I wrote a post last month considering the potential importance of geoengineering in future climate policy debates. Since then, a number of new reports have been released—see those of the Royal Society and the Institution of Mechanical Engineers—along with a number of news articles considering the merits of each of their proposals.

New reports suggest India’s CO₂ emissions could quadruple by 2030. This fact, along with other evidence that increasing temperatures have put the brakes on cooling Arctic summers, could bolster the case for geoengineering and help current proposals leap from idea to reality.

While the buzz surrounding geoengineering would suggest a certain level of viability, many of the current proposals lack political and/or economic feasibility. While proposals could become more plausible over time, objective consideration of some of the current geoengineering alternatives reveals a need for continued research and public scrutiny.

A Temporary Fix

Consider one form of a solar radiation management strategy for reducing the effects of greenhouse gas emission accumulation in the atmosphere: painting the world’s rooftops white. Energy Secretary Steven Chu’s said earlier this summer painting the world’s rooftops white would be equivalent to removing every car on Earth from the road for 11 years. And while that suggestion sounds intriguing, the fact of the matter is that this approach and others like “artificial trees” to absorb CO₂ do nothing to remove the actual cause of the problem in the first place.

Failing to address the root cause is perhaps the most pronounced problem of current geoengineering proposals, aside from their economic feasibility. By addressing the symptoms and not the cause, we are simply reducing certain risks while creating others that are not yet well understood. Take the current proposal of using stratospheric aerosols to reduce the effects of greenhouse gas accumulation. While a similar tactic, e.g. cloud seeding, has been used before, the concerns about intentionally influencing the climate system to achieve a particular set of objectives are well founded. The unintended consequences of such actions may not yet be well known and these counteracting effects could be quite dangerous. Moreover, the potential for international externalities that could arise from these unintended consequences likely makes political acceptance for the proposal harder to come by.

Not addressing the root causes also brings up the issue of the long-term viability of any proposal that simply removes CO₂ from the atmosphere. Recently in the Washington Post, senior scientist at the Carnegie Institution, Ken Calderia said he finds geoengineering somewhat worrisome. In his remarks he suggests that without actual mitigation, the long-term viability of any large scale geoengineering proposal is of the upmost importance. Since emissions would continue rising, society would be forced to maintain whichever proposal(s) it had originally adopted indefinitely unless some form of mitigation had already taken place.

Political and Economic Implications

Failure to address root causes aside, it is clear that the economic and political feasibility of any proposal are intricately connected. Consider the case of “artificial trees” discussed in the report released by the Institution of Mechanical Engineers. While they discuss the potential for improvements in the production process, the financial cost incurred to undergo this route seems large.

The current cost of one of these “trees” is close to $20,000. Approximately 10 million trees are needed to collect 3.6 Gt/yr of CO₂ emissions (about 12.5% of world annual emissions). This means the cost of producing enough of these trees to capture half of world emissions is close to $800 billion (4*10 million trees*$20,000/tree is 14.4 Gt/yr in emissions captured). The report further says the production cost represents only about 20% of the total cost of this type of a proposal. The rest of the cost comes from removing CO₂ from the filters. Assuming that each of these trees lasts indefinitely (simply not the case but a premise that provides a lower estimate of total costs), one can easily calculate the upfront cost to be around $4 trillion with annual expenses thereafter of nearly $3 trillion (mainly for the removal of CO2) – a sizeable proportion of world GDP. Granted the authors discuss the possibility that production advantages will lead to cheaper trees and more efficient ones at that. Even if this is the case, when this happens and how close it matches the authors’ beliefs in terms of efficiency gains are unclear.

With these facts in mind it is clear that much work still needs to be done before geoengineering becomes a viable option for addressing the issues that climate change presents. The Royal Society is probably right in proposing that money being allocated to consider the merits of some of the current proposals. There is much to say about having a plan B when it comes to climate but we shouldn’t forget some of the obvious drawbacks.

Eric Moore is a research assistant at Resources for the Future.