Changes

* “As for the temporal trends, significant warming trends are detected throughout the province of ON and the overall trend in annual mean temperature varies largely between 0.01 and 0.02 ∘C year–1. Increasing trends in annual rainfall (by 1 – 3 mm/year) and total precipitation (by 1 – 4 mm/year) are detected at the vast majority of gauged stations, but no significant trends in annual snowfall are identified at most of the stations.”<ref>Wang, Xiuquan, Guohe Huang, and Jinliang Liu. 2016. “Observed Regional Climatic Changes over Ontario, Canada, in Response to Global Warming.” Meteorological Applications 23 (1):140–49. https://doi.org/10.1002/met.1541.</ref>

* “As for the temporal trends, significant warming trends are detected throughout the province of ON and the overall trend in annual mean temperature varies largely between 0.01 and 0.02 ∘C year–1. Increasing trends in annual rainfall (by 1 – 3 mm/year) and total precipitation (by 1 – 4 mm/year) are detected at the vast majority of gauged stations, but no significant trends in annual snowfall are identified at most of the stations.”<ref>Wang, Xiuquan, Guohe Huang, and Jinliang Liu. 2016. “Observed Regional Climatic Changes over Ontario, Canada, in Response to Global Warming.” Meteorological Applications 23 (1):140–49. https://doi.org/10.1002/met.1541.</ref>

* “Extreme downpours are now happening 30 percent more often nationwide than in 1948. In other words, large rain or snowstorms that happened once every 12 months, on average, in the middle of the 20th century now happen every nine months. Moreover, the largest annual storms now produce 10 percent more precipitation, on average.”  Madsen et al 2012 a study in the US

* “Extreme downpours are now happening 30 percent more often nationwide than in 1948. In other words, large rain or snowstorms that happened once every 12 months, on average, in the middle of the 20th century now happen every nine months. Moreover, the largest annual storms now produce 10 percent more precipitation, on average.”  Madsen et al 2012 a study in the US

* “Extreme weather events including prolonged heat waves, torrential rainstorms, windstorms, and drought have increased throughout Ontario in recent years (Ontario, 2011). The frequency of very hot days (above 32°C) is expected to increase by 2.4-fold in Ontario by the late 21st century (Vavrus and Dorn 2009)”.  cited in Thunder Bay, 2015

* “Extreme weather events including prolonged heat waves, torrential rainstorms, windstorms, and drought have increased throughout Ontario in recent years (Ontario, 2011). The frequency of very hot days (above 32°C) is expected to increase by 2.4-fold in Ontario by the late 21st century <ref>Thunder Bay. 2015. “Climate-Ready City: City of Thunder Bay Climate Adaptation Strategy,” no. December:116.</ref>

* “Increases in the frequency and magnitude of extreme rainfall events have been documented in New York State (Fig. 1). These changes are among the largest seen within the United States (DeGaetano 2009). Climate change projections suggest that these increases will continue (Frumhoff et al. 2007).”  in Tryhorn 2010

* “Increases in the frequency and magnitude of extreme rainfall events have been documented in New York State. These changes are among the largest seen within the United States (DeGaetano 2009). Climate change projections suggest that these increases will continue <ref>Tryhorn, Lee. 2010. “Improving Policy for Stormwater Management: Implications for Climate Change Adaptation.” Weather, Climate, and Society 2 (2):113–26. https://doi.org/10.1175/2009WCAS1015.1.</ref>

===Projected===

===Projected===

*Increase in frequency and intensity of extreme precipitation events between now and 2100 (Larson et al 2011)

*Increase in frequency and intensity of extreme precipitation events between now and 2100 <ref>Larson, L, Nicholas Rajkovich, and Clair Leighton. 2011. “Green Building and Climate Resilience: Understanding Impacts and Preparing for Changing Conditions.” University of Michigan, 260. </ref>

* “The analysis indicates that there is likely to be an obvious warming trend with time over the entire province. The increase in average temperature is likely to be varying within [2.6, 2.7]8C in the 2030s, [4.0, 4.7]8C in the 2050s, and [5.9, 7.4]8C in the 2080s. Likewise, the annual total precipitation is projected to increase by [4.5, 7.1]% in the 2030s, [4.6, 10.2]% in the 2050s, and [3.2, 17.5]% in the 2080s. Furthermore, projections of rainfall intensity–duration–frequency (IDF) curves are developed to help understand the effects of global warming on extreme precipitation events. The results suggest that there is likely to be an overall increase in the intensity of rainfall storms. Finally, a data portal named Ontario Climate Change Data Portal (CCDP) is developed to ensure decision-makers and impact researchers have easy and intuitive access to the refined regional climate change scenarios.”  in Wang et al 2015

* “The analysis indicates that there is likely to be an obvious warming trend with time over the entire province. The increase in average temperature is likely to be varying within [2.6, 2.7]8C in the 2030s, [4.0, 4.7]8C in the 2050s, and [5.9, 7.4]8C in the 2080s. Likewise, the annual total precipitation is projected to increase by [4.5, 7.1]% in the 2030s, [4.6, 10.2]% in the 2050s, and [3.2, 17.5]% in the 2080s. Furthermore, projections of rainfall intensity–duration–frequency (IDF) curves are developed to help understand the effects of global warming on extreme precipitation events. The results suggest that there is likely to be an overall increase in the intensity of rainfall storms. Finally, a data portal named Ontario Climate Change Data Portal (CCDP) is developed to ensure decision-makers and impact researchers have easy and intuitive access to the refined regional climate change scenarios.”  in Wang et al 2015

* “Some researchers, however, have demonstrated that the volume (Kuchenbecker et al. 2010, in Germany; cited in Bendel et al. 2013), frequency (Bendel et al. 2013, in Germany; Fortier and Mailhot 2014, May and October in Canada) or mean annual duration (Fortier and Mailhot 2014,in Canada) of CSOs should increase in the future climate. Logically, these increases will cause water quality to deteriorate in urban rivers – impacts that could be more severe as a result of increased water temperature.”  St-Hilaire et al 2016

* “Some researchers, however, have demonstrated that the volume (Kuchenbecker et al. 2010, in Germany; cited in Bendel et al. 2013), frequency (Bendel et al. 2013, in Germany; Fortier and Mailhot 2014, May and October in Canada) or mean annual duration (Fortier and Mailhot 2014,in Canada) of CSOs should increase in the future climate. Logically, these increases will cause water quality to deteriorate in urban rivers – impacts that could be more severe as a result of increased water temperature.”  St-Hilaire et al 2016