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Atmospheric scientists agree that climate change is happening
and will soon become one of the most significant impacting
influences on the environment over the next century. Some
climate change is part of the natural order, but findings
compiled by the Intergovernmental Panel on Climate Change
provide evidence that the world is getting warmer, and in
mid-latitudes wetter, than could expected under natural cyclic
change. These changes, attributed largely to the emission
of the ‘greenhouse’ gases carbon dioxide, methane,
nitrous oxide and other man-made ones, are forecast to continue.
Ireland is one of the largest per capita emitters of greenhouse
gases due to car use, high energy consumption and a large
agricultural industry. Agriculture contributed ~35% of Ireland’s
greenhouse gas emissions in 1990. In fact agriculture is not
only contributing to climate change but will be potentially
impacted by it. The Environmental Protection Agency is funding
work undertaken at University College Dublin to examine both
the impacts and contributions of Irish agriculture to climate
change. Some of the potential impacts will be outlined here.
The simplest approach to predicting the impact of climate
change is to use knowledge to make informed judgments. A more
rigorous approach is to use the same knowledge, formalized
as mathematical models and to simulate what may happen in
the future. For both approaches it is necessary to have some
idea of what the future climate will be like. It is possible
to use global estimates and expected trends to deal with this
issue but preferably computer simulations of future global
weather will be used to obtain data specific to Ireland. The
problem that can arise with such data is that it usually represents
an area at least the size of Ireland as one homogeneous unit.
To overcome this problem, Rowan Fealy and John Sweeney of
the Department of Geography at NUI, Maynooth have used statistical
downscaling to make climate predictions for a 10 x 10 km grid
over Ireland. The resulting data indicates what to expect
of the Irish climate during this century. These data results
are ideally suited to use with crop simulation models to predict
changes in crop yield.
Crop models have been used to predict future yields of barley,
maize, potato, soybean and grass. The selected crops provide
a good indication of the range of changes that can be expected
to influence agricultural production in the future. Results
for the differing crops vary across the country and reflect
the predicted pattern of climate that can be expected. Looking
at some established crops, barley is predicted to show improved
yields in the future despite the fact that there may be some
limitations of yield due to reduced summer rainfall. This
may be offset by the elevated concentration of atmospheric
CO2 (the so called ‘CO2 fertilisation’ effect).
The expected fall in summer and autumn rainfall, particularly
to the north of Dublin is predicted to cause significant yield
decreases for potato crops unless more irrigation is introduced.
The impact on seed potato production in the North West will
probably be less. The data indicates that irrigation requirements
of potatoes by the middle of the century could be substantial
and unless water stress is managed any potential yield increase
from elevated CO2 will be lost. The cost and availability
of water, particularly on the east coast is going to be a
significant issue for both urban and rural dwellers in the
coming years and will perhaps dictate which agricultural enterprises
are viable.
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