Over the next year or so, as I’ve mentioned in recent posts,
I plan on tracing out as much as possible of what can be known or reasonably
guessed about the next five hundred years or so of North American history—the
period of the decline and fall of the civilization that now occupies that
continent, the dark age in which that familiar trajectory ends, and the first
stirrings of the successor societies that will rise out of its ruins. That’s a
challenging project, arguably more so than anything else I’ve attempted here,
and it also involves some presuppositions that may be unfamiliar even to my
regular readers.
To begin with, I’m approaching history—the history of the
past as well as of the future—from a strictly ecological standpoint. I’d like to propose, in fact, that history
might best be understood as the ecology of human communities, traced along the
dimension of time. Like every other
ecological process, in other words, it’s shaped partly by the pressures of the
senvironment and partly by the way its own subsystems interact with one
another, and with the subsystems of the other ecologies around it. That’s not a
common view; most historical writing these days puts human beings at the center of the picture, with the
natural world as a supposedly static background, while a minority view goes to
the other extreme and fixates on natural catastrophes as the sole cause of this
or that major historical change.
Neither of these approaches seem particularly useful to me.
As our civilization has been trying its level best not to learn for the last
couple of centuries, and thus will be learning the hard way in the years
immediately ahead, the natural world is not a static background. It’s an active
and constantly changing presence that responds in complex ways to human
actions. Human societies, in turn, are equally active and equally changeable,
and respond in complex ways to nature’s actions. The strange loops generated by
a dance of action and interaction along these lines are difficult to track by
the usual tools of linear thinking, but they’re the bread and butter of systems
theory, and also of all those branches of ecology that treat the ecosystem
rather than the individual organism as the basic unit.
The easiest way to show how this perspective works is to
watch it in action, and it so happens that one of the most important factors
that will shape the history of North America over the next five centuries is
particularly amenable to a systems analysis. The factor I have in mind is climate.
Now of course that’s also a political hot potato just at the
moment, due to the unwillingness of a great many people across the industrial
world to deal with the hard fact that they can’t continue to enjoy their
current lifestyles if they want a climatically and ecologically stable planet
to live on. It doesn’t matter how often the planet sets new heat records, nor
that the fabled Northwest Passage around the top end of Canada—which has been
choked with ice since the beginning of recorded history—is open water every
summer nowadays, and an increasingly important route for commercial shipping
from Europe to the eastern shores of Asia; every time the planet’s increasingly
chaotic weather spits out unseasonably cold days in a few places, you can count
on hearing well-paid flacks and passionate amateurs alike insisting at the top
of their lungs that this proves that anthropogenic climate change is nonsense.
To the extent that this reaction isn’t just propaganda, it
shows a blindness to systems phenomena I’ve discussed here before: a learned inability to recognize that change
in complex systems does not follow the sort of nice straight lines our current
habits of thought prefer. A simple experiment can help show how complex systems
respond in the real world, and in the process make it easier to make sense of
the sort of climate phenomena we can count on seeing in the decades ahead.
The next time you fill a bathtub, once you’ve turned off the
tap, wait until the water is still. Slip your hand into the water, slowly and
gently, so that you make as little disturbance in the water as possible. Then
move your hand through the water about as fast as a snail moves, and watch and
feel how the water adapts to the movement, flowing gently around your hand. .
Once you’ve gotten a clear sense of that, gradually increase
the speed with which your hand is moving. After you pass a certain threshold of
speed, the movements of the water will take the form of visible waves—a bow
wave in front of your hand, a wake behind it in which water rises and falls
rhythmically, and wave patterns extending out to the edges of the tub. The
faster you move your hand, the larger the waves become, and the more visible
the interference patterns as they collide with one another.
Keep on increasing the speed of your hand. You’ll pass a
second threshold, and the rhythm of the waves will disintegrate into
turbulence: the water will churn, splash, and spray around your hand, and
chaotic surges of water will lurch up and down the sides of the tub. If you
keep it up, you can get a fair fraction of the bathwater on your bathroom
floor, but this isn’t required for the experiment! Once you’ve got a good sense
of the difference between the turbulence above the second threshold and the
oscillations below it, take your hand out of the water, and watch what happens:
the turbulence subsides into wave patterns, the waves shrink, and finally—after
some minutes—you have still water again.
This same sequence of responses can be traced in every
complex system, governing its response to every kind of disturbance in its
surroundings. So long as the change stays below a certain threshold of
intensity and rapidity—a threshold that differs for every system and every kind
of change—the system will respond smoothly, with the least adjustment that will
maintain its own internal balance. Once that threshold is surpassed,
oscillations of various kinds spread through the system, growing steadily more
extreme as the disturbance becomes stronger, until it passes the second
threshold and the system’s oscillations collapse into turbulence and chaos.
When chaotic behavior begins to emerge in an oscillating system, in other
words, that’s a sign that real trouble may be sitting on the doorstep.
