gregory_benford's picture
Emeritus Professor of Physics and Astronomy, UC-Irvine; Novelist, The Berlin Project
Think outside the Kyoto box

Few economists expect the Kyoto Accords to attain their goals. With compliance coming only slowly and with three big holdouts — the US, China and India — it seems unlikely to make much difference in overall carbon dioxide increases. Yet all the political pressure is on lessening our fossil fuel burning, in the face of fast-rising demand.

This pits the industrial powers against the legitimate economic aspirations of the developing world — a recipe for conflict.

Those who embrace the reality of global climate change mostly insist that there is only one way out of the greenhouse effect — burn less fossil fuel, or else. Never mind the economic consequences. But the planet itself modulates its atmosphere through several tricks, and we have little considered using most of them. The overall global problem is simple: we capture more heat from the sun than we radiate away. Mostly this is a good thing, else the mean planetary temperature would hover around freezing. But recent human alterations of the atmosphere have resulted in too much of a good thing.

Two methods are getting little attention: sequestering carbon from the air and reflecting sunlight.

Hide the Carbon

There are several schemes to capture carbon dioxide from the air: promote tree growth; trap carbon dioxide from power plants in exhausted gas domes; or let carbon-rich organic waste fall into the deep oceans. Increasing forestation is a good, though rather limited, step. Capturing carbon dioxide from power plants costs about 30% of the plant output, so it's an economic nonstarter.

That leaves the third way. Imagine you are standing in a ripe Kansas cornfield, staring up into a blue summer sky. A transparent acre-area square around you extends upwards in an air-filled tunnel, soaring all the way to space. That long tunnel holds carbon in the form of invisible gas, carbon dioxide — widely implicated in global climate change. But how much?

Very little, compared with how much we worry about it. The corn standing as high as an elephant's eye all around you holds four hundred times as much carbon as there is in man-made carbon dioxide — our villain — in the entire column reaching to the top of the atmosphere. (We have added a few hundred parts per million to our air by burning.) Inevitably, we must understand and control the atmosphere, as part of a grand imperative of directing the entire global ecology. Yearly, we manage through agriculture far more carbon than is causing our greenhouse dilemma.

Take advantage of that. The leftover corn cobs and stalks from our fields can be gathered up, floated down the Mississippi, and dropped into the ocean, sequestering it. Below about a kilometer depth, beneath a layer called the thermocline, nothing gets mixed back into the air for a thousand years or more. It's not a forever solution, but it would buy us and our descendents time to find such answers. And it is inexpensive; cost matters.

The US has large crop residues. It has also ignored the Kyoto Accord, saying it would cost too much. It would, if we relied purely on traditional methods, policing energy use and carbon dioxide emissions. Clinton-era estimates of such costs were around $100 billion a year — a politically unacceptable sum, which led Congress to reject the very notion by a unanimous vote.

But if the US simply used its farm waste to "hide" carbon dioxide from our air, complying with Kyoto's standard would cost about $10 billion a year, with no change whatsoever in energy use.
The whole planet could do the same. Sequestering crop leftovers could offset about a third of the carbon we put into our air.

The carbon dioxide we add to our air will end up in the oceans, anyway, from natural absorption, but not nearly quickly enough to help us.

Reflect Away Sunlight

Hiding carbon from air is only one example of ways the planet has maintained its perhaps precarious equilibrium throughout billions of years. Another is our world's ability to edit sunlight, by changing cloud cover.

As the oceans warm, water evaporates, forming clouds. These reflect sunlight, reducing the heat below — but just how much depends on cloud thickness, water droplet size, particulate density — a forest of detail.

If our climate starts to vary too much, we could consider deliberately adjusting cloud cover in selected areas, to offset unwanted heating. It is not actually hard to make clouds; volcanoes and fossil fuel burning do it all the time by adding microscopic particles to the air. Cloud cover is a natural mechanism we can augment, and another area where possibility of major change in environmental thinking beckons.

A 1997 US Department of Energy study for Los Angeles showed that planting trees and making blacktop and rooftops lighter colored could significantly cool the city in summer. With minimal costs that get repaid within five years we can reduce summer midday temperatures by several degrees. This would cut air conditioning costs for the residents, simultaneously lowering energy consumption, and lessening the urban heat island effect. Incoming rain clouds would not rise as much above the heat blossom of the city, and so would rain on it less. Instead, clouds would continue inland to drop rain on the rest of Southern California, promoting plant growth. These methods are now under way in Los Angeles, a first experiment.

We can combine this with a cloud-forming strategy. Producing clouds over the tropical oceans is the most effective way to cool the planet on a global scale, since the dark oceans absorb the bulk of the sun's heat. This we should explore now, in case sudden climate changes force us to act quickly.
Yet some environmentalists find all such steps suspect. They smack of engineering, rather than self-discipline. True enough — and that's what makes such thinking dangerous, for some.

Yet if Kyoto fails to gather momentum, as seems probable to many, what else can we do? Turn ourselves into ineffectual Mommy-cop states, with endless finger-pointing politics, trying to equally regulate both the rich in their SUVs and Chinese peasants who burn coal for warmth? Our present conventional wisdom might be termed The Puritan Solution — Abstain, sinners! — and is making slow, small progress. The Kyoto Accord calls for the industrial nations to reduce their carbon dioxide emissions to 7% below the 1990 level, and globally we are farther from this goal every year.

These steps are early measures to help us assume our eventual 21st Century role, as true stewards of the Earth, working alongside Nature. Recently Billy Graham declared that since the Bible made us stewards of the Earth, we have a holy duty to avert climate change. True stewards use the Garden's own methods.