(This is Part 2 of a series. Go back to Part 1.)
1. The human assault on nature
If we're to talk about the most important "news" of the day, we must put this first. The reason is that there is no "Plan B" planet. This is the only one we've got, and it's becoming quite ill, complete with a rising fever.
The usual litany: Extinction of species, "The Sixth Great Extinction" according to scientists. Pollution of rivers, lakes and shorelines with pesticides, dioxins and heavy metals. Melting ice caps everywhere. Collapse of global fisheries. Slowing of the Gulf Stream. Increasing droughts, flooding and erratic weather. An ozone hole the size of a continent. Pollution of the air with carbon, methane and sulfur dioxide. Acidifying the oceans. Extreme deforestation. Need I go on?
There's a famous experiment, astonishing in its conclusion, where a frog is placed in a pan of water that is slowly brought to boiling. If the water is heated slowly enough, the frog never jumps out.
That is our situation. The destruction of the biosphere—a thin planetary layer, comparable to the skin of an apple, in which all life occurs—is happening slowly enough that it hasn't really grabbed our attention. We recently had mid-term elections in the United States, and yet during the campaign the environment was hardly mentioned. There were other, more dramatic things to talk about, like the Iraq War, the Middle East, terrorism, deficits, energy security and so on.
All of those things are important, but they pale in importance to the degradation of the planet. Our planet's ecological decline is what the brilliant analyst Thomas Homer-Dixon calls a slow-creep problem—something that comes on slowly enough, like the rising temperature of the water in the pan, that it doesn't strongly capture our attention.
Our nervous systems are wired to notice changes in our environment. The faster the change is happening, the more it compels our attention. After all, that's how we notice the lion stepping out of the foliage. And if the change is fast enough to be dramatic, even better: our attention is riveted. Every newscaster knows that, every filmmaker who ever blew up something onscreen knows that. Meanwhile, it can be hard to work up much alarm about slow-creep problems.
Where the environment is concerned, we tend to assume that warming, degradation, etc. work in a linear fashion—that is, that they'll continue to get worse in a gradual, linear way. But two factors undermine that complacent assumption:
The first factor is that the world's climate system, and its biosphere in general, are non-linear systems. In a non-linear system, small changes can sometimes create large effects when a threshold or tipping point is suddenly crossed.
An example of such a non-linear effect is the slow buildup of tectonic stresses that precedes an earthquake. As two tectonic plates build up stresses against other, nothing may seem amiss for many years until a threshold is crossed one day and the stress is suddenly released in an earthquake. Until then everything seems normal. There are a number of such potential tipping points in the global climate and the ecology, points where the nature of these systems could suddenly change in a dramatic way.
The second factor that could suddenly precipitate us into a whole different situation is the potential for positive feedback. This is a phenomenon that occurs when a process begins to reinforce itself, creating a runaway effect.
One example out of many is that ice tends to reflect light and heat, whereas open water tends to absorb it. As vast ice sheets in the Arctic and elsewhere melt, the resulting increase in areas of open water speed up the heating process, which then melts even more ice and so on.
A second example is the methane frozen in huge tracts of permafrost in Siberia, Alaska and western Canada. Methane is a particularly virulent greenhouse gas, many time more virulent than carbon dioxide. As the planet continues to heat, this permafrost could begin to melt—releasing vast quantities of methane into the atmosphere, which then creates further melting of the permafrost and further release of methane, etc.
Humanity would be wise not to find out what happens after such tipping points are crossed and such runaway effects occur. We would be wise to act now, when the degradation of the planet's biosphere still appears to us as a slow-creep situation.
(This is the end of Part 2. Go to Part 3.)
—jim sloman, 11.28.06
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