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Ecosystem, climate change and the right balance
Lund University
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Fig. 1 The European farmer can help to balance the European CO2-emissions by growing forest for energy production (e.g. through burning the yearly
biomass accumulation) on his land |
Ecosystems and associated industries will be hugely affected by climate change.
Some areas will become drier and others more humid, which of course will impact
on farming conditions. Some regions will be windier which will affect the forest
industry.
The exchange of greenhouse gases (e.g. CO2 and methane) between the
atmosphere and the land is two-way. During the 1980s and 1990s, land
ecosystems absorbed about one-third of the global anthropogenic emissions of
CO2.
Substantial research is being carried out to achieve a better understanding of
these dynamics. One important aim is to provide information on the future of
ecosystems relevant for policymakers, such as high-risk flood areas and good
opportunities for growing particular crops.
Research methods include quantification of greenhouse gas and energy flows
between the biosphere and the atmosphere, for example by flux towers, and
monitoring the state of the biosphere from satellites by remote sensing. The
Department of Physical Geography and Ecosystems Analysis in Lund has been
a major actor within the fields of measuring greenhouse gas exchanges, remote
sensing, and the development of computer models to predict future impacts on
ecosystems, from individual forest sites to the whole globe.
More in the North, less in the South
Results suggest considerable increases in net primary productivity (production
of new biomass), specifically the fixation of CO2 in new biomass in northern
countries and at high altitudes (Fig. 1). In these areas, a warmer climate increases
the length of the season for vegetation growth, and tree lines extend northwards
and upwards. Elevated levels of CO2, a limiting resource for plant life, also promote
increased biomass accumulation through a CO2 fertilisation effect. These changes
may therefore be positive for the forestry sector and agriculture in Scandinavia,
and they show a potential for increased carbon uptake, which could for be used
for accounting purposes within the Kyoto protocol.
However in other parts of Europe particularly western and southern Europe, along
with some dry continental areas in the East, the model projected lower-thanpresent
productivity. Productivity decreases were caused by less water availability
and, in some areas, extensive droughts, even though elevated CO2 may alleviate this because of better water
use efficiency. In drier areas,
particularly the Mediterranean,
there is an increased risk of forest
fires.
| Fig. 2. Average changes in vegetation productivity (yearly biomass accumulation) between the end of the last century and 2100
for three climatic zones in Europe. Changes were projected with an ecosystem model, which was driven with two regional climate
models and two IPCC emission scenarios (A2 and B2). The histogram bars in the different diagrams show the uncertainty in these
estimates that is related to the use of different combinations of climate models and emissions scenarios. |
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Lund also analysed modelled
changes in the CO2 uptake by
ecosystems. These are the net
outcome of CO2 uptake through
vegetation and CO2 releases
to the atmosphere through
decomposition processes in the
soil. Model results suggest a slight
increase in carbon stocks on
land during the next century. The
average projected carbon sink per
year was, however, less than 2% of
the current yearly emission of CO2
by European countries. Depending
on the climate scenario, the
results ranged from a small source
of carbon to the atmosphere to
an uptake of about 5% of the
emissions. This suggests that
land ecosystems are unlikely to
sequester a considerable fraction
of the European emissions in the
future. Changes in land use, for
example replacement of food
crops by biofuel crops, or planting
forest on agricultural land, could
lead to an additional carbon sink.
Land use and forest management
were kept constant in these
simulations. Projections of future
land use changes suggest there
will be surplus agricultural land
in Europe. This surplus land could
provide an opportunity to sequester more carbon through changes in land
management. If we want to maximise the CO2 uptake, we should plant energy
forest (Plate 1) there. The CO2 uptake in a Swedish energy forest is four to five
times more efficient compared to a normal Swedish coniferous forest. If the
European farmer were to plant an energy forest, this could potentially help
balance the European CO2-emissions. Furthermore, governmental financial
assistance could make this a reality.
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