Marshall called the study "the most up-to-date survey of shipping emissions in the Arctic." He believes the research "can provide a firm foundation for policy makers trying to assess the impact of those emissions."
Growth Rate Influences Emissions Scenarios
Corbett and his colleagues began by producing an inventory of emissions from the 15,000 ship trips that occur annually in the Arctic. They used data from the year 2004, which came out of the Arctic Marine Shipping Assessment, an international study that catalogued the vessels based on type, fuel source and estimated emissions.
The next step was to model future scenarios for Arctic shipping: one involved a "business as usual" growth, and a second envisioned a fast expansion in the shipping industry.
Under the fast-growth scenario, by 2030 the addition of black carbon emissions
could increase the warming potential of the Arctic ships' CO2 by 17 percent to 78 percent.
Corbett cautioned that more research is needed to refine these numbers. What's more important is the potential for mitigation: in both scenarios, the researchers projected that control measures based on current technology could reduce black carbon-caused warming by 90 percent.
Similar reductions are being seen with technologies already being used in passenger vehicles, said Jacobson. New cars and buses often come equipped with traps that cut down on black carbon emissions by over 90 percent.
Still, Jacobson said, "it's probably not a technological issue." The real key lies in policy.
Over the past 3 years, Congress has seen four proposed laws on reducing black carbon. Two of the bills (The Arctic Climate Preservation Act and the Black Carbon Research Bill) never became law. Another bill (HR1760)—the —is being reviewed by the Subcommittee on Energy and Environment. The only successful bill was passed in 2009; it requires the EPA to research methods of reducing black carbon emissions.
Corbett hopes that his research will demonstrate the potential of mitigation. "[By adding] a controlled emission pathway like we have—it also adds to the value of future analysis," said Corbett. "Policy makers can immediately ask the question 'Would policy and intervention help?'"