Saturday, September 29, 2012

Ecological overshoot and extinction debt

We have wiped out plenty of other animals. Ourselves as well?

With all the discussion of the Federal debt, another far more momentous debt is being ignored- the debts we are building up in the biosphere. Two papers discuss aspects of these debts, one about how to account for extinctions that have not happened yet, but which we have baked into the cake, and the other a general perspective on how badly we are living beyond our means overall.

Extinctions are extremely saddening to a biologist. They mark a loss of riches, of wealth, which is very unlikely to be made up. We are in the middle of one of the most severe extinction episodes in the history of life, entirely brought about by us. It will take tens of millions of years after our passing for earth to re-cover itself with new versions of the ecological complexity that humans have so greedily and thoughtlessly eradicated. That is, if we ever manage to give the biosphere any breathing space at all.

How bad is it? The paper on extinction debts, which focuses on the Amazon, notes that 80% of extinctions due to historical (past) habitat loss have yet to occur. This is because extinction takes some time to play out. When we are down to the last whimpering dodo bird, or carrier pigeon, or woodpecker, or condor, we are at the end of long process of habitat destruction, eradication, and ecological simplification.

Even if we care, it takes heroic efforts to keep such species on life support- efforts which often fail because there just isn't enough habitat left anywhere, or a lack of other conditions. The condor of Calfornia remains in doubtful condition because of continual destruction by electric wires and lead ammunition, among other problems, meaning that its status is by no means assured. And with the extremely small population sizes possible after even this effort, the long-term genetic prospects of such species remain quite bleak. Other vultures are in even worse condition.

No, the way to save species is to actually save habitat, on large scales and protected conditions that preserve the compelete ecosystems on which those species depend. Here is their estimate of extinctions in the Amazon, under business as usual conditions, only among vertebrate species:

Turning to humans, how bad is it for us? Even if we deny any moral or aesthetic interest in the preservation of other species, we are a species too, and we have been generating a debt of our own, eating ourselves out of house and home. The other paper (from 2002) catalogs humanity's consumption of various biosphere services, and concludes that we are using more (1.2 fold more at the time) earths than we currently occupy, suggesting that in the business-as-usual future, we will not only see our growth slowed, but will see a sharp reduction in living standards and/or population levels, due to the ecological overshoot we are currently committing. As with extinction debts, the full cost of over-consumption can take time to show up, with a population crash the typical result.

Our living standards have already been going down for some time. My run-of-the-mill house is made of extremely dense timber that would be virtually unobtainable today. Typical construction timber is no longer old-growth, but plantation-grown pine and fir that resemble balsa wood more than oak. Fish are smaller and scarcer, with many stocks utterly fished out. Peak oil is here, and price pressures are starting, ever so slowly, to change US living habits.

The researchers looked at our gross areas of environmental impact- farming, livestock raising, timber cutting, fishing, land use for habitation and industry, and CO2 emission. We use 0.28 earths for farming, 0.15 earths for timber harvesting, and 0.61 earths for our unsustainable CO2 emission. We use 0.18 earths for the other categories, totalling to well over one earth overall- numbers that have surely grown as Asian economies have developed pell mell.

Now, this computation is a bit fanciful, mostly a way to talk about the unsustainability of our current practices. Economics would claim that we can smoothly substitute or innovate our way out of any critical shortages. But the end of a fish stock is really an end. Our living standard goes down with every loss of this kind, both in market/consumption terms, and also in aesthetic terms. It goes down as well in unexpected ways as ecosystems that serve us become simplified, for instance as the oceans turn into seas of jellies and garbage, rather than the fabulously rich seas our ancestors enjoyed. It was a garden of Eden, indeed!

It is hard to forecast the future. We know for sure that we are already beyond the sustainable capacity of the planet, and are going way beyond it in the business-as-usual scenario. The issues extend far beyond land use, atmospheric pollution and biosphere degradation to water use, the availability of obscure minerals like lithium and helium, radioactive and other forms of toxic waste, ocean acidification, an epidemic of exotic species invasions, ... the list of overuse is endless.

As animals, we are programmed to reproduce as much as possible. The typical limits to biological reproduction have been disease, competition, and starvation. Humanity has made wonderful strides in escaping each of these limits by technological and social progress. It has truly been an astonishing and world-shaking accomplishment. But if our consciousness and organizational solutions do not rise to the next level of engagement with our long-term sustainability constraints, we will not only be poorer in the future in countless small ways, but may face another dark age, as we play out a massive ecological boom and bust cycle.

  • Morsi tells us to correct the Palestinian situation, and he is right. (CSPAN)
  • Group is spelled g*o*d. Mormon groupishness, cont.
  • Muhammed = god as well. Islam seems essentially bi-deistic, as Christianity is tri-deistic or more.
  • China: model for union-busting Republicans.
  • Germany's export prowess rests mostly on underpaying its workers, and the surplus is wasted on loans to other countries.
  • Speaking of which, European internal trade imbalances continue apace. Nothing real is being done.

  • Economic production and class structure, in flux.
  • Crocker on past policy.. harsh on Bush, soft on Pakistan.
  • MMT godfather Godley described the current crisis in 1992: "If a country or region has no power to devalue, and if it is not the beneficiary of a system of fiscal equalisation, then there is nothing to stop it suffering a process of cumulative and terminal decline leading, in the end, to emigration as the only alternative to poverty or starvation."


  1. Good post! How do you think birth control and education fit into the human population question? My own thoughts are here:

  2. Hi, JD-

    Thanks for the question and your post. I take a more pessimistic attitude, because whatever population we end up with, we have already degraded our biosphere and are degrading it more daily. So we end up poorer however many or few we are.

    Education is a double edged sword, because while it strongly moderates population growth, it also promotes development and higher consumption. As things stand, the world population is already set to plateau- that is already baked in the cake of worldwide demographics, as birth rates fall all over the world. We will top out around 10-12 billion or so, from what I understand. There is no reason to think that we will ever exceed that, since all the more developed societies are heading downwards in population growth.

    Yet it is all already way too much, and the only way to save valuable aspects of the biosphere, let alone our developed energy-intensive way of life, is to take conscious control of reducing our consumption, which is the opposite of "drill, baby drill". It is unacceptable to wait around for fossil energy extraction prices/costs to dictate our relationship with the ecosystem. We need to raise prices immediately in ways that put us on a sustainable footing.