Geoengineering Our Way Out of Global Warming

* Nice Weekend? Full Forecast | Cherry Blossom Coverage *

An increasing number of prominent climate scientists and environmentalists (e.g., here and here) are expressing concerns that the point of no return -- when even the most extreme measures to reduce greenhouse gas emissions will be inadequate to reverse many consequences of global warming -- is rapidly approaching.

Speculation on the exact nature of the consequences ranges from coastal cities being submerged under rising seas, more severe floods and droughts, longer and more extreme heat waves, food and water shortages that spark civil unrest, and the reversal of ocean currents leading (ironically) to an ice age, to name a few. Then there's the ultimate doomsday scenarios -- extinction of the human race, or merely the decline of civilization as we know it.

Some of the speculation is based on the latest peer-reviewed science and assessments by the Intergovernmental Panel on Climate Change. The more dramatic end-of-the-world predictions smell more of scaremongering to force policymakers to act, and act now, to reduce emissions of carbon dioxide and other greenhouse gases.

Some of those who believe the tipping point is near -- the point beyond which some impacts of climate change, be they catastrophic or less so, are inevitable -- are giving serious consideration to the idea of geoengineering, deliberate actions taken to slow or reverse global warming by either removing carbon dioxide from the atmosphere or by reducing the amount of sunlight reaching Earth. In other words, Plan B.

Keep reading for more on what geoengineering is all about...

The topic of geoengineering has gained enough traction that the U.S. National Academies is hosting a workshop on the subject this summer, and the UK's national academy of science is preparing a report on the feasibility of climate geoengineering. A recent article in the journal Foreign Affairs states that, "As climate change accelerates, policymakers may have to consider 'geoengineering' as an emergency strategy to cool the planet. Engineering the climate strikes most as a bad idea, but it is time to start taking it seriously." And an advisory group to the Defense Advanced Research Projects Agency recently convened a meeting to discuss geoengineering -- not withstanding concerns expressed by some that military involvement might lead to the use of climate geoengineering as a weapon.

Among the approaches being considered to reduce the solar radiation reaching the ground are firing plumes of fine dust or pumping sulfur dioxide into the atmosphere to deflect the sun's rays in a manner that mimics the cooling effects of volcanic eruptions, and deploying large arrays of land-based mirrors and/or launching mirrors into orbit around Earth (e.g., see here).

Among the schemes for removing carbon dioxide from the atmosphere is dumping tons of iron into the ocean. Iron is necessary for algae photosynthesis, a process that sucks carbon dioxide from the air but is relatively rare in the ocean. In principle, the iron would supercharge the growth of algae, which when it dies would sink to the ocean bottom carrying the carbon with it. A recent iron-fertilization experiment off the coast of Argentina indeed produced a massive algae bloom, but it turned out to be a different kind of algae than anticipated, and one that was quickly devoured by tiny shrimp and other sea life, leaving experts scratching their heads on what the experiment's results mean for iron fertilization as a strategy to sequester carbon. Another approach being discussed is creating plantations of fast-growing trees, which absorb carbon dioxide from the air and convert it into wood, then converting the wood into charcoal (by burning it in the absence of oxygen) and burying the charcoal to prevent the carbon from ever returning to the air.

I've written previously of smaller-scale weather (as opposed to climate) modification programs, including China's efforts to avoid rain during the 2008 Olympics and to induce drought-relieving snowfall by seeding clouds with silver iodide. As I indicated in those posts, neither the Chinese nor anyone else has demonstrated that such weather modification programs produce meaningful changes in overall precipitation patterns. For one thing, it's not possible to know for sure what might have occurred in the absence of cloud seeding. Additionally, it's extremely difficult, maybe impossible, to anticipate unintended consequences -- for example, a seeding-induced increase in precipitation in one place could result in less precipitation somewhere else. In such situations, the legalese of responsibility and liability becomes a major concern.

This classic illustration of the law of unintended consequences -- solving one problem but inadvertently creating another -- is likewise a concern when it comes to geoengineering the climate, but on a much larger scale. This includes addressing questions such as which nation or nongovernmental entity should decide whether the potential benefits outweigh the risks, and who is responsible for correcting (if possible) unintended consequences?

Aside: To the best of my knowledge there's been very little coverage of climate geoengineering and its implications in mainstream newspapers and TV news broadcasts. There are obviously many important issues and events to cover these days, but I'm surprised that geoengineering has not been judged more newsworthy given what's currently happening in the field.

See also our previous post highlighting a new documentary on geoengineering.