Future Weather in Toronto and the GTA

Transcription

1 Future Weather in Toronto and the GTA Due to Climate Change Electrical Sector Meeting, Nov. 23 rd, 2011 Christopher Ll. Morgan, PhD Toronto Environment Office

2 Contents 2 Introduction (Why We Did What We Did) New Approach To Answer New Questions Modelled Results ( ) Confidence in Results Significance & Application of Results

3 Why We Did What We Did 3 Clear Direction from City Council re: policies and actions Climate Change Action Plan (2007) Ahead of the Storm (2008) To Prepare the City For the Future Needed Toronto & GTA Specific Weather & Climate Information But this is unavailable from Environment Canada Toronto Goes It Alone! With Help From Others! Advisors (EC, MOE, TRCA) + SENES + Hadley (UK) Builds on Existing Work!! (Combined Technologies) Global Climate Models (GCM) Regional Climate Models (RCM) Local Weather Models (WRF/FReSH)

4 New Approach.. 4 The approach was completely new and innovative when this project was conceived. The approach taken has been very successful (proved value of pilot approach). Approach subsequently adopted by the National Center for Atmospheric Research (NCAR), and by the MOE with U of T.

5 . To Answer New Questions 5 Included Influence of the Great Lakes, Niagara Escarpment and the Oak Ridges Moraine. Examined a 10 Year Period (not 30 Years) Wanted to obtain data and information concerning the future extremes-of-weather rather than the future means-of-climate.

6 Results: Changes in Precipitation 6 Snowfall & Rainfall Extreme DAILY Rainfall (>25mm/day) Less Snow & More Rain -- in Winter More Rain in July (80%) & August (50%) Fewer Rain Storms >25 mm in Winter Same Number of Storms in Summer BUT these = Much More Intense Storms!! Difference in Amount Pearson Airport: Change to Rainfall (mm) Snowfall (cm) Amount in mm Pearson Airport: Extreme DAILY Rainfall Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month 20 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month

7 Spatial Variation: Less Snow centimetres less in parts of Toronto 160 centimetres less on parts of the Oak Ridges Moraine Relatively Easy to Do This Based on Mean Values (Daily/Monthly/Annual etc)

8 Modelling Future Storms is Harder 8 Storm of August 19 th, 2005 a) Highest Rainfall is shown over Finch Avenue b) Captured by Modelling, but NOT by the TBRG Monitoring at Pearson

9 Results: Warmer Temperatures 9 Average annual temperatures increase by 4.4 o C Projected average winter temp. increases by 5.7 o C. Projected average summer temp. increases by 3.8 o C. The extreme daily minimum temperature - becomes less cold" by 13 o C. The extreme daily maximum temperature - "becomes warmer" by 7.6 o C.

10 Temperature Differences 10 Average annual temperatures increase by 4.4 o C BUT non-uniformly due to cooling influence of Lake Ontario, Simcoe etc

11 Results: Winds & Comfort 11 Wind speeds will be unchanged on average Maximum wind speeds will be reduced Humidex remains within 10% of present for most of year but increases by 40% in February, and by 20% in July through to September Wind Chill reduces by 50% - 5 months Chill free

12 Confidence in Results: Temperature 12 Compared with Monitored Means ( ) Toronto s Climate-Weather Model v.1= 8.70 o C EC s CRCM v = 6.69 o C Monitored Data from Pearson = 8.73 o C Compared with Other Models ( ) for GTA NB Compares High versus Low Resolution Models Our Delta 4.4 o C compares favourably with Low Res Models showing Deltas from -2.7 o C to 6.3 o C

13 Confidence in Extremes: 13 Compared means among models for Our GCM/RCM/WRF approach did well! Compared modelled means and extremes results versus monitored observations for Our model did well! Modeling temperature & heat waves always easier than modelling precipitation & storms especially regarding extremes (e.g. extremes of storm rainfall) - so confidence in results varies accordingly.

14 Application of Results 14 What the City wanted to obtain was data and information concerning the future extremes-of-weather rather than the future means-of-climate. Extremes are more significant for public operations and service provision regarding such basics as flood appropriate sewer and culvert pipe sizing, heat wave appropriate load-bearing resistance of road surface materials, and heat appropriate public services for the elderly and disadvantaged. I have not included my thoughts re significance for electricity but flooding, ice storms, heat waves etc seem relevant here?

15 15 Future Weather Toronto & GTA The End Questions and Answers Can Contact: