A biased economic analysis of geoengineering

But Bickel and Lane ignore the effects of ocean acidification from continued CO2 emissions, dismissing this as a lost cause. Even without global warming, reducing CO2 emissions is needed to do the best we can to save the ocean. The costs of this continuing damage to the planet, which geoengineering will do nothing to address, are ignored in the analysis in this report. And without mitigation, SRM would need to be continued for hundreds of years. If it were stopped, by the loss of interest or means by society, the resulting rapid warming would be much more dangerous than the gradual warming we are now experiencing.

Bickel and Lane do not even mention several potential negative effects of SRM, including getting rid of blue skies, huge reductions in solar power from systems using direct solar radiation, or ruining terrestrial optical astronomy. They imply that SRM technologies will work perfectly, and ignore unknown unknowns. Not one cloud has ever been artificially brightened by injection of sea salt aerosols, yet this report claims to be able to quantify the benefits and the costs to society of cloud brightening.

They also imply that stratospheric geoengineering can be tested at a small scale, but this is not true. Small injections of SO2 into the stratosphere would actually produce small radiative forcing, and we would not be able to separate the effects from weather noise. The small volcanic eruptions of the past year (1.5 Tg SO2 from Kasatochi in 2008 and 1 Tg SO2 from Sarychev in 2009, as compared to 7 Tg SO2 from El Chichón in 1982 and 20 Tg SO2 from Pinatubo in 1991) have produced stratospheric clouds that can be well-observed, but we cannot detect any climate impacts. Only a large-scale stratospheric injection could produce measurable impacts. This means that the path they propose would lead directly to geoengineering, even just to test it, and then it would be much harder to stop, what with commercial interests in continuing (e.g., Star Wars, which has not even ever worked).

Bickel and Lane also ignore several seminal papers on geoengineering that present much more advanced scientific results than the older papers they cite. In particular, they ignore Tilmes et al. (2008), Robock et al. (2008), Rasch et al. (2008), and Jones et al. (2009).

With respect to ozone, they dismiss concerns about ozone depletion and enhanced UV by citing Wigley (2006) and Crutzen (2006), but ignore the results of Tilmes et al. (2008), who showed that the effects would prolong the ozone hole for decades and that deployment of stratospheric aerosols in a couple decades would not be safe as claimed here. Bickel and Lane assert, completely incorrectly, “On its face, though, it does not appear that the ozone issue would be likely to invalidate the concept of stratospheric aerosols.”

With respect to an Arctic-only scheme, they suggest in several places that it would be possible to control Arctic climate based on the results of Caldeira and Wood (2008) who artificially reduce sunlight in a polar cap in their model (the “yarmulke method”), whereas Robock et al. (2008) showed with a more realistic model that explicitly treats the distribution and transport of stratospheric aerosols, that the aerosols could not be confined to just the Arctic, and such a deployment strategy would affect the summer Asian monsoon, reducing precipitation over China and India. And Robock et al. (2008) give examples from past volcanic eruptions that illustrate this effect, such as the pattern of precipitation reduction after the 1991 Pinatubo eruption (Trenberth and Dai, 2007):

With respect to cloud brightening, Bickel and Lane ignore the Jones et al. (2009) results that cloud brightening would mainly cool the oceans and not affect land temperature much, so that it is an imperfect method at best to counter global warming. Furthermore Jones et al. (2009) found that cloud brightening over the South Atlantic would produce severe drought over the Amazon, destroying the tropical forest.

They also ignore a huge class of ethical and world governance issues. Whose hand would be on the global thermostat? Who would trust military aircraft or a multi-national geoengineering company to have the interests of the people of the planet foremost?

They do not seem to realize that volcanic eruptions affect climate change because of sulfate aerosols produced from sulfur dioxide gas injections into the stratosphere, the same that is proposed for SRM, and not by larger ash particles that fall out quickly after and eruption and do not cause climate change.

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