From sunshades to man-made sulphur-shooting volcanoes, schemes to save the planet are under a microscope
Seth Borenstein
Sun
WASHINGTON — Crazy-sounding ideas for saving the planet are getting a serious look from top scientists.
There’s the man-made volcano that shoots sulphur high into the air. The “sun shade” made of trillions of little reflectors placed in space between Earth and the sun, slightly lowering the planet’s temperature. The forest of ugly artificial “trees” that suck carbon dioxide out of the air. And the “Geritol solution” in which iron dust is dumped into the ocean.
“Of course it’s desperation,” said Stanford University professor Stephen Schneider. “It’s planetary methadone for our planetary heroin addiction. It does come out of the pessimism of any realist that says this planet can’t be trusted to do the right thing.”
NASA has mapped out rough details of the sun shade concept. One of the premier climate modelling centres in the United States, the National Center for Atmospheric Research, has spent run computer simulations of the man-made volcano scenario and will soon turn its attention to the space umbrella idea.
Last month, billionaire Richard Branson offered a $25-million prize to the first feasible technology to reduce carbon dioxide levels in the air.
The proposals, which represent a field called geoengineering, have been characterized as anywhere from “great” to “idiotic,” says one NASA researcher.
These approaches are not an alternative to cutting pollution, said University of Calgary professor David Keith, a top geoengineering researcher. Some scientists have worried that such schemes might distract attention from reducing greenhouse gas emissions.
Here is a look at some of the ideas:
THE GERITOL SOLUTION
Planktos Inc. of Foster City, Calif., last week launched its ship, the Weatherbird II, on a trip to the Pacific Ocean to dump 50 tons of iron dust. The iron should grow plankton, part of an algae bloom that will drink up carbon dioxide from the atmosphere.
The idea of seeding the ocean with iron to beef up a natural plankton and algae system has been tried on a smaller scale several times since 1990. It has both succeeded and failed.
Small experiments “showed unequivocally that there was a biological response to the addition of the iron,” said an international climate report released in 2001. Plankton uses the iron to photosynthesize, extract greenhouse gases from the air, and grow rapidly. It forms a thick green soup of all sorts of carbon dioxide-sucking algae, which sea life feast on, and the carbon drops into the ocean.
However, the climate report also cautioned there could be ecological consequences. For example, large-scale ocean seeding could change the crucial temperature difference between the sea surface and deeper waters and have a dramatic effect on marine life globally.
Russ George, CEO of Planktos, doesn’t want his plan lumped in with geoengineering. He says his company is just trying to restore the ocean to “a more ecologically normal and balanced state.”
“We’re a green solution,” George said.
Planktos officials say that for every ton of iron used, 100,000 tons of carbon will be pulled into the ocean. Eventually, if this first large-scale test works, George hopes to remove three billion tons of carbon from the Earth’s atmosphere.
Planktos’ efforts are financed by companies and individuals who buy carbon credits to offset their use of fossil fuels.
MAN-MADE VOLCANO
When Mount Pinatubo erupted 16 years ago in the Philippines it cooled the Earth for about a year because the sulphate particles in the upper atmosphere reflected some sunlight.
Several leading scientists have proposed doing the same artificially to offset global warming.
Using jet engines, cannons or balloons to get sulphates in the air, humans could reduce the solar heat, and only increase current sulphur pollution by a small percentage, said Tom Wigley of the National Center for Atmospheric Research.
“It’s an issue of the lesser of two evils,” he said.
The results of an NCAR climate model using this method — which involves injecting tens of thousands of tons of sulphate into the atmosphere each month — weren’t cheap or promising.
“From a practical point of view, it’s completely ridiculous,” said NCAR scientist Caspar Amman. “Instead of investing so much into this, it would be much easier to cut down on the initial problem.”
Both this technique and the solar umbrella would reduce heating but wouldn’t reduce carbon dioxide. So they wouldn’t counter a side effect of global warming, a dramatic increase in the acidity of the world’s oceans, which harms sea life, especially coral reefs.
Despite that, Calgary’s David Keith is working on tweaking the concept. He wants to find a more efficient chemical to inject into the atmosphere in case of emergency.
SOLAR UMBRELLA
Last fall, University of Arizona astronomer Roger Angel proposed what he called a “sun shade.” It would be a cloud of small Frisbee-like spaceships that go between Earth and the sun and act as an umbrella, reducing heat from the sun.
“It really is just like turning down the knob by two per cent of what’s coming from the sun,” he said.
The nearly flat discs would each weigh less than 30 grams and measure about a metre wide with three tab-like “ears” — controllers sticking out just a few centimetres. Rockets would be used to deploy them in space.
About 800,000 of the discs would be stacked into each rocket launch. It would take 16 trillion of them — that’s 16 million million — so there would be 20 million launches of rockets.
It would cost at least $4 trillion over 30 years.
“I compare it with sending men to Mars. I think they’re both projects on the same scale,” Angel said. “Given the danger to Earth, I think this project might warrant some fraction of the consideration of sending people to Mars.”
ARTIFICIAL TREES
Scientifically, it’s known as “air capture.” But the instruments being used have been dubbed “artificial trees” — even though these devices are about as tree like as a radiator on a stick. They are designed to mimic the role of trees in using carbon dioxide, but early renderings show them looking more like the creation of a tinkering engineer with lots of steel.
Nearly a decade ago, Columbia University professor Klaus Lackner, hit on an idea for his then-middle school daughter’s science fair project: Create air filters that grab carbon dioxide from the air using chemical absorbers and then compress the carbon dioxide into a liquid or compressed gas that can be shipped elsewhere. When his daughter was able to do it on a tiny scale, Lackner decided to look at doing it globally.
Newly inspired by the $25 million prize offered by Richard Branson, Lackner wants to develop a large filter that would absorb carbon dioxide from the air.
Another chemical reaction would take the carbon from the absorbent material, and then a third process would change that greenhouse gas into a form that could be disposed of.
It would take wind and a lot of energy to power the air capture devices.
They would reach about 60 metres high with various-sized square filters at the top. Lackner envisions perhaps placing 100,000 of them near wind energy turbines.
A filter the size of a television could remove about 25 tons of carbon dioxide a year, which is about how much one American produces annually, Lackner said. The captured carbon dioxide would be changed into a liquid or gas that can be piped away from the air capture devices.
Disposal might be the biggest cost, Lackner said.
Disposal of carbon dioxide, including that from fossil fuel plant emissions, is a major issue of scientific and technological research called sequestration. The idea is to bury it underground, often in old oil wells or deep below the sea floor. The U.S. government, which doesn’t like many geoengineering ideas, is spending hundreds of millions of dollars on carbon sequestration, but mostly for power plant emissions.
© The Vancouver Sun 2007
