Barrie Creeks, Lovers Creek, and Hewitt's Creek Subwatershed Plan

The Barrie Creeks, Lovers Creek and Hewitt’s Creek Subwatershed Plan
To obtain more accurate projections for parameters such as seasonal and annual temperature
and precipitation, an ensemble of climate models are typically run together. The report
“Adapting to Climate Change in Ontario: Towards the Design and Implementation of a Strategy
and Action Plan” was released by the Expert Panel on Climate Change in November 2009
(EPCCA, 2009). The study included a review of climate change model projections for Ontario,
completed by Environment Canada (CCCSN, 2009). The projections were based on a
combination of 24 models and divides Ontario into 63 grid cells, one of which covers the Lake
Simcoe watershed. Three scenarios were produced based on future amount of greenhouse gas
(GHG) emissions (Low, Medium and High).
Table 2-11 lists the projected change in average annual and seasonal temperatures, comparing
1961-1990 to the 2050s. From it we can see under high GHG emissions there is a projected
increase in temperature of 3% for the area. All seasons are expected to see at least a 2.2%
temperature increase; however the most significant increase is seen during the winter, where
there is a projected increase of 2.5 -3.4% based on Low to High GHG emissions.
Table 2-10: Summary of projected change in average annual temperature (°C) in the 2050s
compared with 1961-1990 (CCCSN, 2009).
Projected change in air temperature ( o C)
GHG emmision scenario
Season Low Medium High
Annual 2.3 2.7 3.0
Winter 2.5 3.0 3.4
Spring 2.2 2.5 2.8
Summer 2.2 2.6 2.9
Autumn 2.3 2.6 2.8
Table 2-12 lists the projected change in average annual and seasonal temperatures, comparing
1961-1990 to 2050s.Under the high GHG emission scenario, annual precipitation is projected to
increase by 5.51%. All seasons are expected to increase by at least 3.06%, with the exception
of summer precipitation. As the amount of GHG emissions increase, there is only a slight
increase predicted for the Low and Medium emission scenarios, and a decrease in the amount
of precipitation of -0.62% under High GHG emission scenario.
Table 2-11: Summary of projected change in precipitation (%) in 2050s compared with 1961-1990
(CCCSN, 2009).
Projected change in precipitation (%)
GHG emmision scenario
Season Low Medium High
Annual 5.15 5.45 5.51
Winter 9.38 10.19 10.76
Spring 8.58 9.1 9.65
Summer 0.92 0.11 -0.62
Autumn 3.06 3.79 3.82
Despite the use of a combination of multiple models, it is important to note that there is still a
very high level of uncertainty associated with the projections. As scientists continue to
understand the smaller interactions (i.e. what role clouds play in climate change) and are able to
integrate them into the models, this uncertainty will decrease.
Chapter 2: Study Area: The Barrie Creeks, Lovers Creek and Hewitt’s Creek Subwatersheds 75