EMISSIONS AND SEQUESTRATION
– THE BINDING OF CARBON
Anthropogenic climate change is caused by the rising content of greenhouse gases and
particles in the atmosphere. Firstly by the burning of fossil fuels, releasing greenhouse
gases such as CO
2
, (“brown carbon”) and dust particles (part of “black carbon”); secondly
by emissions from clearing natural vegetation, forest fires and agricultural emissions, in
cluding those from livestock; and thirdly – by the reduced ability of natural ecosystems to
bind carbon through photosynthesis and store it – so called green carbon (Trumper et al.,
2009). The uptake of CO
2
into a reservoir over long (several decades or centuries) time
scales, whether natural or artificial is called carbon sequestration (Trumper et al., 2009).
Fact box 1. The colours of carbon: Brown, Black, Blue and Green
Climate Change has driven widespread appreciation of atmo- world’s oceans bind an estimated 55% of all carbon in living or-
spheric CO
2
as the main greenhouse gas and of the role of an- ganisms. The ocean’s blue carbon sinks – particularly mangroves,
thropogenic CO
2
emissions from energy use and industry in marshes and seagrasses capture and store most of the carbon
affecting temperatures and the climate – we refer to these emis- buried in marine sediments. This is called “blue carbon”. These
sions as “brown carbon” for greenhouse gases and “black car- ecosystems, however, are being degraded and disappear at rates
bon” for particles resulting from impure combustion, such as 5–10 times faster than rainforests. Together, by halting degradation
soot and dust. The Emissions Trading System of the European of “green” and “blue” carbon binding ecosystems, they represent
Union (EU-ETS) is a “black-brown carbon” system as it does not an emission reduction equivalent to 1–2 times that of the entire
incorporate forestry credits. The Kyoto Protocol’s Clean Devel- global transport sector – or at least 25% of the total global carbon
opment Mechanism (CDM) does in principle include forestry emission reductions needed, with additional benefits for biodiver-
credits, but demand (in the absence of a linking directive and sity, food security and livelihoods. It is becoming increasingly clear
demand from the EU-ETS) and prices have always been too low that an effective regime to control emissions must control the en-
to encourage success, so CDM has also become, for all practical tire “spectrum” of carbon, not just one “colour”.
purposes, another “black carbon” mechanism.
In the absence of “Green Carbon”, biofuel cropping can become
Terrestrial carbon stored in plant biomass and soils in forest land, incentivized, and can lead to carbon emissions if it is not done cor-
plantations, agricultural land and pasture land is often called “green rectly. The conversion of forests, peatlands, savannas and grass-
carbon”. The importance of “green carbon” is being recognized lands to produce food-crop based biofuels in Brazil, Southeast Asia
through anticipated agreement at the United Nations Framework and the United States creates a biofuel carbon debt by emitting 14
Convention on Climate Change Conference of the Parties (COP) to 420 times more CO
2
than the annual reductions in greenhouse
in Copenhagen, December 2009, which includes forest carbon gases these biofuels provide by replacing fossil fuels. In contrast,
– through various mechanisms, be they REDD and afforestation, biofuels produced from waste biomass and crops grown on de-
REDD-Plus, and/or others (e.g. ‘Forest Carbon for Mitigation’). The graded agricultural land do not accrue any such carbon debt.
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