The Space Review

sunshade illustration
Building space-based sunshades might be a good way to deal with climate change, if the deal is sweetened with some extraterrestrial property rights. (credit: Univ. of Arizona)

Rock, paper, scissors, lizard, Spock… and global warming policy choice

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The conjuncture of environmental protection, international law, and political economy renders every policy response to global warming imperfect. In an example of Condorcet’s Paradox, any policy response preferred according to one set of values, and perhaps acceptable according to another, is rejected according to yet another. Is the same true for space-based solutions to the issue?

Consider global greenhouse gas emissions reduction via government taxation and regulation. Popular because it carries no risk of additional environmental harm and promises restoration of the climate to an early industrial status quo, and permissible under international law, it runs afoul of the collective action problem in political economy. Realizing this policy is the ostensible goal of the annual Conferences of Parties for the Kyoto Protocol since 1995, but the product of those negotiations has been a record of failure to share the burden. Most states appear determined to free ride on any reductions in emissions made by a handful of more virtuous states.1

A wealthy spacefaring power might still be persuaded to undertake the Herculean task of constructing a sunshade in exchange for something else that it values: the extraterrestrial location where it mines the raw material and manufactures the necessary components.

Next consider cloud whitening, the continual dispersal of sea salt in clouds to enhance albedo. Such a policy would avoid the collective action problem inherent in negotiating a successful comprehensive international agreement because it could be executed either by individual states or small numbers of states interested in realizing a regional rather than a global climate benefit. It would encounter less (but still some2) opposition because of anticipated environmental harm than other geoengineering proposals because it would be both relatively inexpensive and readily reversible.3 The veto is found in international law. Multiple international treaties establish a duty not to cause transboundary harm, reversible or not, to the atmosphere.4

And next consider ocean fertilization, the adding of nutrients for phytoplankton in the oceans to increase carbon sequestration. Surprisingly, this policy may be more acceptable according to international law than the other geoengineering proposals involving the oceans. The 1996 London Protocol was amended in 2006 to permit sub-seabed geological carbon sequestration.5 Ocean fertilization is inhibited by a surmountable political action problem: the absence of any legal basis for including it in schemes for acquiring carbon credits. The likely veto comes from environmental science.

On first inspection, there appears no escape from this policy intransitivity in space. Although deploying a sunshade to deflect solar radiation either in near Earth orbit or at the Earth-Sun L1 point would be permissible under international law, and the possible environmental harm would be markedly less if constructed from materials mined and manufactured in space, considerations of political economy present significant obstacles. The first is moral hazard. An effective sunshade would weaken the impetus for states to curb greenhouse gas emissions. The second is the sort of free riding associated with collective goods. Roger Angel estimates the cost of constructing a smart cloud sunshade at L1 at $5 trillion.6 States making no contribution to the cost of constructing a sunshade could not be excluded from its benefits. Little imagination is needed to anticipate refusals to contribute by the overlapping categories of states that are small, poor, and lack serious space programs. Skipping out on the bill would probably be justified in terms of distributive justice claims that characterize much of the discussion of global warming in international fora.

In the absence of a planetary government with the power to extract contributions from the free riders, a wealthy spacefaring power might still be persuaded to undertake the Herculean task of constructing a sunshade in exchange for something else that it values.7 One possibility is that it might accept the extraterrestrial location where it mines the raw material and manufactures the necessary components as the reward for its efforts. In effect, sovereign territory on the Moon or, at the very least, a monopoly on the remaining mineral resources from a captured asteroid might serve as payment. Note, this assumes that the 1967 Outer Space Treaty will still be the basis for the international space legal regime and that free riders possess some collective ownership that they could sacrifice. That this treaty is actually a rather flimsy barrier to asserting claims of sovereign extraterrestrial territory is clear.8

Maintaining a climate on Earth permitting majority of humanity to live long and prosper would be the chief benefit of constructing a sunshade. Another is that it would necessitate activity in space on a scale that might be open it to development and settlement beyond near Earth orbit. That would increase the value of any extraterrestrial reward given to the spacefaring power that constructs a sunshade.


1 Spock’s comment on diplomacy in the Star Trek episode “The Mark of Gideon” (January 17, 1969) is apt: “We must acknowledge, once and for all, that the purpose of diplomacy is to prolong a crisis.”

2 Alan Robock warns that humanity might suffer psychological harm because of the disappearance of blue skies and the increased frequency of red sunsets. “20 Reasons Why Geoengineering May Be a Bad Idea.” Bulletin of the Atomic Scientists. May/June 2008.

3 The Royal Society. “Geoengineering the Climate: Science, Governance and Uncertainty.” September 1, 2009. p. 28.

4 Ibid., p. 40.

5 Kelsi Bracmort and Richard K. Lattanzio. “Geoengineering: Governance and Technology Policy.” Congressional Research Service. January 2, 2013. p. 33.

6 Roger Angel. “Feasibility of Cooling the Earth With a Cloud of Small Spacecraft Near the Inner Lagrange Point (L1).” PNAS. November 14, 2006.

7 Only in the dream palace of the libertarians would private firms agree to bear such an economic risk.

8 John Hickman. “Red Moon Rising.” Foreign Policy. July/August 2012.



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