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>

* Pyke et al 2011 – Boston scenario for with and without LID vs conventional

* Pyke et al 2011 – Boston scenario for with and without LID vs conventional

* “Burian (2006) assesses drainage infrastructure performance in response to increased precipitation intensity. The results show that upstream parts of urban drainage catchments in the United States may be resilient to precipitation effects of climate change because most development codes have required a minimum pipe size that has resulted in oversized drainage systems. Results also show downstream parts of urban catchments are more affected by in- creased precipitation intensity and thus more susceptible to the effects of flooding from climate change.”  cited in Zahmatkesh et al 2014

* “Burian (2006) assesses drainage infrastructure performance in response to increased precipitation intensity. The results show that upstream parts of urban drainage catchments in the United States may be resilient to precipitation effects of climate change because most development codes have required a minimum pipe size that has resulted in oversized drainage systems. Results also show downstream parts of urban catchments are more affected by in- creased precipitation intensity and thus more susceptible to the effects of flooding from climate change.”  cited in Zahmatkesh et al 2014

* Impacts of weather on buildings, roads, bridges, hydro-transmission lines, stormwater drainage, drinking water and water treatment services, natural gas and communication lines, range from softening of tarmac during summer heat waves and cracking of concrete during freeze-thaw cycles, to catastrophic flooding, road washouts, ice and windstorm damage. The frequency and intensity of all these small- and large-scale effects is changing and infrastructure of all kinds is in danger of becoming subject to conditions for which it was not designed. For example, this means that the environmental performance of some infrastructure, such as wastewater and stormwater infrastructure may become inadequate, which would have impacts on the water quality, water quantity and the ecosystem.  Ontario 2012 (Action Plan)

* Impacts of weather on buildings, roads, bridges, hydro-transmission lines, stormwater drainage, drinking water and water treatment services, natural gas and communication lines, range from softening of tarmac during summer heat waves and cracking of concrete during freeze-thaw cycles, to catastrophic flooding, road washouts, ice and windstorm damage. The frequency and intensity of all these small- and large-scale effects is changing and infrastructure of all kinds is in danger of becoming subject to conditions for which it was not designed. For example, this means that the environmental performance of some infrastructure, such as wastewater and stormwater infrastructure may become inadequate, which would have impacts on the water quality, water quantity and the ecosystem. <ref>Ontario, Government of. 2012. “CLIMATE READY Ontario’s Adaptation Strategy and Action Plan.” Ministry of the Environment, 124p.</ref>

* “Thus, in order to adapt to the increased winter precipitation expected with climate change, greenspace provision will need to be considered alongside increased storage. There is significant potential to utilize sustainable urban drainage (SUDS) techniques, such as creating swales, infiltration, detention and retention ponds in parks”  Gill et al 2007

* “Thus, in order to adapt to the increased winter precipitation expected with climate change, greenspace provision will need to be considered alongside increased storage. There is significant potential to utilize sustainable urban drainage (SUDS) techniques, such as creating [[swales]], [[infiltration]], detention and [[retention ponds]] in parks” <Ref>Gill, S E, J F Handley, a R Ennos, and S Pauleit. 2007. “Adapting Cities for Climate Change: The Role of the Green Infrastructure.” Built Environment 33 (1):115–33. https://doi.org/10.2148/benv.33.1.115.</ref>

* “CC effects were on average two orders of magnitude greater than LU impacts on mean daily stream T. LU change affected stream T primarily in headwater streams, on average up to 2.1°C over short durations, and projected CC affected stream T, on average 2.1 - 3.3°C by 2060.” <ref> Daraio and Bales 2014 – a modelling study that assesses the effects of land use vs climate change on urban stream temperatures </ref>

* “CC effects were on average two orders of magnitude greater than LU impacts on mean daily stream T. LU change affected stream T primarily in headwater streams, on average up to 2.1 °C over short durations, and projected CC affected stream T, on average 2.1 - 3.3 °C by 2060.” <ref> Daraio and Bales 2014 – a modelling study that assesses the effects of land use vs climate change on urban stream temperatures </ref>

