Research

Part 1
There’s been a series of new terms recently added to the agricultural lexicon: climate change, global warming, carbon sequestration, bioproducts, Kyoto protocol, greenhouse gases (GHGs), carbon sinks, etc. The following article, the first in a series on this issue, will define some critical terms and place them within an agricultural context. As this series proceeds, we will examine both the opportunities and the challenges Canada’s agriculture sector will face should the country proceed with current plans to implement the Kyoto Protocol.

The terms ‘global warming’ and ‘climate change’ are sometimes used interchangeably. However, global warming is the recorded overall rise of the earth’s average temperature. As a result of global warming, climate change occurs. Scientists predict more variability to our weather in the form of more severe storms, floods and droughts, but no one can accurately predict - either geographically or numerically - the extent of the events that will occur.

World governments have reacted to address the less than unanimous, but majority scientific consensus that global warming is a reality. In 1997, 160 industrialized countries agreed to overall lower their greenhouse gas (GHG) emissions by 5.2% below 1990 levels by 2008-2012. Canada agreed to a 6% decrease at this meeting in Kyoto, Japan. The Kyoto Protocol was born. The six GHGs covered under the protocol are three gases of natural sources: carbon dioxide (CO2), methane (CH4), and nitrous oxide (N20). Three other gases – hydrofluorocarbons (HFCs), perfluorcarbons (PFCs), and sulphurhexafluoride (SF6) are man-made. Each gas has a different ability to warm the atmosphere and is referred to as the global warming potential (GWP) of the gas. The GWP of each gas is compared to that of CO2 and can be expressed in terms of CO2 equivalence (CO2e). As indicated by the chart below, one molecule of N20 is equivalent to 310 molecules of carbon dioxide.

Canada’s GHG emissions have increased significantly since 1990, and the actual level of reduction needed to meet the terms made under the agreement is now 30%.

Canada’s federal government recently announced a draft plan on climate change that will provide the basis for a national strategy to address the issue. This strategy will affect all sectors including agriculture. The implementation of this strategy is expected to reduce Canada’s GHG emissions by 240 megatonnes.

Agriculture and Greenhouse Gases
Agriculture is responsible for 10% of the total GHG emissions for Canada (see Figure 1). However, if appropriate government measures are taken, agriculture can provide enough GHG reductions for Canada to reach 20% of its reduction target as laid out in the Kyoto Protocol.

Agriculture can help meet the target in two distinct ways:

1) Emission reductions of GHGs through the use of best management practices (BMPs).
2) Emission removals by carbon sequestration.

The unique situation for the agricultural sector results from the predominance of methane and nitrous oxide as the major GHG emissions, 41 and 56 per cent of all agricultural emissions respectively. This corresponds directly to livestock and fertilizer management. The sources are divided between agricultural soils (49.7%), enteric fermentation (i.e., ruminant livestock digestion – 28.4%), manure management (13.7%) and other (8.2%).

Figure 1 - Greenhouse Gas Emissions by Sector, 1998. (Source: Government of Canada Action Plan on Climate Change, 2000)

Another unique aspect for agriculture is its ability to sequester carbon dioxide from the atmosphere to the soil. The carbon cycle that agriculture manages is the base. In detail, carbon dioxide from the atmosphere is stored in plants through the process of photosynthesis. A portion of this plant matter is returned or left to the soil in the form of roots and residue. Between soil fauna and abiotic processes, these inputs are converted to soil organic matter. This removal of a GHG from the atmosphere by storing the GHG is called a sink.

In the next article in this series, these concepts will be explored further to illustrate the opportunities and challenges for the agricultural sector.

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