The most recent issue of Scientific American (April, 2010) has a fascinating special report, titled "Boundaries for a Healthy Planet".
Opening the magazine to this article, I expected to find the usual treatise about Anthropogenic Global Warming (AGW--human-caused climate change), along with the usual proscriptions about the human behavior which need to be changed before it's too late--or, perhaps, that it's already too late.
Imagine my surprise when the article, while covering AGW, finds that there are far worse problems we have to deal with if we expect Earth to remain habitable for the human species.
A truncated version of the article can be found here; you can also get the full article by subscribing to the magazine, picking up a copy from your local newstand, or subscribing to the online digital version. For a summary of what the article is about, follow me over the jump.
According the the article, written by environmental scientist Jonathan Foley, the scientific community has defined nine environmental processes and the thresholds below which they must remain in order to keep the planet healthy.
They are:
- Land Use
- Freshwater Use
- Nitrogen and Phosphorus Cycles
- Ozone Depletion
- Ocean Acidification
- Climate Change
- Chemical Pollution
- Aerosol Loading
- Biodiversity Loss
Most of us are aware that Climate Change is already a problem: according to the consensus of the scientific community, the threshold for this process is determined mainly by CO2 concentration. Pre-industrial CO2 concentrations never went over 280 PPM, while current concentrations are 387 PPM. The boundary over which a serious problem can be said to occur? 350 PPM. No surprises there, though also no good news.
The surprises, though, come from what, to me, were unexpected areas.
Human-caused removal of nitrogen from the atmosphere, measured in millions of tons per year, had a pre-industrial value of 0, a current value of 133, and a threshold for action of 39!
Worse, the rate of biodiversity loss, in terms of species per million per year, had a pre-industrial value of 0.1 - 1.0, a current value estimated to be in excess of 100, and a threshold of 10. In other words, mankind is causing the extinction of species at a rate which is at least 100 times the historic average, and ten times higher than is considered "safe".
Other of the process areas are below threshold, but are still not good news:
Process |
Pre-industrial |
Current |
Threshold |
Land Use (% converted to cropland) |
Neglible |
11.7 |
15 |
Freshwater Use (cubic kilometers per year) |
415 |
2600 |
4000 |
Ocean Acidification (aragonite saturation state in surface water) |
3.44 |
2.90 |
2.75 |
Stratospheric Ozone Depletion (Dobson units) |
290 |
283 |
276 |
The only good news--perhaps? Aerosol loading and chemical pollution are shown in the article as being at "safe" levels--only because, for the moment, values are "to be determined".
A follow-up article in the same issue offers solutions (or at least palliatives) for the problem areas--none of which are easy or likely to go over easy with most people.
For instance, in the case of biodiversity loss, the articles cites three steps which must be taken:
- New science and tools to account for biodiversity in economic and other terms
- Compelling demonstrations of such tools
- Cooperation among governments, development organizations, corporations and communities to solve the problem
Any guess as to how difficult the third step will be?
An article well worth a full read to understand the range of issues we face as humans on the planet, where the problems lie, and what steps might be taken to avoid serious changes in how we live or, at worst, whether we live at all.