The growing gap between ambitious climate targets and inaction to achieve them is prompting more calls from emissions-tracking specialists for the global community to “get serious” about a controversial topic in climate solutions: climate engineering.
Under 2015’s breakthrough Paris Agreement, nations are committed to keeping global warming under 2C above pre-industrial temperatures, with a further aspirational goal of 1.5C. But the total national emissions mitigation pledges submitted to the United Nations would likely result in 3C of warming, according to the UN Environment Programme.
Most emissions scenarios targeting the 2C guardrail assume a vast application of negative emissions technology, or what is called “carbon dioxide removal” (CDR)—the drawdown of greenhouse gases from the atmosphere. In these scenarios, widespread CDR deployment—often assumed to be provided by bioenergy sources coupled with carbon dioxide capture and storage (BECCS)—is described as starting as early as 2020. By 2100 it is expected to have to be removing the equivalent of as much as half of all current annual emissions.
CDR is just one of two broad categories of what is called “climate engineering,” or more commonly termed geoengineering: actively intervening in the Earth system to maintain optimum average global temperatures. The other type of climate engineering, solar radiation management (SRM), involves spraying a reflective mist of sulphate aerosols into the upper atmosphere to scatter about one percent of the sun’s rays, which in just over a year could cool the Earth about half a degree—and at a cost of just a few billion dollars.
Both types have considerable environmental risks and global governance impacts. At the volumes of BECCS envisaged in the 2C emissions scenarios—equivalent to creating another carbon sink on the scale of the world’s oceans—the land required for such crops would impinge on that required for food production. SRM at a very large scale could disrupt Asian and African monsoon seasons.
In addition, SRM is cheap enough that many countries, particularly those at the sharp end of climate impacts—or even just a very wealthy individual—might be tempted to engage unilaterally, regardless of the impacts in other countries. Whether climate engineering is to be supported or opposed, some form of international governance structure would be necessary.
Glen Peters and Oliver Geden, two researchers focused on the challenge of negative emissions, noted in an August commentary in Nature Climate Change: “Most policymakers, heads of state and governments seem to be unaware of the broader political implications.” They argue that governments need to develop policies to incentivize researchers and businesses to develop negative emissions technologies. States should also begin negotiating amongst each other differentiated responsibilities for such endeavours, they add, as some states will argue that due to their greater historic emissions, it is only fair that some countries go carbon negative before others.
The same month, in a pair of papers, one appearing in the Proceedings of the National Academy of Sciences and the other produced for the Centre for International Governance Innovation, environmental legal scholar Ted Parson argued for the creation of a World Commission on Climate Engineering that would start the process of establishing global governance of the subject. He worries that key figures have failed to speak clearly about the issue due to worries that it may undermine emissions mitigation efforts.
While neither supporting nor opposing climate engineering, Parson says that a global governance framework is necessary even just to establish that this is not a path we wish to go down.
“Neither large-scale carbon removal nor solar geo-engineering would have any role as part of an ideal response to climate change,” Parson continues. “But that ship has sailed.”
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