GREGORY BENFORD Department of Physics & Astronomy University of California, Irvine
Our biosphere and geosphere do not respond on the time scales of our institutions. Climate change makes this clear. Humanity has never confronted a problem of this kind or magnitude before, and we cannot know how long it will take us to respond to the two major threats we can now see: · increasing climate change, driven at a high rate by global warming. · the rise in acid levels in our ocean, already well documented
There certainly will be further threats, as our numbers and influences grow. But at this early stage, in an era that will probably last centuries, we cannot know them all. We do not understand our world well enough. But we cannot simply delay.
We should accept the possibility that anthropogenic carbon emissions could trigger a climactic tripping point, such as interruption of the Gulf Stream in the Atlantic. To avoid this, current thinking urges an all-out effort to shrink the human atmospheric-carbon footprint. But many energy authorities believe this task will take a century or more. Our fossil fuel burning is accelerating, not declining.
So we should also consider relatively low tech, low expense experiments, to accelerate our understanding of climate science. These could lead to restoring the climate we prefer. This means changing the climate on purpose instead of by mistake, as we are doing now. Smart changes could return us to our earlier, milder world.
Focusing First on the Arctic
The two clear threats above develop over different time scales. Very roughly, ocean acidification is growing over times like fifty years, as presently observed. The oceans circulate well, so the effects spread around the globe quite evenly.
We think of global warming as an effect in our atmosphere, since carbon dioxide builds up there. But the atmospheric warming also heats the oceans. This warming is not uniform, though, for many complex reasons. Sunlight falls most weakly in the Arctic and Antarctic, yet these areas show the greatest rate of change due to air and ocean warming.
In the Arctic particularly, the warmer ocean melts ice, exposing more ocean, which is darker than ice. So the ocean absorbs more sunlight than before. Very simply, this and other effects are warming the Arctic particularly more than other regions-about 5 degrees Centigrade in the last 30 years.
This means the Arctic is particularly vulnerable. The Antarctic is thick ice mostly on land, so melting does not expose as much of the darker ocean as in the Arctic. The whole subject is complicated, but the conclusion is not: the Arctic seems the best place to use advanced methods of restoring the climate, to that we had only decades ago.
If we understand climate well enough to predict that global warming will be a problem, then plausibly we also understand it well enough to address the problem by direct means. But the central issue is that we do not have time to waste.
Many predict that we will see more severe warming effects, in the Arctic and globally, within a few decades. Ocean acidification takes longer, suggesting a simple priority:
· begin with regional, reversible experiments to define the science · learn from these how well we understand our climate · look for cooling effects · stop the warming to buy time · deal with ocean acidification separately · focus on what we can do now, not what we can do eventually.
We do not have "eventually" - nature works at its own pace.
A Particulate Shield Experiment
But how to begin?
Perhaps the simplest idea uses the suspension of tiny (less than one micron), harmless particles at such altitudes that they will rain out within, say, 6 months. These will reflect mostly ultraviolet, which has a lesser role in plant growth than the lower frequencies, yet carry more energy, which heats when absorbed.
This describes a scientific experiment, designed to understand the complex climate system, not the beginning of an engineering project.
A first test could be over the Arctic, since the warming there is considerable. There the atmospheric circulation patterns tend to confine the deployed particles, sweeping them around the pole but not far southward. The general method seems clear: * Deploy the particles by airplane in the Spring. * Measure the cooling below, using local sensors and space monitoring of the sea ice. * Detect if the present retreat of sea ice toward the north pole slows or even reverses. This will be a clear, visual signature than the region is cooling. Ground measurements will give more refined understanding. The particles can rain or snow out in Fall, ending the experiment in predictable fashion.
One could use just enough of the tiny particles to create a readily measurable shielding effect. An initial experiment could occur north of 70 degrees latitude, over the Arctic Sea and outside national boundaries. The particles would reflect mostly UV rays back into space. They would reduce warming and stop the harm of UV rays to plants and animals, as a side effect. Robust photosynthesis would still occur in the tundra, fueled by the visible spectrum.
This idea exploits our expanding understanding of the climate system. It also uses our historical knowledge of the marked cooling driven by volcanoes in the last several centuries, from sulfate aerosols at high altitude. But sulfates interact chemically with the high altitude air. We can avoid that by using less chemically reactive particles, such as diatomaceous earth. Our aim should be to edit the incoming sunlight, not to interfere with our atmosphere's chemistry.
