Bridges Trade BioRes • Volume 9 • Number 21 • 27th November 2009

New Study Claims Sulphur Emissions Cuts Could Accelerate Global Warming

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Sulphur dioxide emissions from bunker fuels used in ships have helped to decelerate the rate of climate change, a new study suggests. However, the authors caution that due to its harmful effects on sulphur on human health, the use of sulphur in shipping emissions to promote ‘climate cooling’ is not advisable.

Jan Fuglestvedt, of the Center for International Climate and Environmental Research Oslo (CICERO), said that “so far shipping has caused a cooling effect that has slowed down global warming.”

Releasing sulphur dioxide into the atmosphere allows for the creation of clouds by supplying tiny seeds around which water droplets form. Sunlight then bounces off of the white tops of these clouds, resulting in a cooling effect.

Some scientists have proposed releasing sulphur in the upper atmosphere in order to shelter the Earth from sunlight and slow global warming. This has been one of many suggestions for deliberate ‘geoengineering’ to adjust the climate system. Nevertheless, scientists have warned against such methods, calling attention to the health risks to humans involved in sulphur pollution.

According to a previous study, in 2001 toxic sulphur dioxide produced by burning bunker fuel, used in aviation and shipping, accounted for the deaths of roughly 60,000 people around the world. The study linked the pollutant to cancer and heart and lung disease and said that a cut in sulphur emissions would have a positive effect on human health.

Other scientists have argued that decreasing sulphur pollution from ships would result in a ‘double warming’ effect: less pollution allows more sunlight to reach the planet’s surface resulting in a rise in carbon dioxide (CO2) emissions. Since shipping comprises approximately 3.3 percent of global (CO2) emissions already, the UN Climate Panel says an increase in this pollutant would trigger more floods, rising sea levels, heat waves, droughts, and disease.

Fuglestvedt’s study conversely argues that it would take some 70 years for the shipping industry to evolve into a net contributor to global warming if sulphur dioxide emissions were immediately reduced by 90 percent, with all other fuel-related emissions remaining at 2000 levels.

The International Maritime Organisation (IMO) is seeking a reduction in the sulphur content of bunker fuel to a maximum of 3.5 percent by 2012, followed by a further decrease to 0.5 percent by 2020. Participants in the UN climate summit in Copenhagen in December will also deliberate over new measures to penalise CO2 emissions in both the international aviation and shipping industries.

ICTSD Reporting; “Curbs To Ship Pollution Would Stoke Global Warming, Study Says,” REUTERS, 23 November 2009.