If global temperature were increasing in a nice even line,
in other words, we wouldn’t have as much to worry about, because it would be
clear from that fact that the resilience of the planet’s climate system was
well able to handle the changes that were in process. Once things begin to
oscillate, veering outside usual conditions in both directions, that’s a sign
that the limits to resilience are coming into sight, with the possibility of
chaotic variability in the planetary climate as a whole waiting not far beyond
that. We can fine-tune the warning signals a good deal by remembering that
every system is made up of subsystems, and those of sub-subsystems, and as a
general rule of thumb, the smaller the system, the more readily it moves from
local adjustment to oscillation to turbulence in response to rising levels of
disturbance.
Local climate is sensitive enough, in fact, that ordinary
seasonal changes can yield minor turbulence, which is why the weather is so
hard to predict; regional climates are more stable, and normally cycle through
an assortment of wavelike oscillations; the cycle of the seasons is one, but
there are also multiyear and multidecade cycles of climate that can be tracked
on a regional basis. It’s when those regional patterns start showing chaotic
behavior—when, let’s say, the usually sizzling Texas summer is suddenly broken
by a record cold snap in the middle of July, in a summer that’s shaping up globally to
be among the hottest ever measured—that you know the whole system is coming
under strain.
I’m not generally a fan of Thomas Friedman, but he scored a
direct hit when he warned that what we have to worry about from anthropogenic
climate change is not global warming but "global weirding:" in the
terms I’ve used in this post, the emergence of chaotic shifts out of a global
climate that’s been hit with too much disturbance too fast. A linear change in
global temperatures would be harsh, but it would be possible to some extent to
shift crop belts smoothly north in the northern hemisphere and south in the
southern. If the crop belts disintegrate—if you don’t know whether the next season
is going to be warm or cold, wet or dry, short or long—famines become hard to
avoid, and cascading impacts on an already strained global economy add to the
fun and games. At this point, for the
reasons just shown, that’s the most likely shape of the century or two ahead of
us.
In theory, some of that could be avoided if the world’s
nations were to stop treating the skies as an aerial sewer in which to dump
greenhouse gases. In practice—well, I’ve met far too many climate change
activists who still insist that they have to have SUVs to take their kids to
soccer practice, and I recall the embarrassed silence that spread a while back
when an important British climate scientist pointed out that maybe jetting all
over the place to climate conferences was communicating the wrong message at a
time when climate scientists and everyone else needed to decrease their carbon
footprint. Until the people who claim to be concerned about climate change
start showing a willingness to burn much less carbon, it’s unlikely that anyone
else will do so, and so I think it’s a pretty safe bet that fossil fuels will
continue to be extracted and burnt as long as geological and economic realities
permit.
The one bleak consolation here is that those realities are a
good deal less flexible than worst-case scenarios generally assume. There are
two factors in particular to track here, and both unfold from net energy—the
difference between the energy content of fossil fuels as they reach the end
consumer and the energy input needed to get them all the way there. The first
factor is simply that if a deposit of fossil carbon takes more energy to
extract, process, and transport to the end user than the end user can get by
burning it, the fossil carbon will stay in the ground. The poster child here is
kerogen shale, which has been the bane of four decades of enthusiastic energy
projects in the American West and elsewhere. There’s an immense amount of
energy locked up in the Green River shale and its equivalents, but every
attempt to break into that cookie jar has come to grief on the hard fact that,
all things considered, it takes more energy to extract kerogen from shale than
you get from burning the kerogen.
The second factor is subtler and considerably more damaging.
As fossil fuel deposits with abundant net energy are exhausted, and have to be
replaced by deposits with lower net energy, a larger and larger fraction of the
total energy supply available to an industrial society has to be diverted from
all other economic uses to the process of keeping the energy flowing. Thus it’s not enough to point to high total
energy production and insist that all’s well; the logic of net energy has to be
applied here as well, and the total energy input to energy production,
processing, and distribution subtracted from total energy production, to get a
realistic sense of how much energy is available to power the rest of the
economy—and the rest of the economy, remember, is what produces the wealth that
makes it possible for individuals, communities, and nations to afford fossil
fuels in the first place.
Long before the last
physically extractable deposit of fossil fuel is exhausted, in other words,
fossil fuel extraction will have to stop because it’s become an energy sink
rather than an energy source. Well before that point is reached, furthermore,
the ability of global and national economies to meet the energy costs of fossil
fuel extraction will slam face first into hard limits. Demand destruction,
which is what economists call the process by which people who can’t afford to
buy a product stop using it, is as important here as raw physical depletion; as
economies reel under the twin burdens of depleting reserves and rising energy
costs for energy production, carbon footprints will shrink willy-nilly as rapid
downward mobility becomes the order of the day for most people.
Combine these factors with the economic impacts of
"global weirding" itself and you’ve got a good first approximation of
the forces that are already massing to terminate the fossil fuel economy with
extreme prejudice in the decades ahead. How those are likely to play out the
future we’re facing will be discussed at length in several future posts. For
the time being, I’ll just note that I expect global fossil fuel consumption and
CO2 emissions to peak within a decade or so to either side of 2030, and then
tip over into a ragged and accelerating decline, punctuated by economic and
natural disasters, that will reach the zero point of the scale well before
2100.