We can regard these ideas, and the scientific knowledge we gain from such experiments, as tools in a possible future technology. There could be many useful variables in such a climate technology, including particle size, particle nature, altitude deployed (and therefore duration in the atmosphere), and much else. We very probably do not even know all the major influences we will find.
If such an Arctic experiment works, it could tell us much about how to possibly arrest Arctic warming and reverse the loss of sea ice. Since few live people there, any side effects could be minimal. By placing the particles at a high altitude, we can arrange for the first experiments to end when they rain out into the sea, after the main heating during Arctic summer has passed.
Repeating this over several years, to advance our understanding of how our vastly complex climate works, would advance the science. Public discussion could run in parallel, giving the sense that this momentous issue is being freely aired.
This idea is only the first step in making climate science, which has always been passive, into an active science. Astronomy was like this, until the space program began to give us the power to explore the planets, a half century ago. We now do experiments on the soil of Mars, the atmosphere of Jupiter and Venus. With direct measurement comes a new era in any science. All of particle physics has a similar history.
This is not a new transition in science, but it is unique: we live inside the experiment. We have far more at stake.
Diagnosing global climate change is only the beginning. Restoring the stable climate we are now losing is the true, long range goal. But the science comes first.
Saving the Arctic can be the first, trail step. If we find that the pace of forced global climate change is unacceptably high, we could then put this idea to work globally, with all deliberate speed. There could be other side effects on the vastly larger globel scale, and we would have to monitor the entire process very carefully. Some effects could be positive. Lessening UV would lower the human death rate from skin cancer, now about a million per year. Crops under less UV grow better, yielding more food, especially in the tropics.
The main thrust of all this is to carefully use our ability to attack warming at its roots-incoming sunlight now, carbon dioxide later.
The climate system has great inertia and stirs slowly, but once altered, has a momentum of its own. It will be a good idea to have methods like these on the shelf, to deploy quickly. Methods studied this way would be ready for use if the global environment worsens. Given signals that the scarier scenarios of a warming climate might be soon upon us, we could act soon. Such preparations can also establish the political ground for widespread action. Humanity needs to get used to the idea of acting in this wholly new fashion, assuming our role as true stewards of the Earth. Given the magnitude of the possible threat to all societies, such preparations are merely prudent, not radical.
Costs seem readily attainable-perhaps a few hundreds of millions of dollars for an Arctic experiment. High altitude trials over the open ocean are little constrained by law or treaty, so show-stopper politics may be avoided. The first stages will be scientific experiments, not vast engineering projects.
We hope that a favorable experiment could change the terms of the global warming debate for the better. As economist Robert Samuelson recently said, "The trouble with the global warming debate is that it has become a moral crusade when it's really an engineering problem. The inconvenient truth is that if we don't solve the engineering problem, we're helpless."
Before attempting anything like this, detailed theoretical studies are needed, including climate modeling. Even before doing these, however, I can think of a few concerns:
1. Diatomaceous earth is not that safe. From the Wikipedia:
Safety considerations
The absorbent qualities of diatomite can result in a significant drying of the hands, if handled without gloves. The saltwater (industrial) form contains a highly crystalline form of silica, resulting in sharp edges. The sharpness of this version of the material makes it dangerous to breathe and a dust mask is recommended when working with it.
The type of hazard posed by inhalation depends on the form of the silica. Crystalline silica poses a serious inhalation hazard because it can cause silicosis. Amorphous silica can cause dusty lungs, but does not carry the same degree of risk as crystalline silica. Food-grade diatomite generally contains very low percentages of crystalline silica. Diatomite produced for pool filters is treated with heat, causing the formerly amorphous silicon dioxide to assume its crystalline form.
In the United States, the crystalline silica content in the dusts is regulated by the Occupational Safety and Health Administration (OSHA), and there are guidelines for the maximum amounts allowable in the product and in the air near the breathing zone of workers.
2. There is not enough energy in the UV to produce the climate response you want.
3. How can you engineer the particles to only scatter UV and not longer wavelengths?
4. How do you know that reducing UV will be good for the biosphere?
5. When the particles land on sea ice, won't they increase the albedo and cause further melting.
6. Polar amplification of climate response is not as simple as a sea ice/albedo feedback. In fact, if you read my paper on this from 20 years ago, and all the work done since, it is much more complex.
Robock, Alan, 1983: Ice and snow feedbacks and the latitudinal and seasonal distribution of climate sensitivity. J. Atmos. Sci., 40, 986-997.
