Overshoot has two components, resource depletion and waste buildup. Anthropogenic GW is proof positive that we're in overshoot. As a species we've been able to ramp our total consumption up so high (and avoid the consequences for so long) because of our one-time gift of fossil fuels. I say the following in the
"Overshoot" section of my article
World Energy and Population:
There are two ways a population in overshoot can regain its balance with the carrying capacity of its environment. If the population stays constant or continues rising, its activity (expressed in terms of per capita resource consumption and waste production) must fall. If per capita consumption stays constant, population numbers must decline.
Populations in serious overshoot always decline. This is seen in wine vats when the yeast cells die after consuming all the sugar from the grapes and bathing themselves in their own poisonous alcoholic wastes. It's seen in predator-prey relations in the animal world, where the depletion of the prey species results in a reduction in the number of predators. This population reduction is known as a crash or a die-off, and can be very rapid.
Figure 15: Overshoot
It is an axiom of ecology that overshoots degrade the carrying capacity of the environment. This is illustrated in the declining "Carrying Capacity" curve in Figure 15. In the case of humanity, our use of oil has allowed us to perform prodigious feats of resource extraction and waste production that would simply have been inconceivable without the one-time gift of oil. Fossil fuels in general and oil in particular have made it possible for humanity to stay in a state of overshoot for a long time.
At the same time, the use of fossil fuel and other high-intensity energy has allowed us to mask the underlying degradation of the Earth's carrying capacity. For instance, the loss of arable land and topsoil fertility (estimated at 30% or more since World War II) has been masked by the use of artificial fertilizers made largely from natural gas. Another example is the death of the oceans, where 90% of all large fish species are now at risk, and most fish species will be at risk within 40 years. This situation would be calamitous for nations that depend on the oceans for food, except that the use of fossil fuels allow them to fish ever farther from their home waters or import non-oceanic food to make up for the shortage of fish. Depleted water tables can be supplemented by water pumped from deeper wells; air pollution can be avoided by the use of air conditioners, etc. All of these indicate that ecological decline is being conveniently masked by our use of energy.
As our supply of energy (and especially that one-time gift of fossil fuels) begins to decline, this mask will be gradually peeled away to reveal the true extent of our ecological depredations. As we have to rely more and more on the unassisted bounty of nature, the consequences of our actions will begin to affect us all.
When you tie this observation about the unmasking of our overshoot together with the drastically unequal global distribution of energy, GDP and population growth I explored in
World Energy to 2050 and
Energy Decline and the Growth of Destitution, the shape of things to come clarifies a bit.
First, it's obvious that the most severe effects of overshoot will be felt in Africa and South Asia. Those regions are vulnerable to every aspect of overshoot. Global warming will affect them strongly through droughts and floods, which will act to reduce their already marginal or deficient food production. Disproportionately lower energy supplies mean they will not be able to mask those effects by using more fertilizer, importing and distributing food, or finding alternate food sources like distant corners of the ocean that still have fish. The reduced GDP that comes with less energy will make it harder for them to afford mitigating technologies like wind turbines or desalination plants. The decline in natural gas will make fertilizer more expensive, reducing its use and cutting crop yields even further.
Let's look just at Africa. There is an
ominous report from the FAO and the IPCC (notably un-hysterical organizations) which concludes that Africa could lose half its food supply by 2020. They point out that 95 percent of Africa’s agriculture depends on rainfall. They worry that that crop revenues in Africa could fall by as much as 90 percent by 2100 and that wheat production is "likely" to disappear from Africa by the 2080s.
As far as I know, these scientists are just looking at climate change, and have not factored in the rising fertilizer prices that are already impacting African farmers. In Malawi, for example, a famine situation was recently turned around when the government stepped in with a 75% subsidy of nitrogen fertilizers. As natural gas prices rise around the world, they will take fertilizer prices with them, since
85% of the cost of fertilizer is the cost of the natural gas feedstock. A tripling of the world average fertilizer price over the next decade or two doesn't seem outside the realm of possibility, given that it has already
http://www.neo.ne.gov/statshtml/181.htm">doubled in the last 5 years.
These two factors of droughts and fertilizer shortages converge with the continuing impoverishment of the African population I described in my article
Energy Decline and the Growth of Destitution" That impoverishment will leverage the effect of fertilizer and fuel price increases for African farmers, driving those essentials ever further out of reach. It appears likely that Africa is indeed headed for an overall 50% shortfall in agricultural output before the middle of the century.
The bad news for Africa doesn't stop there, though. Their population is expected to double by 2050, leaving the absurd image of a continent of 1.5 billion people trying to survive on a mere quarter of the per capita food they are consuming today. Obviously such a scenario in unrealistic, and something will have to give. If the projections for food production are accurate, the weak link will have to be the population.
Here's a site with a sobering collection of facts:
http://www.un.org/ecosocdev/geninfo/afrec/vol20no2/202-boosting-farm-yields.html">Boosting African farm yields
Africa uses about 1/10 the fertilizer per hectare of industrialized countries (21 kg/ha vs. 206 kg/ha). That means that their grain yield per hectare is a third that of the rich nations.
Heavy reliance on imported fertilizers, combined with high transportation costs and the absence of suppliers in the countryside, has meant that African farmers pay between two and six times the average world price for fertilizer — when they can find it at all. The IFDC study estimated that it costs more to move a kilogramme of fertilizer from an African port to a farm 100 kilometres inland than it costs to move it from a factory in the US to the port. With millions of African family farmers surviving on less than a dollar a day, imported fertilizer is simply unaffordable.
And,
Citing the potential environmental risks to African soils and water sources from too much chemical fertilizer being applied to farms — as sometimes happened during Asia’s “green revolution” — proponents of sustainable agriculture in Africa argue that farmers should use more animal manure, compost and other organic fertilizers. If farmers better integrate stock-raising with crop cultivation, cattle and other livestock could provide them with not only more manure but also with animal traction for ploughing fields and hauling crops after they are harvested.
While organic fertilizers are important, agrees Mr. Roy, he points to a serious limitation. “The quality of animal manure is dependent on the quality of the food the animals are fed.” With much soil severely depleted, he says, “the fodder contains little of the nutrients needed by crops.” Organic fertilizers alone “are simply not the answer to the crisis of Africa’s soil fertility. We need to increase the use of both organic and chemical fertilizers.”
Will we actually see a halving of Africa's population within the next 40 years? If the demographers, climate scientists and agronomists are correct, we probably will. It seems to me that this identifies the triggering locus of the coming global population decline.
The same effects will follow along in South Asia, probably trailing those in Africa by no more than a decade. Waves of economic refugees will wash across Africa, Asia and Europe. At the height of the migrations perhaps a billion people will be displaced, with all the violence, misery and geopolitical instability that implies.
The rich West will do fine, relatively speaking. We have the money to outbid the poor nations for the energy supplies we need. That will allow us to retain more of the "overshoot mask" I mentioned above, at least for a while. The problem for the West will be transportation, which will ultimately destabilize our economies. The transportation troubles could begin within a decade and progress quite rapidly as the net oil export problem dries up the international oil market by 2035.
Relative to the troubles in Africa and Asia, our difficulties will be minor, though they won't seem like it to us. Like Africa and Asia will see a drop in food supplies, both through spreading droughts and competition from biofuels. I think we will see food prices in North America rise to ten or twenty times their current levels within 25 years. At that point, weakened by resource wars, short on food and fuel, with our medical and urban sanitation infrastructure ravaged by global depression, we will finally start to succumb to our own population reduction by 2050.
That's sort of how I think it will look.
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