Geo-Engineering: Methadone for Carbon Addiction

Lisa Moore's profileWhat if, instead of reducing the greenhouse gas concentrations that hold excess heat in our atmosphere, we injected something in the atmosphere to reflect sunlight back into space? That's the idea behind sulfate geo-engineering. As Bill wrote in his post "Can we engineer our way out?", there are a plethora of problems with geo-engineering, but scientists still study it as an option of last resort.

The idea of injecting sulfates into the atmosphere is based on the observation that large volcanic eruptions can cause short-term global cooling. But in addition to the usual problems with geo-engineering (for example, it does nothing to stop ocean acidification from excess CO2), scientists have found a new one. Sulfate geo-engineering could endanger food and water supplies for billions of people in Africa and Asia, according to a recent paper in the Journal of Geophysical Research [PDF].

A Study with Some Scary Findings

Continuous sulfate injections into the stratosphere might cool the Earth, but does it matter where you do it? And what else might it do? To address these questions, the researchers ran a global climate model under four scenarios:

  1. Business-as-usual with no geo-engineering
  2. Low-level sulfate injections in the Arctic
  3. Medium-level sulfate injections in the tropics
  4. High-level sulfate injections in the tropics

In all the geo-engineering scenarios, sulfate was injected continuously for 20 years, and then abruptly turned off. The medium-level is roughly equivalent to a Pinatubo eruption every four years, the high-level every two years.

Compared to business-as-usual, the geo-engineering strategies slowed or even reversed global warming and the loss of Arctic summer sea ice. So far so good. But scientists found serious drawbacks when they looked at (1) regional effects and (2) the consequences of suddenly ending sulfate injections.

One of the most prominent dangers was the effect on summer monsoons in Africa and Asia, on which billions of people rely for food and water supplies. Both monsoon systems decreased markedly when sulfate was injected into the atmosphere – regardless of how much or where.

And what about when sulfate injections stopped, as might happen if a real-world geo-engineering strategy encountered technical difficulties or lost political support? The resulting warming rebound and sea ice loss was "more rapid … than has occurred in the past century or than is projected with business as usual." Since the rate of warming can be as damaging as temperature alone, warming rebound could have tremendous environmental and social consequences.

Best to Tackle the Root of the Problem

This paper adds to the growing list of geo-engineering risks (for example, see 20 reasons why geoengineering may be a bad idea [PDF]). As RealClimate scientists put it in their coverage of the latest paper, geo-engineering is like methadone: "an emergency treatment to substitute one addiction (carbon emissions) with another." What we really need to do is tackle the root of the problem and decrease greenhouse gas emissions.

This post is by Lisa Moore, Ph.D., a scientist in the Climate and Air program at Environmental Defense Fund.

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3 Comments

  1. Peter Black
    Posted October 8, 2008 at 3:12 pm | Permalink

    Better to think about doing this on Mars in preparation for our colonization of that planet.

  2. kenzrw
    Posted October 8, 2008 at 6:05 pm | Permalink

    Let's hope we don't do anything before making sure it's a safe thing to do (i.e., like the corn biofuel rush before there were sufficient standards to prevent deforestation to plant crops, etc., which resulted in corn-based biofuel creating a worse carbon footprint than using gasoline).

    Windmills and solar power are part of the solution. A Danish company has recently announced that it will create 830 jobs in central Arkansas by building a wind turbine facility here. My only question is WHY does it have to be a foreign country manufacturing these? Can't we do any kind of manuracturing with a U.S. based company anymore?

  3. climatewiz
    Posted February 11, 2010 at 8:54 am | Permalink

    I see you removed my previous post. C'mon… a little much needed truth concerning the bloviated touting of bogus "peer review" seems to be needed now…. Consider this:

    "What a man believes upon grossly insufficient evidence is an index into his desires — desires of which he himself is often unconscious. If a man is offered a fact which goes against his instincts, he will scrutinize it closely, and unless the evidence is overwhelming, he will refuse to believe it. If, on the other hand, he is offered something which affords a reason for acting in accordance to his instincts, he will accept it even on the slightest evidence. The origin of myths is explained in this way."
    Bertrand Russell Global warming = myth

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