Reducing methane emissions will simply not be enough to cap global heating at 1.5°C, said researchers at a COP 26 side event Monday who pleaded for funding and policy support for technologies that actively remove the climate super-pollutant from the atmosphere.
Though rapid methane reductions will buy valuable time, that single-faceted strategy will fall short given the barriers to limiting emissions from the meat and dairy sectors, Lena Höglund-Isaksson, a researcher at the International Institute for Applied Systems Analysis, told a session hosted by the non-profit Methane Action,
Enter methane removal technologies, which Stanford University Earth System scientist Rob Jackson presented as an effort in keeping with the United Nations Ecosystem Restoration 2021-2030 initiative.
He introduced five promising technologies, before turning to one in particular, the creation of iron-salt aerosols (ISAs).
Based on the finding that the chlorine in sea spray draws down (oxidizes) anywhere between 2 and 20% of atmospheric methane, researchers like Jackson and Methane Action Science Advisor Maarten van Herpen are pursuing the idea that human-made iron-salts could do the same, only to a much greater degree.
In an observation that rang some climate alarm bells in the audience, University of Copenhagen chemistry professor Matthew Johnson suggested the world’s marine vessels, which emit iron in their (fossil fuel) exhaust, might somehow be harnessed to help seed these ISAs in the atmosphere. Johnson claimed his team’s method would improve air quality and help restore atmospheric methane to pre-industrial levels.
It was unclear during the session to what extent the technology would depend upon the world’s highly polluting marine fleet. Johnson was also sanguine on the question of how adding iron to the atmosphere might affect marine ecosystems, asserting several times that the amounts in question would be far less than what is delivered into the oceans by natural means every year.
Methane Action CEO Daphne Wysham said her organization is “agnostic” about the technologies under consideration, and committed to a full environmental assessment of the impacts of any technology, to be conducted by an independent third party.
Renaud de Richter of Montpellier University’s National Engineering School of Chemistry discussed the promise of “solar chimneys,” explaining that their core value (both as a source of renewable power and as a means to draw down methane) is that they move huge amounts of air passively. Researchers have projected that one 400-megawatt chimney (still at the design concept stage) could move 38,000 cubic kilometres of air per year. Add photocatalysts to the chimney surface, said de Richter, and sunlight will transform methane (and CO2) to “lower carbon gases.” He said 3,000 chimneys, assuming a 50% conversion rate from methane to those lower-carbon gases, would draw down the equivalent of two billion tonnes of carbon dioxide per year.
A serious obstacle to the chimney idea: money. The project is now stalled at the prototype stage because no investor is yet willing to put money into an intermediate stage.
Affirming the “need for speed” as numerous terrifying climate tipping points approach, Durwood Zaelke, founder and president of the Washington, DC-based Institute for Governance and Sustainable Development, called for policy directives to support methane removal, citing the Montreal Protocol on atmospheric ozone depletion as an inspiration.