Not only do two of the most popular ideas put forward for mitigating climate change – so-called “geoengineering” – need substantially more research before they can be considered safe, but doing so instead of reducing carbon dioxide emissions today would be “irrational and irresponsible” on the part of the public and policymakers.
That’s the summary of a major investigation by the US National Research Council, published this week in the hopes of informing “the technological, ethical, legal, economic and political discussions that surround the topic of climate intervention”. The two proposals studied – removing carbon dioxide from the atmosphere, or blocking heat from the sun – are seen as unrealistic and overambitious, relative to our current technological abilities.
Human intervention is the major contributing factor in the changing chemistry of the Earth’s atmosphere. Its fragility and complexity has meant that a small global rise in temperature in the last century (roughly 0.85 degrees) has already had severe ramifications, like depleted polar sea ice, accelerated sea level rise and more intense, more prolonged heat waves. Over the last few years, as greenhouse gas emissions continue to rise and international governments struggle to achieve serious agreement on fixing the problem, some scientists and entrepreneurs have gravitated towards geoengineering as the solution.
To give a sense of how serious climate change is, and how long-lasting the damage will be, it would take a thousand years to get back to the pre-Industrial Revolution “normal” equilibrium if all our carbon dioxide emissions (besides, well, breathing) were to stop today. To avoid the worst effects of global warming, present day gas emissions would have to be reduced by at least 90 per cent, but the political, economical and social issues blocking action may well continue for years to come. The UN Climate Summit at Paris in December 2015 will have 196 countries attempt to agree on a new agreement for a meaningful legal action on climate change, but the chances of a major new deal are slim.
This sense that time is running out has given geoengineering, previously a fringe discipline, a new kind of respectability. Yet, as the NRC reports conclude, that’s not good enough – climate intervention technology is still in its infancy; there are plenty of issues left to be resolved, such as its effectiveness, economic cost and the potential for unintended consequences.
The 400-page report, authored by the 16 members of the NRC’s multidisciplinary Committee on Geoengineering Climate, is split into two volumes: one assesses carbon dioxide removal (CDR), the other solar radiation management (or “albedo modification”).
When it comes to CDR, the report finds that the technology to suck up and trap CO2 from the atmosphere is extremely primitive, and for reasons “largely related to slow implementation, limited capacity, policy considerations, and high costs of presently available technologies” it’s a non-starter for now. This includes methods like iron fertilisation, for example, where iron filings are dumped into oceans, causing massive plankton blooms. When that plankton dies, they take the carbon dioxide with them to the sea floor, where it (hopefully) remains indefinitely. Yet it could cause a knock-on effect by changing the ecology of the oceans, upsetting food chains, suffocating fish and leading to marine species extinctions.
The committee concluded that effective, industrial-scale CDR tech is still many years away, but regardless, “it is increasingly likely that we will need to deploy some form of CDR to avoid the worst impacts of climate change”.
Albedo modification, the other alternative, deals with controlling how much of the Sun’s light and energy is reflected from the Earth back into space by spraying aerosols from planes – either to induce thicker cloud cover, or to make existing clouds whiter and, therefore, more reflective.
The report found that AR “shows some evidence of being effective at temporarily cooling the planet, but at a currently unknown environmental price”. The profound side effects of trying to control the amount of light and heat that reaches the Earth’s surface should not be underestimated – the unforeseen side effects on everything from agricultural yields to extreme weather are currently unknown. “Understanding of the ethical, political, and environmental consequences of an albedo modification action is relatively less advanced than the technical capacity to execute it,” the authors write.
The positives and negatives of two main types of geoengineering proposals. Image: NRC
The Committee concluded that “climate change is a global challenge, and addressing it will require a portfolio of responses with varying degrees of risk and efficacy”. They go on:
There is no substitute for dramatic reductions in greenhouse gas emissions to mitigate the negative consequences of climate change, together with adaptation of human and natural systems to make them more resilient to changing climate. However, if society ultimately decides to intervene in Earth’s climate, the Committee most strongly recommends any such actions be informed by a far more substantive body of scientific research — encompassing climate science and economic, political, ethical, and other dimensions — than is available at present.”
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