Agriculture Reference
In-Depth Information
Within the scientific mainstream there is little consensus as to whether soil carbon se-
questration can only have a minor impact upon our overall greenhouse gas emissions, or
whether it has the potential to solve all our problems. One scientific paper, authored by
nine scientists, states that 'the IPCC estimates for the global mitigation potential of carbon
sequestration in agricultural soils are 0.4 to 0.6 billion tonnes per year (over 100 years) -
which is less than ten per cent of our current annual carbon emissions from fossil fuels …
From this perspective, soil carbon sequestration can make only modest contributions to the
overall need for mitigation of atmospheric CO 2 build-up.' 8 Yet a year later, one of the nine
authors, Dr Rattan Lal - who is the world's number one guru on soil carbon, and frequently
cited by the IPCC - stated that 'the maximum potential rate of Soil Organic Carbon (SOC)
sequestration of three billion tonnes of carbon per year is high enough to almost nullify the
annual increase in atmospheric concentration of CO 2 at 3.4 billion tonnes per year.' 9
A perusal of the mainstream scientific literature on soil carbon sequestration suggests
that livestock may have something to offer, but perhaps not a lot. Land which is grazed
usually sequesters more carbon than land which is cultivated - hence Harvey's enthusiasm
for replacing intensive grain growing with grazing. But grazed land is usually less product-
ive than cultivated land, so the conversion of arable land to pasture would either require the
reverse taking place somewhere else, or else a decline in livestock numbers and meat-eat-
ing. By and large (though by no means always) woodland sequestrates more carbon than
pasture. According to studies carried out by Pete Smith and others at Aberdeen University,
a system of farming similar to that described in the Organic Livestock scenario described
in Chapter 9 in which a third of the EU's arable land was put into ley-arable rotation, would
increase total soil carbon stocks by 39 million tonnes per year. Putting a similar area of land
over to forest would increase soil and wood carbon stocks by 49 million tonnes. But these
figures represent only 4.27 and 5.41 per cent of all the CO 2 produced annually in Western
Europe. 10
The FAO in Livestock's Long Shadow conclude 'the potential for incremental accumu-
lation of organic carbon in soils is huge and adapting extensive livestock systems is the
key to unlocking this potential.' 11 They even recommend including 'soil carbon as a class
of offset credits for greenhouse gas emissions trading.' 12 But on further reading it looks
as though 'adapting extensive livestock' means 'reorienting extensive grazing towards the
provision of environmental services', which in turn may be a euphemism for restricting it:
Carbon sequestration, through adjustments in grazing management or abandon-
ment of pastures will also be difficult, but given the potential of the world's vast graz-
ing lands to sequester large amounts of carbon and reduce emissions, mechanisms
must be developed and deployed to use this potentially cost-effective avenue to ad-
dress climate change … Grazing access will have to be restricted and managed, often
 
 
 
 
 
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