Rapid assessment of the impacts of climate change (RAICC): An integrated approach to understanding climate change in the Halton region of Ontario, Canada

Climate change has resulted, and will result, in a set of diverse and regionally-specific impacts on natural ecosystems and human societies. Canadian municipalities can play an important and vital role in addressing climate change especially in mitigating or adapting to existing or future climate change impacts. Municipalities need direction on the priority that should be given to climate change in their community. This study focuses on developing an integrated approach to setting this priority called the Rapid Assessment of the Impacts of Climate Change (RAICC), and is applied to the Regional Municipality of Halton, Ontario, Canada. The five step RAICC approach includes building a history of climate extremes, selecting a model for climate futures, building a future of climate extremes, linking climate indices to adaptation thresholds and then conducting a relative risk assessment of the impacts. Results from applying the approach to the Halton Region show that climate change is an important issue to Halton, and its importance will increase over the 21 st century. Climate observations show increases in temperature and decreases in precipitation over the past 28 years. Future climate modelling projects continued increases in temperatures for Halton Region on average 3.8°C by the year 2100, mostly in minimum temperatures. Also, the climate models show that changes to precipitation levels eventually level off by mid-century with a slight increase by the year 2100. A literature review was conducted in order to identify climate change adaptation thresholds (sensitivities triggered at certain climate thresholds above which result in significant changes that may require some form of human interventionist adaptation) for ten economic and ecological sectors of Halton Region. The changes in risks/opportunities were assessed together with the model uncertainty to provide a relative risk assessment on the impacts of climate change at Halton Region. This study concludes that the built environment, agriculture and tourism are those eco-sectors in Halton Region requiring priority focus, more in-depth study and subsequent action.