7. Many of my other concerns about any such experiments remain. But I think climate modeling would be a good start to discover how practical such pollution might be in actually changing the climate.
8. I again note that any perception of success will actually make the ocean acidification problem worse, as it will delay mitigation.
Alan
Alan Robock, Professor II Department of Environmental Sciences Phone: +1-732-932-9478 Rutgers University Fax: +1-732-932-8644 14 College Farm Road E-mail: rob...@envsci.rutgers.edu New Brunswick, NJ 08901-8551 USA http://envsci.rutgers.edu/~robock
On Mon, December 4, 2006 7:04 pm, Gregory Benford wrote:
> A STEP TOWARD SAVING OUR ARCTIC
> GREGORY BENFORD > Department of Physics & Astronomy > University of California, Irvine
> Our biosphere and geosphere do not respond on the time scales of our > institutions. Climate change makes this clear. Humanity has never > confronted a problem of this kind or magnitude before, and we cannot > know how long it will take us to respond to the two major threats we > can now see: > · increasing climate change, driven at a high rate by global warming. > · the rise in acid levels in our ocean, already well documented
> There certainly will be further threats, as our numbers and influences > grow. But at this early stage, in an era that will probably last > centuries, we cannot know them all. We do not understand our world well > enough. But we cannot simply delay.
> We should accept the possibility that anthropogenic carbon emissions > could trigger a climactic tripping point, such as interruption of the > Gulf Stream in the Atlantic. To avoid this, current thinking urges an > all-out effort to shrink the human atmospheric-carbon footprint. But > many energy authorities believe this task will take a century or more. > Our fossil fuel burning is accelerating, not declining.
> So we should also consider relatively low tech, low expense > experiments, to accelerate our understanding of climate science. These > could lead to restoring the climate we prefer. This means changing the > climate on purpose instead of by mistake, as we are doing now. Smart > changes could return us to our earlier, milder world.
> Focusing First on the Arctic
> The two clear threats above develop over different time scales. Very > roughly, ocean acidification is growing over times like fifty years, as > presently observed. The oceans circulate well, so the effects spread > around the globe quite evenly.
> We think of global warming as an effect in our atmosphere, since carbon > dioxide builds up there. But the atmospheric warming also heats the > oceans. This warming is not uniform, though, for many complex reasons. > Sunlight falls most weakly in the Arctic and Antarctic, yet these areas > show the greatest rate of change due to air and ocean warming.
> In the Arctic particularly, the warmer ocean melts ice, exposing more > ocean, which is darker than ice. So the ocean absorbs more sunlight > than before. Very simply, this and other effects are warming the Arctic > particularly more than other regions-about 5 degrees Centigrade in > the last 30 years.
> This means the Arctic is particularly vulnerable. The Antarctic is > thick ice mostly on land, so melting does not expose as much of the > darker ocean as in the Arctic. The whole subject is complicated, but > the conclusion is not: the Arctic seems the best place to use advanced > methods of restoring the climate, to that we had only decades ago.
> If we understand climate well enough to predict that global warming > will be a problem, then plausibly we also understand it well enough to > address the problem by direct means. But the central issue is that we > do not have time to waste.
> Many predict that we will see more severe warming effects, in the > Arctic and globally, within a few decades. Ocean acidification takes > longer, suggesting a simple priority:
> · begin with regional, reversible experiments to define the science > · learn from these how well we understand our climate > · look for cooling effects > · stop the warming to buy time > · deal with ocean acidification separately > · focus on what we can do now, not what we can do eventually.
> We do not have "eventually" - nature works at its own pace.
> A Particulate Shield Experiment
> But how to begin?
> Perhaps the simplest idea uses the suspension of tiny (less than one > micron), harmless particles at such altitudes that they will rain out > within, say, 6 months. These will reflect mostly ultraviolet, which has > a lesser role in plant growth than the lower frequencies, yet carry > more energy, which heats when absorbed.
> This describes a scientific experiment, designed to understand the > complex climate system, not the beginning of an engineering project.
> A first test could be over the Arctic, since the warming there is > considerable. There the atmospheric circulation patterns tend to > confine the deployed particles, sweeping them around the pole but not > far southward. The general method seems clear: > * Deploy the particles by airplane in the Spring. > * Measure the cooling below, using local sensors and space monitoring > of the sea ice. > * Detect if the present retreat of sea ice toward the north pole slows > or even reverses. This will be a clear, visual signature than the > region is cooling. > Ground measurements will give more refined understanding. The > particles can rain or snow out in Fall, ending the experiment in > predictable fashion.
