Climate scientist James Hansen has warned that humanity’s reliance on aerosols to offset greenhouse gas emissions may have masked the true extent of global warming. A new analysis by Hansen and his colleagues suggests that a decline in air pollution, particularly from shipping fuels, could be responsible for record-breaking temperature spikes over the past two years.
The researchers used data from a 2020 regulation that reduced sulphur emissions to estimate the climate effects of aerosols with more precision. Their findings indicate that the drop in shipping aerosols increased the heat reaching Earth by 0.5 watts per square metre, an effect equivalent to a decade of global carbon dioxide emissions at current levels.
This discovery raises concerns about the true extent of greenhouse gas warming and suggests that air pollution’s cooling effect may have been masking the full impact of our emissions. Hansen and his colleagues argue that this means the climate is more sensitive to rising greenhouse gas levels than previously thought, increasing the risk of climate tipping points such as the slowdown of Atlantic Ocean currents and the collapse of the West Antarctic ice sheet.
However, not all scientists agree with the researchers’ conclusions. Gavin Schmidt at NASA says the estimated warming effect may be an overestimate due to assumptions about other changes in air pollution or natural variability. Further research is needed to reconcile different estimates of the warming effects of aerosols.
Source: https://www.newscientist.com/article/2466828-is-cleaner-air-accelerating-global-warming-more-than-we-expected