*Higher temperatures, greater annual precipitation, larger precipitation events, increase in frequency of high flow events. Future climate scenarios predict a 40% increase in future TSS loading. Return periods for critical flows are reduced in future scenarios, while larger storms will be more frequent. Baseflow will decrease with potential impacts on rates of stream aggradation. Increased risk of erosion damages to infrastructure . Stream crossings may need to be larger. Erosion thresholds exceeded more frequently. Greater sediment loading in watercourses. Combines with higher peak flows and lower baseflow, altered sediment transport regimes could change the way our rivers form and adjust. Potential change in vegetation, habitat with increase of invasive species, drying wetlands, stress on fish species in warm and turbid waters.  Karen Hofbauer 2016 NCD 2016 Conference Presentation. Need to contact her in few months to obtain a draft of the study. Based in Hamilton – good local example of potential impacts of climate change to local streams and rivers.

*Higher temperatures, greater annual precipitation, larger precipitation events, increase in frequency of high flow events. Future climate scenarios predict a 40 % increase in future TSS loading. Return periods for critical flows are reduced in future scenarios, while larger storms will be more frequent. Baseflow will decrease with potential impacts on rates of stream aggradation. Increased risk of erosion damages to infrastructure . Stream crossings may need to be larger. Erosion thresholds exceeded more frequently. Greater sediment loading in watercourses. Combines with higher peak flows and lower baseflow, altered sediment transport regimes could change the way our rivers form and adjust. Potential change in vegetation, habitat with increase of invasive species, drying wetlands, stress on fish species in warm and turbid waters.<ref>Karen Hofbauer 2016 NCD 2016 Conference Presentation.</ref>

===Concerns with projections===

===Concerns with projections===

*Even if we significantly reduce GHGs, the impacts of climate change will continue.

*Even if we significantly reduce GHGs, the impacts of climate change will continue.  

*There is uncertainty in the models, confusing policy makers and practitioners

*There is uncertainty in the models, confusing policy makers and practitioners

*“The extent of the impact of climate change is not fully known, and there are limitations in understanding the Earth’s climatic variations over long spans of time (CSIRO 2007). Additionally the modelling of climate projections to a local level is still not yet precise. As expressed by the MOE (2011): “Climate change science and modeling currently is not at a level of detail suitable for stormwater management where knowledge of the intensity, duration, frequency of storms and their locations and timing is required. However the economic, health and environmental risks dictate a need to be proactive in the management of stormwater.” These uncertainties require a process for continuously assessing the adapted measures, as well as assessing the physical facilities or infrastructures affected by these adaptations.” <ref>Upadhyaya, Jyoti Kumari, Nihar Biswas, and Edwin Tam. 2014. “A Review of Infrastructure Challenges: Assessing Stormwater System Sustainability.” Canadian Journal of Civil Engineering 41 (6):483–92. https://doi.org/10.1139/cjce-2013-0430.</ref>

*“The extent of the impact of climate change is not fully known, and there are limitations in understanding the Earth’s climatic variations over long spans of time (CSIRO 2007). Additionally the modelling of climate projections to a local level is still not yet precise. As expressed by the MOE (2011): “Climate change science and modeling currently is not at a level of detail suitable for stormwater management where knowledge of the intensity, duration, frequency of storms and their locations and timing is required. However the economic, health and environmental risks dictate a need to be proactive in the management of stormwater.” These uncertainties require a process for continuously assessing the adapted measures, as well as assessing the physical facilities or infrastructures affected by these adaptations.” <ref>Upadhyaya, Jyoti Kumari, Nihar Biswas, and Edwin Tam. 2014. “A Review of Infrastructure Challenges: Assessing Stormwater System Sustainability.” Canadian Journal of Civil Engineering 41 (6):483–92. https://doi.org/10.1139/cjce-2013-0430.</ref>