What that means for the future climate of North America is
difficult to predict in detail but not so hard to trace in outline. From now
until the end of the 21st century, perhaps longer, we can expect climate chaos,
accelerating in its geographical spread and collective impact until a couple of
decades after CO2 emissions peak, due to the lag time between when greenhouse
gases hit the atmosphere and when their effects finally peak. As the rate of
emissions slows thereafter, the turbulence will gradually abate, and some time
after that—exactly when is anybody’s guess, but 2300 or so is as good a guess
as any—the global climate will have settled down into a "new normal"
that won’t be normal by our standards at all. Barring further curveballs from
humanity or nature, that "new normal" will remain until enough excess
CO2 has been absorbed by natural cycles to matter—a process that will take
several millennia at least, and therefore falls outside the range of the five
centuries or so I want to consider here.
An educated guess at the shape of the "new normal"
is possible, because for the last few million years or so, the paleoclimatology
of North America has shown a fairly reliable pattern. The colder North America
has been, by and large, the heavier the rainfall in the western half of the
continent. During the last Ice Age, for example, rainfall in what’s now the
desert Southwest was so heavy that it produced a chain of huge pluvial (that
is, rain-fed) lakes and supported relatively abundant grassland and forest
ecosystems across much of what’s now sagebrush and cactus country. Some measure of the difference can be caught
from the fact that 18,000 years ago, when the last Ice Age was at its height,
Death Valley was a sparkling lake surrounded by pine forests. By contrast, the
warmer North America becomes, the dryer the western half of the continent gets,
and the drying effect spreads east a very long ways.
After the end of the last Ice Age, for example, the world
entered what nowadays gets called the Holocene Climatic Optimum; that term’s a
misnomer, at least for this continent, because conditions over a good bit of
North America then were optimum only for sand fleas and Gila monsters. There’s
been a running debate for several decades about whether the Hypsithermal, to
use the so-called Optimum’s other name, was warmer than today all over the
planet or just in some regions. Current
opinion tends to favor the latter, but the difference doesn’t actually have
that much impact on the issue we’re considering: the evidence from a broad range of sources
shows that North America was significantly warmer in the Hypsithermal than it
is today, and so that period makes a fairly good first approximation of the
conditions this continent is likely to face in a warmer world.
To make sense of the long-term change to North American
climates, it’s important to remember that rainfall is far more important than
temperature as a determining factor for local ecosystems. If a given region
gets more than about 40 inches of rain a year, no matter what the temperature,
it’ll normally support some kind of forest; if it gets between 40 and 10 inches
a year, you’ve got grassland or, in polar regions, mosses and lichens; if you
get less than 10 inches a year, you’ve got desert, whether it’s as hot as the
Sahara or as bitterly cold as the Takla Makan. In the Hypsithermal, as the west
dried out, tallgrass prairie extended
straight across the Midwest to western Pennsylvania, and much of the Great
Plains were desert, complete with sand dunes.
In a world with ample fossil fuel supplies, it’s been
possible to ignore such concerns, to the extent of pumping billions of gallons
of water a year from aquifers or distant catchment basins to grow crops in
deserts and the driest of grasslands, but as fossil fuel supplies sunset out,
the shape of human settlement will once again be a function of annual rainfall,
as it was everywhere on the planet before 1900 or so. If the Hypsithermal’s a
valid model, as seems most likely, most of North America from the Sierra Nevada
and Cascade ranges east across the Great Basin and Rocky Mountains to the Great
Plains will be desert, as inhospitable as any on Earth, and human settlement
will be accordingly sparse: scattered towns in those few places where geology
allows a permanent water supply, separated by vast desolate regions inhabited
by few hardy nomads or by no one at all.
East of the Great Desert, grassland will extend for a
thousand miles or more, east to the
Allegheny foothills, north to a thinner and dryer boreal forest belt
shifted several hundred miles closer to the Arctic Ocean, and south to the
tropical jungles of the Gulf coast. Further south, in what’s now Mexico, the
tropical rain belt will move northwards with shifts in the global atmospheric
circulation, and the Gulf coast east of the Sierra Madre Oriental will shift to
tropical ecosystems all the way north to, and beyond, the current international
border. Between the greatly expanded tropical zone in the south and east and
the hyperarid deserts of the north, Mexico will be a land of sharp ecological
contrasts
Factor in sea level rise, on the one hand, and the long-term
impacts of soil depletion and of toxic and radioactive wastes on the
other—issues complicated enough in their causes, trajectory, and results that
they’re going to require separate posts—and you’ve got a fairly limited set of
regions in which agriculture will be possible in a post-fossil fuel
environment: basically, the eastern seaboard from the new coast west to the
Alleghenies and the Great Lakes, and river valleys in the eastern half of the
Mississippi basin. The midwestern grasslands will support pastoral grazing, and
the jungle belts around the new Gulf coast and across southern Mexico will be
suitable for tropical crops once the soil has a chance to recover, but the
overall human carrying capacity of the continent will be significantly smaller
than it was before the industrial age began.
