The Rural Voice, 1998-01, Page 18Guest Column
What do Canadian commitments on greenhouse gas
emissions mean for agriculture?
By Terry Daynard
The Canadian government
commitment to reduce net emissions
of greenhouse gases below 1990 levels
has major implications for Canadian
agriculture.
Agriculture is a contributing source
of man-made emissions of three
greenhouse gases, carbon dioxide,
methane and nitrous oxide. Carbon
dioxide comes from fossil fuel usage,
and losses in soil organic matter.
Methane comes from livestock manure
and ruminant animals. Nitrous oxide
comes from fertilizer usage, crops and
manure.
However, changing agricultural
practices mean that the sum of these
net emissions is declining. Canadian
agriculture will be a significant player
in national efforts to meet our inter-
national greenhouse gas obligations.
A study completed in 1994 by the
Working Group on Agriculture and
Greenhouse Gas Emissions of the
National Agricultural Environment
Committee found that the decrease is
occurring for a number of reasons.
These include: reduced acreages of
summer fallowing (less soil is left bare
during the growing season), reduced
soil tillage with resultant increases in
soil organic matter (soil organic matter
is a "sink" for carbon dioxide), less
fossil fuel usage for field operations,
increased acreage of perennial forage
crops, increased efficiency of fertilizer
usage and livestock feeding, increased
photosynthetic rates, and increased
usage of renewable fuels such as
ethanol. These calculations are
currently being reworked, using 1996
census information and recent research
results. However, the overall pattern
is not expected to differ when an
updated report is released in 1998.
The
International
Panel on
Climate Change
(IPCC) of the
United Nations
Environmental
Program has
concluded that
expected global
warming should
have an overall
beneficial effect
on agriculture in
temperate and
northern
latitudes.
Within Canada, the benefits might be
greatest in the westem and northern
prairies. (The IPCC expects an overall
neutral effect on total world food
production.)
Warmer temperatures will mean
longer Canadian growing seasons, and
more opportunity in both western and
eastem Canada to plant autumn -seeded
grain crops, which are higher yielding
than the spring -seeded grain crops now
usually grown. However, there could
be an increased risk of drought, and
greater need for irrigation. Higher at-
mospheric carbon dioxide levels should
mean higher crop photosynthetic rates
(higher yields) and improved water use
efficiency by growing plants.
Plant breeding can be expected to
Agriculture
isa
contributing
source of
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14 THE RURAL VOICE
counter any increased risk caused by
warmer -season diseases and insect
pests. Indeed, the accelerating pace of
change in Canadian agricultural
technology means that farm crops and
cropping practices, food processing,
and livestock feeding practices will
almost certainly be far different in the
coming decades — with or without
global warming.
Many environmentalists and some
Canadian government agencies have
said that the biggest threat from global
warming will come from increased
climatic variability (more storms and
other extreme events), rather than
average temperature increases per se.
However, these statements are not
supported by the IPCC which has
concluded that "there are inadequate
data to determine whether consistent
changes in climate variability or
whether extremes have occurred over
the 20th century."
The IPCC says that climate could
become somewhat more variable in
some regions, and less so in others,
with the specifics being hard to
predict. (IPCC reports can be found
on the World Wide Web at
www.ipcc.ch) Canadian farmers
already deal with large year-to-year
variations in growing conditions.
There seems to be limited scientific
rationale for assuming that the
Canadian agricultural growing season
will become more variable — or less.
Though expected overall effects of
climatic warming on Canadian
agriculture may not be negative,
Canadian farmers do have global
responsibilities. There are good
reasons to reduce net greenhouse gas
emissions. There are ways to reduce
net emissions in Canadian agriculture
in a manner which have other
desirable environmental and economic
benefits. It makes sense to continue to
enhance these opportunities.0
Terry Daynard is executive vice-president
of the Ontario Corn Producers'
Association, chair of the Working Group
on Agriculture and Greenhouse Gas
Emissions of the National Agriculture
Environment Committee, and former
professor of crop science at the University
of Guelph. He and his wife manage a
cash -crop farm near Guelph, Ontario.