Recently, new regulations drastically reduced the sulphur content in global shipping fuels by over 80%, significantly decreasing air pollution. This change, intended to improve air quality, has had the unintended consequence of accelerating global heating, as the reduced pollution particles no longer block sunlight or form clouds that mitigate warming. Recent research highlights the profound effects of this “termination shock” on the climate.
The Sudden Increase in Heat Trapped
Research led by Dr Tianle Yuan from the University of Maryland found that the cut in sulphur pollution led to an estimated 0.2 watts per square meter of additional heat being trapped at the Earth’s surface. This abrupt increase in trapped heat has contributed to a rise in global temperatures, potentially doubling the warming rate compared to the long-term average since 1880. The heating effect of the pollution cut is expected to last about seven years, equating to 80% of the total extra heating seen since 2020 from other long-term factors.
Mixed Scientific Views on Temperature Rise
While some scientists, including those behind the study, believe the pollution cut is a substantial factor in recent temperature increases, others are more sceptical. Dr Zeke Hausfather from Carbon Brief and Dr Gavin Schmidt from NASA’s Goddard Institute for Space Studies argue that feedback mechanisms in the climate system, not accounted for in simpler models, likely reduce the impact. They estimate the temperature rise due to the pollution cut to be significantly lower, with a more comprehensive analysis expected later in 2024.
Geoengineering Lessons and Risks
The reduction in shipping pollution has inadvertently acted as a large-scale geoengineering experiment, providing insights into the potential and risks of such interventions. While stimulating cloud cover through aerosol pumping could temporarily cool the Earth, this approach carries significant risks, including high temperature rises upon cessation (termination shock) and possible disruptions to global precipitation patterns. Dr Yuan emphasizes the need for more research into geoengineering as a temporary measure but stresses that it does not address the root cause of global warming—fossil fuel emissions.
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Source: The Guardian
