NCPA - National Center for Policy Analysis


January 30, 2008

Geoengineering is the deliberate modification of the Earth's climate.  It is a stopgap measure that ameliorates the problem of global warming without addressing the underlying cause, says Pete Geddes, executive vice president of the Foundation for Research on Economics and the Environment (FREE) and an adjunct scholar for the National Center for Policy Analysis. 

In 1992 the National Academy of Sciences issued a report, "Policy Implications of Greenhouse Warming: Mitigation, Adaptation, and the Science Base."  It suggested three geoengineering options might be worth exploring: reforestation, directly screening out some sunlight and increasing ocean absorption of CO2.


  • Through photosynthesis, trees remove CO2 from the atmosphere; reforestation in the United States already removes as much as 40 percent of U.S. CO2 emissions from the atmosphere, primarily through the regrowth of eastern forests.
  • Thus reforestation (and reduced deforestation) can play an important role in offsetting carbon emission; this is especially true in the tropics, where trees grow three times faster than in temperate zones and each tropical tree removes about 50 pounds of CO2 from the atmosphere each year. 

Atmospheric Sun Screens:

  • Another geoengineering idea is to mimic the natural cooling effects of volcanic eruptions that release massive amounts of sulfur dioxide (SO2) into the atmosphere; SO2 eventually turns into highly reflective solid particles that bounce solar radiation back into space.
  • Gregory Benford has proposed a variation on this idea, Science magazine reports; he suggests increasing the planet's reflectivity by putting tiny particles of silicon dioxide (basically, kitty litter) into the stratosphere.

Ocean Absorption:

  • A third idea is to add iron to the upper layers of the ocean; iron acts as a fertilizer, increasing the growth of phytoplankton which, like all plants, create carbon compounds by removing CO2 from the atmosphere. 
  • The resulting "algal blooms," when they sink, would take carbon to the sea floor, essentially storing it away. 

Source: Pete Geddes, "Geoengineering: A Global Warming Fix?" National Center for Policy Analysis, Brief Analysis No. 607, January 30, 2008.

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