Press release from ERL: 2 readings 1. 2.

Motivation Ships are strong sources of greenhouse gases and air pollutants: 3% of global CO 2 emissions ±13% of global NO x emissions (5-20%) ±12% of global SO 2 emissions IMO, 2014

Motivation Shipping sector shows a degree of awareness Claims to be a relatively clean mode of transportation Reduce emissions by speed reductions and other measures Ship CO 2 efficiencies

Motivation Legal framework to reduce ship emissions slow in making IMO initiatives to implement NECA and SECA Implemented in US waters in

Very few measurements on open sea OMI overpass time: 13:40 hrs

Estimating NO x emissions from NO 2 observations Lifetime of NO 2 at noon is generally short (few hours) Close relationship between NO x emissions and local NO 2 columns Simple mass balance approach (Martin et al. [2003]): Practical difficulties: 1.Standard CTM chemistry not appropriate for plumes 2.Emissions may be misplaced (E apriori ) 3. E apriori :N CTM varies in time and space (non-linear local chemistry) 4.Smearing, weak signal (poster Huan Yu) NO 2 column measured by OMI NO 2 column simulated by CTM Emission inventory used in CTM

1. Account for plume chemistry in GEOS-Chem GEOS-Chem plume-in-grid approach for ship emissions Higher OH in early stages of the plume Improved simulations with plume-in-grid show 50% lower NO x concentrations than instant dilution! Vinken et al., ACP, 2011 OHNO2 t

2. Detecting emission patterns with OMI OMI shows that EMEP emissions are misplaced (2.5 Tg NO 2 ) (3.7 Tg NO 2 )

3. Account for non-linear chemistry in providing constraints on emissions Satellite Model β describes local, monthly mean clear-sky sensitivity of NO 2 columns to (changes in) NO x emissions (Lamsal) For clear-sky European Seas: β = (0.7)

4. Avoid smearing Select days without clouds and without outflow of continental pollution

NO x emission estimates ships in Europe: 2005 before OMI top down inventory (0.9 Tg N/yr)

Changes in ship NO x emissions over European Seas (in TgN yr -1 ) 4 lanes represent 30% of European shipping NOx emissions Estimates mostly based on Spring & Summer observations Increase from , then decrease in 2009

NO x pollution from ships increasing in relevance Annual changes in NO x emissions ( ) Changes inferred from OMI by Curier et al. [2014] Changes inferred from OMI in this work

Comparison to changes in economic indicators No net change in European ship NOx emissions between 2005 and 2012 Increase in share of shipping sector to NOx emissions from 1 in 9 to 1 in 7

Slow steaming? Economic recession in Autumn 2008; shipping sector responded Cutting costs by saving on fuel Reducing overcapacity (less demand) Slow steaming: Reducing vessel speed from knots to knots This would reduce CO 2 and NO x emissions

Slow steaming observed from space 1. Long-term data set ( ) of ship presence detected by satellite altimeter instruments 2. Registration of the number of ships passing the Suez Canal

Slow steaming from space: Mediterranean Sea

Slow steaming from space Number of ships through the Suez Canal relatively constant Number of ships detected over Mediterranean increases Indication for a longer residence time in the Mediterranean Ratio Suez : altimeter ~ ship speed Ratio OMI NOx : altimeter ~ per ship emission factor Normal (20-25 knots; 37 – 46 km/hr)Slow steaming (14-20 knots; 25 – 37 km/hr)

Summary OMI allows detection of ship emissions on open sea European ship NOx emissions increased from Back at their 2005 levels in 2012 (in line with trade) Because land-based emissions decreased by 25%, ship emissions now make up a larger fraction (1 in 7) of European NOx emissions Direct evidence of slow steaming from altimeter in combination with Suez Canal passages Ship speeds reduced by 30% in the Mediterranean Accompanied by large NO x emission reductions 21 st century ECA’s will be enforced in 2016 Demand will increase Oil will still be used as fuel