our choice now is simply whether we will stop using fossil fuel voluntarily while we can still put some planning into the transition, or if we will instead wait until we are stopped by our planet’s response.
Without fossil fuel, our pastures will again shrink to the size of our present. Our herds and ourselves will have to shrink accordingly.
For a long time, now, we have lived with more. Various empires have expanded their influence, creating the illusion of ever more land for their own subjects. New technologies have allowed more extensive harvest of Earth’s resources, creating the illusion of more fish, more metal, more wood, etc. And fossil fuel use has created the illusion of more and more energy. Our culture, our public policy, even our economic theory is based on the principle that we are not limited by resource availability, only by our ingenuity at using and distributing those resources. And none of that is really true.
In one way or another, we’re going to have to wrap our minds around the concept of there is no more, and we’re going to have to do it soon. That means learning how to make touch choices fairly. It means redefining freedom and empowerment to mean not unfettered opportunity to grab as much as possible, but unfettered participation in the conversation about who gets what.
The world of the future will be different than the world of today. It won’t be as populous. It won’t be as rich in a material sense. Goods and people will, once again, move slowly. That doesn’t mean we’ll be transported back to the 1600’s; I expect we’ll have a solar-powered Internet, a small number of cars and trucks burning vegetable Diesel for use in emergencies, advanced medicine, and so forth. Our human ingenuity will ensure that we have enough.
The only thing we really have to give up–and this is not negotiable–is the belief that we can and should have more than enough.