World soil demand
Removal of carbon dioxide from the atmosphere can be
achieved either mechanically or through biological means.
Mechanical removal, referred to as carbon capture and storage
(CCS), entails the collection of CO
2
emissions from fossil fuel
at concentrated sources such as power stations and cement
plants and their storage in geological formations such as spent
Human needs Ecosystem conservation
oil fields (IPCC 2005). Biological mechanisms exploit the abil-
ity described above of photosynthesising organisms to capture
CO
2
and store it as biomass or as organic matter in sediments
of various kinds.
desertification
climate
The biological management of carbon in tackling climate
control
change
food
change has therefore essentially two components: the reduc-
water biodiversity
mitigation
security
natural tion in emissions from biological systems and the increase in
quality
urbanisation
archive
their storage of carbon. These can be achieved in three ways:
existing stores could be protected and the current high rate of
N2O
gene pool
reduction
loss reduced; historically depleted stores could be replenished
purification
reservoir
habitation by restoring ecosystems and soils; and, potentially, new stores
carbon
sequestration
could be created by encouraging greater carbon storage in ar-
aquifer
recharge
recreation
species
CH
eas that currently have little, for example through afforestation.
4
adaptation
oxidation In this report, we consider the roles that natural and human-
fibre
filtration nature dominated ecosystems can play in reducing emissions and in
conservation
ecosystem
removing carbon from the atmosphere and we refer to the lat-
waste
restoration
ter as ‘biosequestration’.
crop
disposal
production
soil quality
livestock
improvement
infrastructure
If well designed, a biological approach to carbon management
feed
food
can offer other benefits. Natural ecosystems, especially forests,
quality
are often rich in biodiversity as well as carbon; protecting one
may serve to look after both (UNEP-WCMC 2008; Miles and
Source: Lal, 2007.
Kapos 2008); they may also offer a range of other ecosystem
services such as soil stabilisation, local climate amelioration
STABILISING OR REDUCING THE AMOUNT and recycling of waste products. Good management of these
OF ATMOSPHERIC CARBON ecosystems, and of agricultural systems, can pay dividends in
Stabilising or reducing the amount of atmospheric carbon can terms of water and nutrient availability and reversal of land
be achieved in essentially two ways: by reducing the rate of emis- degradation, having positive impacts on livelihoods and help-
sion, or by increasing the rate of absorption. Any successful strat- ing in poverty reduction (Lal 2007; Smith et al. 2007a).
egy is almost certain to need both approaches, and will require
contributions from all sectors (Cowie et al. 2007; Eliasch 2008). That is not to say ecosystem carbon management is straight-
forward. There are serious technical, social and economic
Reduction in emissions can be achieved through a reduction challenges and some risks of unintended consequences. This
in fossil fuel use, in cement production or in adverse (that is report examines the state of knowledge about both its potential
carbon-releasing) land-use change, or a combination of these. and challenges.
13
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