In May 2015, the International Maritime Organisation (IMO) agreed upon a universal definition of ‘black carbon'. The definition will allow the IMO to develop ways of measuring black carbon emissions, and environmentalists and NGOs are hoping this signifies a first step in reducing emissions, particularly in the Arctic.
1. What is black carbon?
Black carbon is the second major contributor to climate change after CO2. Black carbon refers to solid particles emitted during the incomplete combustion of fossil fuels, biofuels and biomass. Therefore these particles are emitted from diesel engines, cooking stoves, wood burning and forests fires, and are what gives soot its black colour. When suspended in air, black carbon absorbs sunlight, generating heat in the atmosphere, which then warms the air and can affect regional cloud formation and precipitation patterns.
2. How does it affect the environment?
Black carbon gives clouds a darker colour, reducing their albedo or ability to reflect light back into the atmosphere, and therefore creates a greater warming effect. Black carbon has approximately a million times more heat-trapping power than CO2.
The arctic environment is particularly sensitive to black carbon emissions due to their capacity to increase surface temperatures, and accelerate snowmelt.
However, as black carbon has a short atmospheric lifespan (remaining in the atmosphere for only a few weeks), targeted strategies to reduce black carbon emissions are expected to provided climate benefits within the next few decades.
3. How is the Shipping Industry involved in the issue of black carbon emissions?
A working paper published by the International Council on Clean Transportation (ICCT) found that diesel fuel from ships contributed approximately 7-9% of global diesel black carbon in 2000. By 2010, the contribution had risen to 8-13%, with scientists predicting an increase in levels of black carbon in the Arctic in particular as human activity in the region rises.
4. Are emissions of black carbon being regulated?
Black carbon is not currently regulated as a pollutant. However, as it is found within particulate matter and sulphur oxides found in fuel oil, it is indirectly regulated through Regulation 14 of MARPOL Annex VI. Black carbon will also regulated indirectly when the Emission Controlled Areas regulation places a 0.5% limit on sulphur emissions, requiring the use of either low-sulphur fuels, or abatement technology globally.
As Ship and Bunker predict, the recently IMO-approved black carbon definition is likely to drive further research into the impacts of black carbon, potentially bringing about future black carbon emission regulations.
5. How can ship owners mitigate their black carbon emissions?
The ICCT working paper suggests the use of diesel particulate filters, liquefied natural gas, scrubbers, and low-sulphur fuels (LSF) can reduce shipping emissions of black carbon by up to 70 %. Reduced fuel consumption techniques – such as sailing at slower speeds, with maximum loads to reduce the number of journeys – are also recommended in reducing black carbon emissions.
It is thought that black carbon emissions are related to the combustion efficiency of an engine. For example, diesel engines with high combustion efficiency are found to result in relatively low black carbon formation, even then burning a low grade quality fuel. A range of abatement technologies are also considered in the CIMAC working paper.
Resource adapted from the Ship and Bunker Fathom Spotlight on Black Carbon (August 3, 2015)
Shared by Carolyne Okeijn
Image credit: tpsdave / pixabay