> One could use just enough of the tiny particles to create a readily > measurable shielding effect. An initial experiment could occur north of > 70 degrees latitude, over the Arctic Sea and outside national > boundaries. The particles would reflect mostly UV rays back into space. > They would reduce warming and stop the harm of UV rays to plants and > animals, as a side effect. Robust photosynthesis would still occur in > the tundra, fueled by the visible spectrum.
> This idea exploits our expanding understanding of the climate system. > It also uses our historical knowledge of the marked cooling driven by > volcanoes in the last several centuries, from sulfate aerosols at high > altitude. But sulfates interact chemically with the high altitude air. > We can avoid that by using less chemically reactive particles, such as > diatomaceous earth. Our aim should be to edit the incoming sunlight, > not to interfere with our atmosphere's chemistry.
> We can regard these ideas, and the scientific knowledge we gain from > such experiments, as tools in a possible future technology. There could > be many useful variables in such a climate technology, including > particle size, particle nature, altitude deployed (and therefore > duration in the atmosphere), and much else. We very probably do not > even know all the major influences we will find.
> If such an Arctic experiment works, it could tell us much about how to > possibly arrest Arctic warming and reverse the loss of sea ice. Since > few live people there, any side effects could be minimal. By placing > the particles at a high altitude, we can arrange for the first > experiments to end when they rain out into the sea, after the main > heating during Arctic summer has passed.
> Repeating this over several years, to advance our understanding of how > our vastly complex climate works, would advance the science. Public > discussion could run in parallel, giving the sense that this momentous > issue is being freely aired.
> This idea is only the first step in making climate science, which has > always been passive, into an active science. Astronomy was like this, > until the space program began to give us the power to explore the
Just note that diatomaceous earth hardly seems to have clear dangers ... if it is deployed ... from what we now know. (I hardly need to tell this audience that it is quite necessary to begin to evaluate dangers, not just to enumerate worries. Worries that come up with the course that our society has embarked on seem to be greater and quantifiable.)
As with all particle proposals, it is necessary to consider diatoms throughout a life cycle until removed by lower tropospheric precipitation. Most of the time spent will be in the stratosphere (approx. 6 months minimum to two years or more). Let us posit that it is possible to disperse the diatoms individually at first (how to do that is not obvious); each is then at the smaller end of the submicron accumulation mode. The diatoms should then be condensation sites for sulfate and nitrate, but primarily this will happen only when temperatures and sulfate/nitrate concentrations reach saturation vapor pressure. Most of this has been studied, e.g., by Tilmes or Drdla in a long line of research about condensibles in the stratosphere that may lead to ozone-hole chemistry.
It would still seem likely that the diatoms would have minute (perhaps monolayer) coatings of condensibles like sulfate and nitrate and might also aggregate with other stratospheric trace particles. Since coagulation of particles by normal processes is small at these size ranges, it may occur only when aided by transient "ice" formation in the lowermost stratosphere or uppermost troposphere. Such sulfate or nitrate would not be thermodynamically identical to sulfate or nitrate particles, but the _surface_ _area_ of material exposed to stratospheric chlorine-containing reservoir species would be quite high compared to bulk particles, and would be present at higher temperatures.
Concentrations in the removal region in the troposphere should be minute: the air is diluted tenfold to get to surface pressure, and the removal timescale is probably at least hundred-fold faster compared to stratospheric conditions. An arctic only dispersal region probably implies a lower-tropospheric footprint of depostion at least 5-10 times larger: Near-surface respirable concentrations reduced by at least a factor of ~5000; current trace species analogs could be studied to quantify this. Near-surface aerosols would likely have other components mixed in also: e.g. ammonia and calcium carbonate.
This leads me to two tentative conclusions:
(1) The form of the particle does not appear particularly health-affecting compared to other particles currently in the atmosphere in ultratrace quantities, and probably also similarly coated: soot, lead and heavy metals. (Is there a volcanic-micro-ash parallel, with micron/submicron volcanic silcate particles? I don't know.)
(2) Effects on ozone depletion still require study: effectiveness of the aerosol to shield sunlight implies concentrations approaching volcanic (1/4 Pinatubo or so?) concentrations. There could well be enough area of acid-thin-layer coated diatoms so as to promote "ozone-hole chemistry" ... precisely the heterogeneous conversion of chlorine reservoirs to active chlorine. Conceivably this removes the temperature impediment to heterogenous chemistry described by Tilmes, Tabazadeh, Drdla, and others. This could be very bad. But the effect is hardly certain.
