Climate scenarios for agriculture
Agricultural production is highly dependent on weather and climate. Without adequate rainfall and appropriate temperatures, crops fail and pastures become barren. Interestingly, the opposite is also true: weather and climate are influenced by agricultural practices. By managing croplands and pastures farmers influence a series of physical, chemical and biological interactions between the Earth's surface and the atmosphere that can affect air temperature and precipitation in many ways.
It is important to understand that there is still a lot of uncertainty on the impact of climate change to agriculture. These potential impacts are not clear and depend heavily on assumptions that are developed from the use of models to make projections.
Also, the effectiveness of future adaptations will be a key factor.
That means there may be some surprises along the way.
Global climate models
Scientific projections about the future of our climate are developed by running global climate models that are based on scenarios that represent a range of possible future conditions. This includes greenhouse gas (GHG) concentrations in the atmosphere, population size, socio-economic development and technological changes.
These projections are heavily dependent on assumptions about future conditions. However, there is growing agreement within the scientific community that our future climate will be warmer with more extreme climate and weather events.
The climate scenarios mean global temperatures are likely to increase by 0.2°C per decade for the next two decades.
There is considerable evidence and data to suggest that the climate is already changing.
- Over the past century, the global mean surface temperature has increased by 0.6°C (± 0.2°C).
- The 1990s was the warmest decade of the past 1,000 years.
- Sea-ice cover has decreased.
- Shifts in species distributions have been observed.
- The global average sea level has increased.
- The number of heavy precipitation events has increased at northern latitudes and the frequency and severity of drought has also increased.
In addition, continental precipitation has increased by 5 to 10% over the 20th century in the northern hemisphere and has declined in parts of the Mediterranean and Africa.
There are also data to suggest that between 1950 and 2000, the daily surface temperature has decreased over land. Night-time minimum temperatures have also been increasing at twice the rate of daytime maximum temperatures.
There have been more frequent hot days and fewer cold or frost days over the past several decades.
Impact of climate change on Canadian agriculture
So how will climate change impact Canada and Canadian agriculture?
Numerous studies of the impact of climate change suggest that most regions of Canada are projected to warm during the next 60 years.
A changing climate can have both positive and negative impacts on agriculture. These changes can impact a number of different levels of the sector ranging from individual plants and animals, right up to entire global networks.
This warming may provide opportunities for agriculture in certain regions with an expansion of the growing season to go along with milder and shorter winters. This could increase productivity and allow the use of new and potentially more profitable crops.
For a high-latitude country like Canada, the warming is expected to be more pronounced than the global average. Northern regions and the southern and central Prairies will see more warming than other regions. Most regions will likely be warmer with longer frost-free seasons and increased evaporation and plant transpiration from the surface into the atmosphere.
These warmer temperatures would also benefit livestock production in the form of lower feed requirements, increased survival rates of the young and lower energy costs.
Climate change could improve soil quality by enhancing carbon sequestration and reducing the emissions of greenhouse gases by changes to land-use from annual crop production to perennial crops and grazing lands.
Using information produced by the Canadian Centre for Climate Modelling and Analysis global circulation model for the three Prairie Provinces under two conditions, current climate and future climate, Agriculture and Agri-Food Canada (AAFC) scientists predicted in 2004 that under a future climate, on average, high temperatures would increase by 2ºC to 3ºC and low temperatures increase by about 3ºC.
When compared to the current climate, the model predicted that precipitation was to increase by 3 to 7%.
The results suggested that Alberta would benefit the most from increased summer and winter precipitation. However, eastern Saskatchewan and Manitoba would experience little change or smaller increases. Since there is a growing-season moisture deficit in much of the Prairie region, even slight declines in the availability of moisture could significantly harm crop production.
However, one of the concerns is that climate change could have significant negative impacts including the increased intensity and frequency of droughts and violent storms.
As the frequency of events like droughts increases under climate change, crop yields would decrease. This would increase the vulnerability of producers to climate change, particularly in semi-arid regions of Canada.
Extreme events like the 2001 and 2002 droughts and floods of 2010 and 2011 can have a devastating impact on crop yields where yields could be reduced by as much as 50% of the average yields during normal or more suitable growing conditions.
Warmer summers could also cause problems for livestock producers related to heat-wave deaths. This is especially true in poultry operations. Other impacts could be reduced milk production and reduced reproduction in the dairy industry, as well as, reduced weight gain in beef cattle.
In addition, droughts and floods could reduce pasture availability and the production of forage, forcing producers to find alternative feed sources or reduce their herd size.
There are several possible effects climate change could also have on crop pests and disease. These would include increased weed growth due to higher levels of atmospheric Carbon Dioxide (CO2) and an increased prevalence of pests and pathogens in livestock and crops. The increased range, frequency and severity of insect and disease infestations are also potential impacts.
While these changes will not have large effects on greenhouse gas (GHG) emissions from crop production systems; they could cause an increase in energy use associated with the manufacture, transportation and application of pesticides.
Reducing agricultural emissions
Greenhouse gas (GHG) emissions are a natural part of the carbon and nitrogen cycles. What this means is that a certain level of emissions from any biological system is inevitable. There is no way that all methane (CH4) emissions from ruminant animals can be totally eliminated or that we can avoid nitrous oxide (N2O) emissions from decomposing crop residues.
Similarly, emissions of N2O and CH4 from livestock manure cannot be avoided.
However, there are some GHG emissions from crop and livestock production that are avoidable. These emissions represent leakages or inefficiencies in the system, both of which have environmental and economic consequences.
Emissions of N2O imply the inefficient use of nitrogen fertilizer. Emissions of CH4 from ruminant livestock indicate that the feed is not being efficiently converted to milk or meat products.
A great deal of research has been done that shows that plant and animal production systems can reduce GHG emissions and offer positive economic benefits.
Some examples of this include using inputs, such as fertilizers and machinery, more efficiently and adopting management practices that increase the amount of carbon stored in soils.
Using some of the biomass produced on agricultural land to produce bio-energy can help partly replace fossil fuels and using agricultural wastes to generate energy are additional examples of ways to reduce GHG emissions.
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