A new study published in the journal of Atmospheric Chemistry and Physics has found that a large increase in Arctic shipping could exacerbate global warming by 17% to 78%. The range is so wide because of the uncertain future of shipping in the High North, which depends on changes in vessel traffic, growth, and shipping routes. Diesel-burning ships do not completely oxidize carbon, thereby emitting black carbon. This byproduct is a pollutant that hastens ice and snow melt by absorbing sunlight, which increases the albedo of the surrounding area. Black carbon is more detrimental in the Arctic than in other places because it absorbs both direct sunlight and that which is reflected off of snow and ice.

The study takes a detailed look at Arctic shipping, breaking down the vessels into multiple categories and charting each category’s growth throughout the seasons and over the next  half century. For instance, while container ships only made up 21% of maritime traffic in the Arctic in 2004, based on data from the second IMO GHG Study in 2009, they could make up 61% of ship traffic in 2050 under a high-growth scenario. The study also predicts that the amount of international shipping traffic diverted to the Arctic could reach 5% by 2050 under high-growth scenario (or 1.8% in a “business-as-usual” situation). The more traffic diverted to the Arctic, the greater the emissions will increase without any regulation. One upside of the findings is that if maximum feasible regulatory controls are put in place, black carbon amounts could be held steady through 2050.

The paper, written by Dr. James Corbett, a professor of marine policy at the University of Delaware, along with a team of scientists from NOAA, the University of Colorado, Boulder, and various institutions in Canada, can be read online here (PDF, no subscription required).

Abstract: This paper presents 5 km×5 km Arctic emissions inventories of important greenhouse gases, black carbon and other pollutants under existing and future (2050) scenarios that account for growth of shipping in the region, potential diversion traffic through emerging routes, and possible emissions control measures. These high-resolution, geospatial emissions inventories for shipping can be used to evaluate Arctic climate sensitivity to black carbon (a short-lived climate forcing pollutant especially effective in accelerating the melting of ice and snow), aerosols, and gaseous emissions including carbon dioxide. We quantify ship emissions scenarios which are expected to increase as declining sea ice coverage due to climate change allows for increased shipping activity in the Arctic. A first-order calculation of global warming potential due to 2030 emissions in the high-growth scenario suggests that short-lived forcing of ~4.5 gigagrams of black carbon from Arctic shipping may increase global warming potential due to Arctic ships’ CO2 emissions (~42 000 gigagrams) by some 17% to 78%. The paper also presents maximum feasible reduction scenarios for black carbon in particular. These emissions reduction scenarios will enable scientists and policymakers to evaluate the efficacy and benefits of technological controls for black carbon, and other pollutants from ships.

News Links

“Arctic shipping will hasten ice melt, study says,” The Guardian

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