Durwood Zaelke: Short-term Climate-Change Solution

October 13, 2009

Climate Change: Addressing Non-CO2 Climate Forcers Can Buy Some Time

Reducing such non-CO2 climate-change agents as black carbon (soot), tropospheric ozone, methane, and hydrofluorocarbons (HFCs), as well as expanding bio-sequestration, can forestall fast-approaching abrupt climate changes, according to a paper published today in the Proceedings of the National Academy of Sciences (PNAS).

Durwood Zaelke

Durwood Zaelke, co-director of the Bren School Program on Governance for Sustainable Development, joined lead author and Nobel Laureate Mario Molina and others in producing the paper, "Reducing Abrupt Climate Change Risk Using the Montreal Protocol and other Regulatory Actions to Complement Cuts in CO2 Emissions." The authors say that cutting non-CO2 climate-change agents could delay by approximately forty years the time when the dangerous threshold of 2 degrees Celcius (3.6 degrees Fahrenheit) of warming is reached, according to a press release issued by UC San Diego (UCSD).

"By targeting these short-term climate forcers, we can make a down payment on climate and provide momentum going into the December negotiations in Copenhagen," said Zaelke. "The Obama Administration and other key governments need to take up the fast-action climate agenda before it is too late." The authors said that pursuing these solutions could impact the character of the United Nations conference on climate change, set for December in Copenhagen, Denmark.

"Cutting HFCs, black carbon, tropospheric ozone, and methane can buy us about 40 years before we approach the dangerous threshold of 2°C (3.6°F) warming," said co-author Veerabhadran Ramanathan, a professor of climate and atmospheric sciences at Scripps Institution of Oceanography at UCSD.

The authors write that HFCs, powerful greenhouse gases that were developed as substitutes for ozone-depleting chlorofluorocarbons (CFSs) and are expected to account for up to 19 percent of atmospheric GHGs by 2050, are a good place to begin because they can be controlled under the existing Montreal Protocol. That treaty was developed after Molina sounded the alarm on the damage to Earth's ozone layer being caused by CFCs.

"The protocol is critical for avoiding abrupt climate change," said Molina, a UCSD professor of chemistry and biochemistry. "We have to take advantage of the proven ability of this legally binding treaty to quickly phase down HFCs." The paper points out that alternatives for HFCs have already been developed and need only the right regulatory incentive from the Montreal Protocol to be deployed.

The authors point out other "fast-action" strategies for averting rapid climate change, including the reduction of black carbon. The aerosol produced largely from the incomplete combustion of diesel fuels and biofuels, and from biomass burning is now considered to be the second or third largest contributor to climate change and is responsible for nearly half of the 1.9C (3.4F) increase in warming of the Arctic since 1890.

Researchers consider black carbon an ideal target for achieving quick mitigation because it remains in the atmosphere a few days to a few weeks and can be reduced by expanding the use of diesel particulate filters for vehicles and clean-burning or solar cookstoves.

Reducing black-carbon emissions worldwide by 50 percent could delay the warming effects of CO2 by one to two decades while greatly improving the health of those living in heavily polluted regions, Ramanathan said.

One biosequestration strately involves biochar technology, which captures CO2 through plant photosynthesis. The captured carbon is then converted into a stable substance similar to charcoal, called biochar, which can be used to replenish carbon sinks while acting as a fertilizer in soiles.

"Cutting CO2 emissions is essential, but it won't produce cooling fast enough to avoid passing tipping points for abrupt climate change," Zaelke added. "With the world already committed to more than two degrees Centigrade of warming, we need these fast-action strategies to put the brakes on climate change, and in the case of biochar, put us in reverse by reducing existing atmospheric concentrations of CO2....To back away from the cliff of abrupt climate change, we need biochar."

Read the complete release.

Read the paper.