All these uncertainties! Have we gotten anywhere? I believe so. Caution is appropriate, but (potentially) reassuring studies are easy to specify.
Finally: How does this uncertainty compare with the uncertainty in the breakdown speed of the Greenland ice sheet, since we currently lack a mechanistic description of that breakdown, and have competing unquantified theories to explain the accelerated breakdown that we already see? Substantial breakdown on some undetermined timescale is our currently intended program of climatic engineering from which no one can escape responsibility.
My answer to that rhetorical question, ... the diatom consequences are just not that uncertain, and could well be studied. (We always need to stress: action to reduce radiatively active species is always better and should always have the greatest share of our resources.)
Bob Chatfield currently employed as a scientist at NASA Ames Research Center chatfi...@alumni.rice.edu
just a headsup that we're doing a Web forum thru thursday on our yearlong Energy Challenge series, which included Bill Broad's piece on geoengineering gaining 'mainstream' support (cicerone et al).
feel free to weigh in with a posting. could use a bit more 'informed' input to go with some of the old-fashioned deniers who've posted. http://questions.blogs.nytimes.com/2006/12/25/a-reader-forum-on-energ... (you can also send in comments in response to other comments by indicating post # that you're responding to), .
>A STEP TOWARD SAVING OUR ARCTIC >GREGORY BENFORD >Department of Physics & Astronomy >University of California, Irvine >Our biosphere and geosphere do not respond on the time scales of our >institutions. Climate change makes this clear. Humanity has never >confronted a problem of this kind or magnitude before, and we cannot >know how long it will take us to respond to the two major threats we >can now see: >· increasing climate change, driven at a high rate by global warming. >· the rise in acid levels in our ocean, already well documented >There certainly will be further threats, as our numbers and influences >grow. But at this early stage, in an era that will probably last >centuries, we cannot know them all. We do not understand our world well >enough. But we cannot simply delay. >We should accept the possibility that anthropogenic carbon emissions >could trigger a climactic tripping point, such as interruption of the >Gulf Stream in the Atlantic. To avoid this, current thinking urges an >all-out effort to shrink the human atmospheric-carbon footprint. But >many energy authorities believe this task will take a century or more. >Our fossil fuel burning is accelerating, not declining. >So we should also consider relatively low tech, low expense >experiments, to accelerate our understanding of climate science. These >could lead to restoring the climate we prefer. This means changing the >climate on purpose instead of by mistake, as we are doing now. Smart >changes could return us to our earlier, milder world. >Focusing First on the Arctic >The two clear threats above develop over different time scales. Very >roughly, ocean acidification is growing over times like fifty years, as >presently observed. The oceans circulate well, so the effects spread >around the globe quite evenly. >We think of global warming as an effect in our atmosphere, since carbon >dioxide builds up there. But the atmospheric warming also heats the >oceans. This warming is not uniform, though, for many complex reasons. >Sunlight falls most weakly in the Arctic and Antarctic, yet these areas >show the greatest rate of change due to air and ocean warming. >In the Arctic particularly, the warmer ocean melts ice, exposing more >ocean, which is darker than ice. So the ocean absorbs more sunlight >than before. Very simply, this and other effects are warming the Arctic >particularly more than other regions-about 5 degrees Centigrade in >the last 30 years. >This means the Arctic is particularly vulnerable. The Antarctic is >thick ice mostly on land, so melting does not expose as much of the >darker ocean as in the Arctic. The whole subject is complicated, but >the conclusion is not: the Arctic seems the best place to use advanced >methods of restoring the climate, to that we had only decades ago. >If we understand climate well enough to predict that global warming >will be a problem, then plausibly we also understand it well enough to >address the problem by direct means. But the central issue is that we >do not have time to waste. >Many predict that we will see more severe warming effects, in the >Arctic and globally, within a few decades. Ocean acidification takes >longer, suggesting a simple priority: >· begin with regional, reversible experiments to define the science >· learn from these how well we understand our climate >· look for cooling effects >· stop the warming to buy time >· deal with ocean acidification separately >· focus on what we can do now, not what we can do eventually. >We do not have "eventually" - nature works at its own pace. >A Particulate Shield Experiment >But how to begin? >Perhaps the simplest idea uses the suspension of tiny (less than one >micron), harmless particles at such altitudes that they will rain out >within, say, 6 months. These will reflect mostly ultraviolet, which has >a lesser role in plant growth than the lower frequencies, yet carry >more