Climate Change, Grazing & Land Use March 2020
There is now a new Climate change & land use section of my website.
There is a lot of talk in conservation circles and the media on the impact of
land use on climate change. However it is a complex subject and it would
appear that carbon flows are not understood by most; for example the
difference between carbon emissions from the use of fossil carbon and
carbon emissions which are merely recycling of atmospheric carbon.
When we burn fossil fuels we are adding new carbon to the atmosphere, the
cause of global warming. However when animals belch methane this does
not result in an increase on atmospheric carbon: they are merely recycling the
carbon fixed by the plants they eat. Certainly the methane they belch is a
strong greenhouse gas, but its time in the atmosphere is short compared to
the main greenhouse gas, carbon dioxide.
Animal husbandry, particularly intensive farming, certainly does release a
new greenhouses to the atmosphere but this is through the use of fossil
carbon in transport, farm machinery, fertiliser & pesticide production, and the
processing of animal feed. However most of these outputs will also apply to
crop growing as currently managed. The only way to reduce these carbon
outputs is replacement of fossil fuels with renewable energy, with no input of
fertilisers dependent on fossil fuels for their manufacture. Otherwise moving
to a vegetarian diet will not make much difference to the climate! Certainly
replacement of tropical rainforest to animal pasture in some parts of the
world does add to the amount of carbon in the atmosphere, but this is not
relevant to UK farming.
In the UK before the advent of the industrial manufacture of fertilisers,
animals were an essential part of crop rotation, the dunging effect of animals
being essential to maintain long-term soil fertility. If animals are no longer
part of the farming scene, then soil fertility can only be maintained through
the continual use of industrial-manufactured fertilisers (although the use of
legumes such as clover can fulfil the nitrogen deficit). Can these be produced
in a carbon-neutral way? The return to more environmentally extensive
farming does rely on animals.
Additionally, a significant proportion of the UK’s biodiversity is grazing-
dependent, such as chalk grassland, limestone grassland and lowland heath:
if animals are no longer part of the agricultural scene, then this biodiversity
will be lost. And does wool not have a bright future as a non-fossil fuel, non-
plastic textile?
Climate change mitigation & nature conservation not always on the
same side!
There appears also to be a strong belief amongst conservationists that
conservation of habitats and climate mitigation are always on the same side,
but there is no a priori reason why this should be the case! There are times
when, if we want to conserve the landscapes and natural habitats of the UK,
we will have to decide which is more important: climate mitigation or
preventing the loss of habitats.
The papers in the new Climate change & land use section of my website
address these issues, and also point out that tree planting in the UK does not
necessarily mitigate climate change.
A View from Argyll
James Fenton’s perspective
on current conservation issues
Click here for previous blogs
*October 2019*
James Fenton’s latest paper, first published
online at www.fenton.scot
9 October 2019
WOODLAND OR OPEN GROUND?
Scenarios for the persistence of woodland
in the presence of grazing
The Highlands of Scotland as an example
Note: I have recently added new papers to the peat-
land page. These consider the long-term dynamics of
ombrotrophic peatlands.
