Upon his first bicycle commute in California, Scot Miller, an assistant professor at Johns Hopkins University, encountered a curious sight: homes enshrouded in what appeared to be circus tents. This spectacle, unfamiliar to Miller, a North Dakota native, turned out to be a common termite fumigation practice in California, involving the use of sulfuryl fluoride.
This colorless, odorless gas, while effective at exterminating pests, has emerged as a potent, yet largely unregulated, greenhouse gas that lingers in the atmosphere for decades, complicating California’s climate mitigation efforts.
A recent study spearheaded by Miller and a collaborative team from Johns Hopkins and other institutions reveals California as the principal emitter of sulfuryl fluoride in the United States. Despite its application being monitored, its emissions remain unchecked, posing a significant challenge to the state’s ambitious environmental goals.
Jonathan Evans from the Center for Biological Diversity emphasizes the urgency of addressing this issue to maintain California’s leadership in climate action.
Research conducted between 2015 and 2019 by the National Oceanic and Atmospheric Administration’s Global Greenhouse Gas Reference Network uncovered that a staggering 60% to 85% of the U.S.’s emissions of this gas originate from California, particularly from Southern California and the Central Valley.
These areas’ susceptibility to drywood termites and their dense population and housing likely contribute to the high usage of sulfuryl fluoride for structural fumigation and agricultural applications.
Despite its relatively low atmospheric concentration compared to other greenhouse gases, sulfuryl fluoride’s warming potential is alarmingly high, over 4,600 times that of carbon dioxide on a century scale. This concern is amplified by its dramatic increase in atmospheric presence, escalating from 0.3 parts per trillion in 1978 to about 3 parts per trillion in 2023.
Its introduction succeeded the phasing out of methyl bromide, a substance detrimental to the stratospheric ozone layer, under the Montreal Protocol.
The persistence of sulfuryl fluoride use, despite alternatives like thermal pest eradication, is attributed to its unmatched efficacy in eliminating pests under fumigation tents. However, the environmental cost of this practice has led entities like the Center for Biological Diversity to petition for its regulation and eventual phase-out, a plea that has yet to find favor with the California Air Resources Board.
This situation underscores a broader environmental challenge: the need for comprehensive strategies that address all sources of greenhouse gas emissions, not just the predominant ones like carbon dioxide and methane.
As Jens Mühle, an atmospheric chemist and study co-author, suggests, achieving significant emissions reduction requires a collective effort, acknowledging the cumulative impact of various greenhouse gases, including those like sulfuryl fluoride that have flown under the radar.
California’s endeavor to reconcile its termite control measures with its climate objectives highlights the complex, multifaceted nature of environmental stewardship. As the state continues to navigate these challenges, the global community watches and learns, recognizing that the path to sustainability involves addressing both the conspicuous and the overlooked contributors to climate change.