energy, which heats when absorbed. >This describes a scientific experiment, designed to understand the >complex climate system, not the beginning of an engineering project. >A first test could be over the Arctic, since the warming there is >considerable. There the atmospheric circulation patterns tend to >confine the deployed particles, sweeping them around the pole but not >far southward. The general method seems clear: > * Deploy the particles by airplane in the Spring. > * Measure the cooling below, using local sensors and space monitoring >of the sea ice. > * Detect if the present retreat of sea > ice toward the north pole slows >or even reverses. This will be a clear, visual signature than the >region is cooling. > Ground measurements will give more refined understanding. The >particles can rain or snow out in Fall, ending the experiment in >predictable fashion. >One could use just enough of the tiny particles to create a readily >measurable shielding effect. An initial experiment could occur north of >70 degrees latitude, over the Arctic Sea and outside national >boundaries. The particles would reflect mostly UV rays back into space. >They would reduce warming and stop the harm of UV rays to plants and >animals, as a side effect. Robust photosynthesis would still occur in >the tundra, fueled by the visible spectrum. >This idea exploits our expanding understanding of the climate system. >It also uses our historical knowledge of the marked cooling driven by >volcanoes in the last several centuries, from sulfate aerosols at high >altitude. But sulfates interact chemically with the high altitude air. >We can avoid that by using less chemically reactive particles, such as >diatomaceous earth. Our aim should be to edit the incoming sunlight, >not to interfere with our atmosphere's chemistry. >We can regard these ideas, and the scientific knowledge we gain from >such experiments, as tools in a possible future technology. There could >be many useful variables in such a climate technology, including >particle size, particle nature, altitude deployed (and therefore >duration in the atmosphere), and much else. We very probably do not >even know all the major influences we will find. >If such an Arctic experiment works, it could tell us much about how to >possibly arrest Arctic warming and reverse the loss of sea ice. Since >few live people there, any side effects could be minimal. By placing >the particles at a high altitude, we can arrange for the first >experiments to end when they rain out into the sea, after the main >heating during Arctic summer has passed. >Repeating this over several years, to advance our understanding of how >our vastly complex climate works, would advance the science. Public >discussion could run in parallel, giving the sense that this momentous >issue is being freely aired. >This idea is only the first step in making climate science, which has >always been passive, into an active science. Astronomy was like this, >until the space program began to give us the power to explore the >planets, a half century ago. We now do experiments on the soil of Mars, >the atmosphere of Jupiter and Venus. With direct measurement comes a >new era in any science. All of particle physics has a similar history. >This is not a new transition in science, but it is unique: we live >inside the experiment. We have far more at stake. >Diagnosing global climate change is only the beginning. Restoring the >stable climate we are now losing is the true, long range goal. But the >science comes first. >Saving the Arctic can be the first, trail step. If we find that the >pace of forced global climate change is unacceptably high, we could >then put this idea to work globally, with all deliberate speed. There >could be other side effects on the vastly larger globel scale, and we >would have to monitor the entire process very carefully. Some effects >could be positive. Lessening UV would lower the human death rate from >skin cancer, now about a million per year. Crops under less UV grow >better, yielding more food, especially in the tropics. >The main thrust of all this is to carefully use our ability to attack >warming at its roots-incoming sunlight now, carbon dioxide later. >The climate system has great inertia and stirs slowly, but once >altered, has a momentum of its own. It will be a good idea to have >methods like these on the shelf, to deploy quickly. Methods studied >this way would be ready for use if the global environment worsens. >Given signals that the scarier scenarios of a warming climate might be >soon upon us, we could act soon. Such preparations can also establish >the political ground for widespread action. Humanity needs to get used >to the idea of acting in this wholly new fashion, assuming our role as >true stewards of the Earth. Given the magnitude of the possible threat >to all societies, such preparations are merely prudent, not radical. >Costs seem readily attainable-perhaps a few hundreds of millions of >dollars for an Arctic experiment. High altitude trials over the open >ocean are little constrained by law or treaty, so show-stopper politics >may be avoided. The first stages will be scientific experiments, not >vast engineering projects. >We hope that a favorable experiment could change the terms of the >global warming debate for the better. As economist Robert Samuelson >recently
