12.02.2010

Four fast-action strategies to tackle abrupt climate change

Quelle: European Commission

Research has indicated that current emissions of greenhouse gases (GHGs) have committed the planet to an increase in global temperature that could lead to abrupt climate change. International climate policy, such as the Kyoto Protocol, has focused on long-term reductions in CO₂ emissions but more urgent and rapid mitigation may also be needed.

The research examined four available 'fast-action' mitigation strategies that could be initiated within 2-3 years, be implemented within 5-10 years, and produce the required climate response within decades. They have been recommended because they complement CO₂ reduction measures and can be streamlined into existing policies and agreements.

Hydrofluorocarbons (HFCs) are predominantly used as refrigerants as replacements for chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and halons, which are being phased out by the Montreal Protocol due to the harm they cause to the stratospheric ozone layer¹. Although they do not have ozone-depleting properties, HFCs still have a high global warming potential and, without regulation, the projected HFC emissions in 2050 could have the equivalent impact on global warming of 9-19 per cent of business-as-usual CO₂ emissions. The research suggests that the Montreal Protocol could be applied effectively and efficiently to reduce production and consumption of HFCs.

Black carbon (soot) is emitted from incomplete combustion of fossil fuels and biomass. It is estimated to be either the second or third most significant warming agent, although the extent of its impact is uncertain. Black carbon causes warming by absorbing solar radiation in the troposphere and darkening snow and ice to reduce reflection from the planet's surface. The research suggested black carbon emissions could be reduced through increased use of existing technologies which reduce emissions from diesel combustion and cooking stoves as well as through amendments to existing regulations, for example, on maritime pollutant emissions and air quality.

Ozone in the first 10-15km above ground (also known as tropospheric ozone) is a significant GHG and is toxic to humans and plants. It is formed when pollutants, such as carbon monoxide, methane, nitrogen oxides and volatile organic compounds, react in the presence of sunlight. Rigorous global implementation of air pollution regulations and available technologies could reduce carbon monoxide and nitrous oxide emissions by more than 50 per cent, which would in turn reduce tropospheric ozone levels by 10 to 20 per cent.

Biosequestration is the direct removal of CO₂ from the atmosphere through land-use change, afforestation, reforestation, and practices that enhance carbon storage in landfills and soils. The research particularly highlighted biochar production, which converts carbon in plants into a stable charcoal-like substance by burning plant matter in an oxygen-reduced atmosphere (pyrolysis). It is estimated that, using only waste biomass, biochar has the potential to mitigate 3.67 Gt of CO₂ emissions per year by 2040.

A comprehensive climate policy could benefit from incorporating these 'fast-action' strategies. Some could be streamlined into existing policy, such as an HFC phase-down under the Montreal Protocol, and some would benefit from a market-based approach, such as biosequestration. Strong compliance mechanisms would help ensure their success.

Further information:

(1) See http://ec.europa.eu/environment/ozone/international_action.htm

Source: Molina, M., Zaelke, D., Madhava Sarma, K. et al. (2009). Reducing abrupt climate change risk using the Montreal Protocol and other regulatory actions to complement cuts in CO2 emissions. Proceedings of the National Academy of Sciences. 106(49): 20616-20621.

Contact: dzaelke@igsd.org