Saving the Arctic
Gregory Benford
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."
Alan Robock
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.
http://climate.envsci.rutgers.edu/pdf/RobockIceSnowJAS1983.pdf
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
Bob Chatfield
... 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
chat...@alumni.rice.edu
XBen...@aol.com
Thanks, Bob! Quite clear & useful.
Gregory
Andy Revkin
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-energy-and-the-environment/#respond
(you can also send in comments in response to other comments by indicating post # that you're responding to), .
andy
ANDREW C. REVKIN
The New York Times / Environment
229 West 43d St., NY NY 10036
phone: 212-556-7326 / e-mail: rev...@nytimes.com / fax: 509-357-0965
Arctic book: The North Pole Was Here: www.nytimes.com/learning/globalwarming
Amazon book: The Burning Season www.islandpress.org/burning
Acoustic-roots band: www.myspace.com/unclewade