Geo-Engineering Seen as a Practical, Cost-Effective Global Warming Strategy

Published December 1, 2007

Geo-engineering the Earth’s atmosphere with reflective aerosols presents the most cost-effective and reliable means of keeping the Earth’s temperature within a desirable range, David Schnare, senior fellow for energy and the environment at the Thomas Jefferson Institute for Public Policy, told the U.S. Senate Committee on Environment and Public Works in September 26 testimony.

In addition to being much less expensive than seeking to stem temperature rise solely through the reduction of greenhouse gas emissions, geo-engineering has the benefit of delivering measurable results in a matter of weeks rather than the decades or centuries required for greenhouse gas reductions to take full effect.

Schnare’s testimony was presented in the context of hearings regarding the plight of the Chesapeake Bay due to projected global warming, but his observations are globally applicable. Reproduced below is a condensed version of Schnare’s testimony.

The greatest threat to restoration of the Chesapeake Bay comes not from the potential geophysical effects of climate change, but from the potential responses to climate change and, in particular, exclusive reliance on a strategy of reducing greenhouse gases. The scientific community has reached a consensus on this. As Nobel Laureate Paul Crutzen admits, efforts to forestall climate change exclusively through reductions in greenhouse gases are no more than “a pious wish.”

Public reports show nations have rejected this strategy, and without full, massive global cooperation, reliance on greenhouse gas reductions alone will fail.

Firm Evidence of Success

In his influential law review article [Stanford Environmental Law Journal, January 1998], New York University Law School Golieb Fellow Jay Michaelson suggests, “We need an alternative to the policy myopia that sees emission reductions as the sole path to climate change abatement,” and in particular we need to apply geo-engineering that can prevent global warming and reduce acidification of the oceans. Others agree.


Alan Carlin, senior economist with the U.S. Environmental Protection Agency, argues that geo-engineering is “our best hope of coping with a changing world.” It is our best hope because we have firm evidence it will work and because the developing world can afford this approach.

As Ken Caldeira, a professor of climate science at Stanford University, explains, reducing greenhouse gases will cost around 2 percent of the gross domestic product, while geo-engineering (by putting reflective aerosols into the upper atmosphere) will cost about one-thousandth of that.

Tremendous Cost Advantages

Indeed, the IPCC and William D. Nordhaus, Sterling Professor of Economics at Yale University, agree the price tag for preventing the effects of global warming with geo-engineering is so small as to be considered virtually “costless.”

More significantly, Professor Scott Barrett, director of the Johns Hopkins University School of Advanced International Studies, argues convincingly that because geo-engineering is the only practical means to mitigate catastrophic climate change, and is a virtually costless means of doing so, use of this technology is inevitable and our task is to ensure we do it in a sensible, incremental, and reasoned manner.

The seven (preventable) irreversible events [affecting global warming] reach their first “tipping point” with melting of the Greenland ice sheet, an event that commences with a 1.2º to 2º C rise in global temperature and which, according to the IPCC(2007) may have already, albeit slowly, begun. We must keep in mind, however, that complete melting of the ice sheet would cause a seven meter ocean rise only after some 300 to 1,000 years. This long melting timescale assumes CO2 rises to nearly three times the current level (four times the pre-industrial level) and stays that high for a millennium.

The other six events do not reach their tipping points until global temperatures increase by about 3º to 6º C.

Techniques Already Known

The first of the two most common examples [of warming mitigation techniques] cited is placement of reflective aerosols into the upper atmosphere in order to reflect incoming sunlight and thus reduce global temperature. The second is injecting iron into parts of the ocean in order to speed the growth of phytoplankton and thus sequester carbon. Similar techniques can be used to inject lime into the ocean and reduce near-coast water acidity, and thereby protect coral reefs and shellfish.

You might think of geo-engineering as a human effort to replicate natural processes such as volcanic eruptions that inject large quantities of sulfates into the air and thereby shield the planet from sunlight. The eruption of Mount Pinatubo in the Philippines in 1991 injected a significant amount of sulfur dioxide into the stratosphere, lowering the Earth’s surface temperature by about 0.5ºC the year following the eruption.

The extremely low cost of geo-engineering allows many like Barrett to describe these techniques as economically “incredible.” [The accompanying table] shows geo-engineering is not merely 200 to 2,000 times less expensive, but it prevents more damage than exclusive reliance on carbon control.

Additional Cancer Benefits

Further, consider a risk not included in the $17 trillion worth of residual global warming damages shown in the table–the $10 billion a year cost to the United States from ultraviolet (UV)-caused cancer that would be avoided using geo-engineering.

In practical terms, the benefits to the United States alone, and for UV-related cancer alone, justify using geo-engineering–a gift to the world that would prevent some $5.2 trillion in [anticipated] global warming-caused damages.

Geo-Engineering Already Occurring

Notably, geo-engineering has gone commercial. Planktos, Inc., for example, is a for-profit ecorestoration company based in San Francisco with offices in the European Union and British Columbia. Its primary focus is to restore damaged habitats in the ocean and on land. The firm injects iron into iron-deficient waters to induce large blooms of plankton. This helps sequester carbon, and Planktos sells carbon sequestration credits on the various carbon markets.

In light of [University of Chicago Law School Distinguished Professor Cass] Sunstein’s admonition [to avoid the twin dangers of overreaction and apathy] and the economic and fiscal realities of global warming, geo-engineering, and alternatives thereto, the most sensible approach would be a mixed strategy of geo-engineering to prevent further global warming and the effects of ocean acidification over the next century or two and vigorously developing a transition from carbon-based energy, to include research on scrubbing greenhouse gases from the atmosphere.

For more information …

“Responses to Climate Change and their Implications on Preservation and Restoration of the Chesapeake Bay,” Testimony Before the United States Senate Committee on Environment and Public Works, Wednesday, September 26, 2007: