Assessment of Near-Future Policy Instruments for Oceangoing Shipping: Impact on Atmospheric Aerosol Burdens and the Earth’s Radiation Budget

Abstract

We apply the global climate model ECHAM5/MESSy1-MADE with detailed aerosol and cloud microphysics to study the impact of shipping on tropospheric aerosol burdens, clouds, and the radiation budget for four near-future ship emission policy scenarios for the year 2012. We compare a "No Control" scenario with global sulfur limits and regionally applied reductions. We show that, if no control measures are taken, near surface sulfate increases by about 10-20% over the main transoceanic shipping routes from 2002 to 2012. A reduction of the maximum fuel sulfur (S) content allowed within 200 nautical miles of coastal areas ("global emission control areas") to 0.5% or 0.1% (5000 or 1000 ppm S, respectively) results in a distinctive reduction in near surface sulfate from shipping in coastal regions compared with the year 2002. The model results also show that if emissions of nitrogen oxides (NO x ) remain unabated, a reduction of the fuel sulfur content favors a strong increase in aerosol nitrate (NO 3 ) which could counteract up to 20% of the decrease in sulfate mass achieved by sulfur emission reductions. The most important impact of shipping on the radiation budget is related to the modification of low maritime stratus clouds resulting in an increased reflectivity and enhanced shortwave cloud forcing. The direct aerosol effect from shipping is small. Our study shows that one can expect a less negative (less cooling) radiative forcing due to reductions in the current fuel sulfur content of ocean-going ships. The global annual average net cloud forcings due to shipping (year 2012) are in the range of -0.27 to -0.58 W/m 2 with regional cooling occurring most over the remote oceans.

Aerosol indirect effects from shipping emissions: sensitivity studies with the global aerosol-climate model ECHAM-HAM

“…In their simulations, a reduction of the globally averaged fuel sulfur content from 2.7 % (in 2002) to 0.5 % (in 2012) lead to a reduction of globally averaged AIEs from shipping emissions from about −0.43 to about −0.27 W m −2 despite an annual growth rate of fuel consumption of 4.1 %. Applying a model environment completely identical to Lauer et al (2007) and Lauer et al (2009), Righi et al (2011 the shipping emission induced AIE to range from −0.40 to −0.28 W m −2 -despite the total assumed fuel consumption, and thus emissions, being higher than in Lauer et al (2007). Righi et al (2011) attribute this difference in obtained AIE to the use of a different geographical distribution of the shipping emissions.…”

“…spread-out about shipping corridors rather than concentrated along main shipping routes. Lauer et al (2009) tested the impact of future regulations regarding the sulfur content of marine bunker fuel (IMO, 1998). In their simulations, a reduction of the globally averaged fuel sulfur content from 2.7 % (in 2002) to 0.5 % (in 2012) lead to a reduction of globally averaged AIEs from shipping emissions from about −0.43 to about −0.27 W m −2 despite an annual growth rate of fuel consumption of 4.1 %.…”

“…This masking may be reduced due to shipping emission regulations (e.g. Lauer et al, 2009), but even without those policy regulations, the estimated current cooling effect of shipping emissions will switch to a long-term warming (e.g. Fuglestvedt et al, 2009).…”

Black carbon from ships: a review of the effects of ship speed, fuel quality and exhaust gas scrubbing

“…Shipping emissions also alter the radiative balance of the atmosphere via warming by CO 2 , ozone and BC emissions, and cooling by particulate sulfate formation and subsequent formation and alteration of clouds Lauer et al, 2009). Cooling can also result from ship NO x emissions reducing methane lifetime (Myhre et al, 2011).…”

The impact of shipping emissions on air pollution in the greater North Sea region – Part 1: Current emissions and concentrations

“…In contrast, measures to control ship emissions were disregarded for a long time. For a few years, however, the awareness of air pollution by shipping in particular concerning the emission of precursors for particulates has been rising (Eyring et al, 2005a, b;Lauer et al, 2009;Dentener et al, 2006), and political options to decrease ship emissions are being discussed. Ship traffic in the North Sea is now recognized by its adjacent states as a relevant source of air pollutants because future projections show that this traffic is likely to grow further during the coming decades (Project, 2014).…”