New insights into a complex atmospheric chemistry problem
Climate change and air quality are two significant challenges that Europe must address head on. But doing requires more than innovative solutions. It also requires in-depth research and careful planning to ensure our climate actions actually solve the problem and not create unintended consequences. Take for example atomic chlorine, a chemical element whose role in atmospheric chemistry is the topic of much debate. According to Pete Edwards, an analytical atmospheric chemist at the University of York(opens in new window), quantifying chlorine’s atmospheric impact is a prerequisite to developing effective tools for managing the climate crisis. “With several proposed tools looking to geoengineer the atmosphere, it is critical that chlorine be better represented in the models we use to evaluate a solution’s impact,” he says. Advancing our ability to represent these processes is the EU-funded Trop-ClOC project. The project, which received support from the European Research Council(opens in new window) (ERC), aims to advance our understanding on atomic chlorine’s role as an atmospheric oxidant – a task that includes quantifying its contribution to climate change and air pollution. “We set out to push the state of the science and to do so by developing new observational evidence that can challenge how chlorine is represented in our current atmospheric chemistry models,” adds Edwards, the project’s principal investigator.
Predicting the impact chlorine has on air pollution
To start, the project developed new optical instrumentation and sampling methods that they then used to collect data on, for example, hydrochloric acid (HCl). Not only is HCl the largest chlorine reservoir compound, it’s also notoriously difficult to detect. “With our instruments, we can now measure HCl with high accuracy and precision and minimal inlet losses or interactions – greatly increasing our ability to quantify and understand this important reservoir of atmospheric chlorine,” explains Edwards. According to Edwards, understanding the drivers of HCl in the troposphere is a key to being able to predict the current impact of chlorine on air pollution and the removal of the climate gas methane. “It is also essential if we are to ensure there are no unintended consequences from proposed geoengineering solutions to climate change, some of which involve significantly increasing chlorine in the troposphere,” he adds.
Flagging misrepresentations in atmospheric processes
While researchers continue to analyse the collected data, they have already identified several processes that are misrepresented in current models. For instance, in Bermuda, they identified misrepresentations of atmospheric heterogeneous processes in marine locations – a misrepresentation that could result in significant underestimations of the true role of atmospheric chlorine chemistry. To fully understand this issue, along with other uncertainties identified during the project, the project team is currently making additional measurements using Trop-ClOC instrumentation. They are also exploring the possibility of additional EU-funded projects that could expand on Trop ClOC’s groundbreaking work. “The ambitious nature of Trop-ClOC means its legacy will come from the new technologies demonstrated, the novel datasets collected, and the fundamental advances made in how we understand this complex atmospheric chemistry problem,” concludes Edwards.
