‘Plan B’ for a Low-Carbon Economy?

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By Bill Chameides from the Great Energy Blog, a blog produced in partnership with National Geographic.

Putting the "geo" in engineering could screw up the "geo" in politics.

'Plan A' Still on the Table

Scientists have warned for decades that our dependence on fossil fuels is the root cause of global warming and to slow the warming we’ll need to wean ourselves off of them and ramp up low-carbon technologies.

Flash forward to 2011. Fossil fuels are still king and the last 10 years have been the warmest on record. If a low-carbon economy is slowly emerging, it's too small and nascent to count on now. What’s to be done? For some, the answer is Plan B.

'Plan B': Geoengineering

Instead of treating the root cause of global warming — emissions of carbon dioxide (CO2) and other greenhouse gases — Plan B aims to treat the symptoms by “engineering” the climate system to offset the emissions-fueled warming.

Those who consider geoengineering a preferable alternative to a low-carbon economy argue costs would be lower and the “cure” less disruptive. Others view it as more of a “fail safe” system — not on par with lowering greenhouse gas emissions but a last resort if emissions reductions fail to avoid catastrophic climate change.

Beware Unintended Consequences

In a classic commercial from the 1970s a daisy-wreathed woman clad in white, furious at being tricked into thinking margarine was butter, unleashes lightning and thunder, proclaiming, “It’s not nice to fool Mother Nature.” Could geoengineering prompt a similarly destructive response? After all, when you start fiddling with a complex system, it’s awfully hard to be sure what’s going to happen.

Yet, never wont to turn away from a challenge, scientists have taken up the mantle and are trying to suss what might happen should humanity resort to engineering our climate. Case in point: the journal Atmospheric Science Letters is now devoting a special section to the topic.

Offset Warming With Stratospheric Sulfur Injections

One scheme, discussed in the five journal papers out so far, is arguably the most viable under discussion. First proposed back in the 1970s, it involves injecting sulfur gas (e.g., sulfur dioxide) into the stratosphere where it will be chemically converted into small sulfate particles or aerosols. These particles will reflect sunlight back to space, cooling the planet and presumably offsetting the warming. Early calculations indicate that implementation would be relatively inexpensive — for several billion dollars a year, some argue, why not just do it?

One reason is the slippery slope to addiction. Once we start offsetting greenhouse warming using sulfate aerosols, we're going to have to keep at it until we rid the atmosphere of excess greenhouse gases. How long is that? Maybe 1,000 years. If greenhouse gas emissions continue to rise (a real possibility, given all our coal and natural gas reserves), we will have to inject ever-larger amounts. And unfortunately, as Ulrike Niemeier et al of the Max Planck Institute for Meteorology report, we will likely face a case of diminishing returns — the more sulfur we inject, the less effective, pound-for-sulfur-pound, the cooling effect.

Then there are the so-called unintended consequences. Reflecting sunlight back to space from the stratosphere changes how much solar energy reaches the Earth’s surface, and that in turn can play all kinds of mischief with the weather. For example, Peter Braesicke of the University of Cambridge and colleagues report that enhanced stratospheric concentrations of sulfate particles may deplete the ozone layer and alter the El Niño-Southern Oscillation, which plays such a huge role in influencing rainfall globally.

Environmental Concern Plus Geopolitical Landmine

And mucking with weather and more specifically with people's water supply is where things get a little sticky from a geopolitical perspective.

The Unilateral Scenario: Nations' going it alone is potentially the most explosive scenario. For example, suppose a few decades from now India finds the melting of the Himalayan glaciers untenable, and tries to prevent further melting by injecting sulfur into the stratosphere. And suppose in the years following, China experiences devastating droughts that it blames (rightly or wrongly) on India’s sulfur injections. It’s not out of the realm of possibility that China could declare India’s geoengineering an act of war. Now imagine what if China were the geoengineer and the United States the country experiencing droughts or (and it could happen) vice versa.

International Regime: Clearly the unilateral approach is a non-starter. If we are to consider geoengineering, we’d better get busy setting up an international regime to determine:

  • How to decide when it's time to start geoengineering,
  • How to decide if our tinkering is working,
  • How to decide if a nation is being harmed by geoengineering and what to do if it is, and
  • What to do if a nation becomes a rogue geoengineer.

No easy answers, but if geoengineering is in our future, we’d better get those geopolitical answers soon.

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