Changes

*Extreme precipitation events are likely to increase in magnitude and in frequency, particularly in the summer time when convective activity is highest in and surrounding York Region. The future trend of extreme precipitation intensity; however, is unclear. It is recommended that a conservative approach should be taken in planning and adapting for extreme precipitation events.

*Extreme precipitation events are likely to increase in magnitude and in frequency, particularly in the summer time when convective activity is highest in and surrounding York Region. The future trend of extreme precipitation intensity; however, is unclear. It is recommended that a conservative approach should be taken in planning and adapting for extreme precipitation events.

*The growing season in York Region is expected to lengthen by over 30 days by the 2050s. With this, the start date will shift earlier and the end date will shift later in the year. It is less certain, but more likely than not, that drier conditions will be present throughout the growing season in the 2050s as a result of no significant increase in precipitation over summer months and significant increases in temperatures.”<ref>OCC, GLISA, Clean Air Partnership. 2016. “Historical and Future Climate Trends in York Region.”</ref>

*The growing season in York Region is expected to lengthen by over 30 days by the 2050s. With this, the start date will shift earlier and the end date will shift later in the year. It is less certain, but more likely than not, that drier conditions will be present throughout the growing season in the 2050s as a result of no significant increase in precipitation over summer months and significant increases in temperatures.”<ref>OCC, GLISA, Clean Air Partnership. 2016. “Historical and Future Climate Trends in York Region.”</ref>

* “If [winter] precipitation falls as rain instead of snow, which may actually occur more frequently in temperate regions with climate change, phosphorus concentrations in winter have the potential to be equivalent to those observed in other seasons due to the ubiquitous impacts of runoff events.” “Another potential impact of climate change on summer nutrient conditions that has been discussed in the literature is an increase of summer soluble reactive phosphorus (SRP) concentrations in creeks during low flow conditions due to temperature-dependent release from riverine sediments.”<Ref>Long, Daniel L., and Randel L. Dymond. 2014. “Thermal Pollution Mitigation in Cold Water Stream Watersheds Using Bioretention.” Journal of the American Water Resources Association 50 (4):977–87. https://doi.org/10.1111/jawr.12152.</ref>

* “If winter precipitation falls as rain instead of snow, which may actually occur more frequently in temperate regions with climate change, phosphorus concentrations in winter have the potential to be equivalent to those observed in other seasons due to the ubiquitous impacts of runoff events.” “Another potential impact of climate change on summer nutrient conditions that has been discussed in the literature is an increase of summer soluble reactive phosphorus (SRP) concentrations in creeks during low flow conditions due to temperature-dependent release from riverine sediments.”<Ref>Long, Daniel L., and Randel L. Dymond. 2014. “Thermal Pollution Mitigation in Cold Water Stream Watersheds Using Bioretention.” Journal of the American Water Resources Association 50 (4):977–87. https://doi.org/10.1111/jawr.12152.</ref>

* “Dominguez et al. (2012) found increases in the intensity of 20- and 50-year return period winter precipitation events over the western United States, while over Canada, Mailhot et al. (2012) showed that the intensity of annual maxima precipitation would increase, with the largest increases for Ontario, the Prairies and Southern Quebec.”<ref>Guinard, Karine, Alain Mailhot, and Daniel Caya. 2015. “Projected Changes in Characteristics of Precipitation Spatial Structures over North America.” International Journal of Climatology 35 (4):596–612. https://doi.org/10.1002/joc.4006.</ref>

* “Dominguez et al. (2012) found increases in the intensity of 20- and 50-year return period winter precipitation events over the western United States, while over Canada, Mailhot et al. (2012) showed that the intensity of annual maxima precipitation would increase, with the largest increases for Ontario, the Prairies and Southern Quebec.”<ref>Guinard, Karine, Alain Mailhot, and Daniel Caya. 2015. “Projected Changes in Characteristics of Precipitation Spatial Structures over North America.” International Journal of Climatology 35 (4):596–612. https://doi.org/10.1002/joc.4006.</ref>

* “The hydrological response to climate change was investigated through stormwater runoff volume and peak flow, while the water quality responses were investigated through the event mean value (EMV) of five parameters: turbidity, conductivity, water temperature, dissolved oxygen (DO) and pH. First flush (FF) effects were also noted. Under future climate scenarios, the EMVs of turbidity increased in all storms except for three events of short duration. The EMVs of conductivity were found to decline in small and frequent storms (return period <5 years); but conductivity EMVs were observed to increase in intensive events (return period ½5 years). In general, an increasing EMV was observed for water temperature, whereas a decreasing trend was found for DO EMV. No clear trend was found in the EMV of pH. In addition, projected future climate scenarios do not produce a stronger FF effect on dissolved solids and suspended solids compared to that produced by the current climate scenario.”<ref>He, Jianxun, Caterina Valeo, Angus Chu, and Norman F. Neumann. 2011. “Stormwater Quantity and Quality Response to Climate Change Using Artificial Neural Networks.” Hydrological Processes 25 (8):1298–1312. https://doi.org/10.1002/hyp.7904.</ref>

* “The hydrological response to climate change was investigated through stormwater runoff volume and peak flow, while the water quality responses were investigated through the event mean value (EMV) of five parameters: turbidity, conductivity, water temperature, dissolved oxygen (DO) and pH. First flush (FF) effects were also noted. Under future climate scenarios, the EMVs of turbidity increased in all storms except for three events of short duration. The EMVs of conductivity were found to decline in small and frequent storms (return period <5 years); but conductivity EMVs were observed to increase in intensive events (return period ½5 years). In general, an increasing EMV was observed for water temperature, whereas a decreasing trend was found for DO EMV. No clear trend was found in the EMV of pH. In addition, projected future climate scenarios do not produce a stronger FF effect on dissolved solids and suspended solids compared to that produced by the current climate scenario.”<ref>He, Jianxun, Caterina Valeo, Angus Chu, and Norman F. Neumann. 2011. “Stormwater Quantity and Quality Response to Climate Change Using Artificial Neural Networks.” Hydrological Processes 25 (8):1298–1312. https://doi.org/10.1002/hyp.7904.</ref>