Long Term Climate Change - Short Term Extreme Rainfall Impacts - What Muzzled Scientists Can't Say


Previous posts have summarized trends in extreme rainfall for 565 climate stations across Canada. Its clear that while temperatures are up (global warming), climate change impacts are not affecting storm intensity.

Tables and maps have shown the trend direction (increasing or decreasing) and the strength of the trend (statistical significance). The complete list includes "out of service" stations and those with short periods of record, meaning their data are not as relevant to recent climate change trends. 
To focus on recent trends and more reliable long term records, the table below screens Environment Canada's stations to show only those with more than 45 years of record, and those whose last record is more recent than 2005. Only 26 stations meet this quality screening for long term, recent data sets.

Findings:

Short term extreme weather trends in western Canada show no statistically significant increase or decrease, meaning trends are minor / mild. Increases (shown as light red shading) are more prevalent than decreases (light green shading). Decreases have been observed over short durations (e.g., Calgary 5 and 10 minutes) and longer durations (e.g., Vancouver 6, 12 and 24 hour periods).

In Ontario, decreases in rainfall intensity are slightly more prevalent than increases. Statistically significant decreasing trends in rainfall extremes were observed in southern Ontario at two stations: Windsor Airport and Toronto City (aka 'Bloor Street'), shown with dark green shading. These decreases were for 7 statistics covering both short and long durations (10 minutes to 24 hours). Statistically significant increases were observed in eastern and northern Ontario for two statistics: Thunder Bay 30 minute duration, and Ottawa Airport 24 hour duration.
In the Maritimes and Newfoundland, increases are more prevalent than decreases. Statistically significant increases were observed in Moncton, New Brunswick, Shearwater Nova Scotia, and Gander, Newfoundland.

Climate Station
Province / Region		 Station ID
Engineering Climate Datasets
Annual Maximum Rainfall
Trend and Significance
Length
of
Record (Years)
Most

Recent

Year
5 min 10 min  15 min 30 min
1
hr
2
hr
6
hr
 12 hr 24 hr
British Columbia
Victoria Intl A BC        1018621 4 4 4 4 4 4 4 4 4 46 2013
Mission West Abbey BC        1105192 4 4 4 2 2 2 4 4 4 48 2010
Vancouver Intl A BC        1108395 4 4 4 4 4 4 2 2 2 59 2013


Alberta
Edmonton Int'L A AB        3012205 4 2 2 2 4 4 2 2 4 46 2011
Red Deer A AB        3025480 4 4 4 4 4 4 4 4 4 47 2012
Calgary Int'L A AB        3031093 2 2 4 4 4 4 4 4 4 56 2009


Saskatchewan
Estevan A SK        4012400 4 4 4 4 4 2 4 2 4 48 2011
Kindersley A SK        4043900 4 4 4 4 4 4 4 4 4 47 2013


Ontario
Ear Falls (Aut) ON        6012199 4 4 4 4 2 2 4 4 4 49 2006
Geraldton A ON        6042716 4 4 4 4 4 4 4 4 4 48 2006
Thunder Bay Cs ON        6048268 4 4 4 5 4 4 4 4 4 47 2006
Timmins Victor Power A ON        6078285 4 4 4 4 4 4 2 2 2 47 2006
Kingston Pumping Station ON        6104175 4 4 2 2 2 2 2 2 2 63 2007
Ottawa Cda Rcs ON        6105978 2 2 2 2 2 2 4 4 5 50 2007
St Thomas Wpcp ON        6137362 4 2 2 2 4 2 4 4 4 75 2007
Windsor A ON        6139525 2 1 2 2 2 1 1 1 2 60 2007
London Cs ON        6144478 4 4 4 4 2 2 2 2 2 57 2007
Toronto City ON        6158355 2 2 2 2 2 2 1 1 1 59 2007
Toronto Intl A ON        6158731 2 4 4 4 4 4 2 2 2 60 2013


Maritimes / Newfoundland
Charlo Auto NB        8100885 4 4 4 4 4 4 4 4 4 51 2013
Moncton Intl A NB        8103201 4 4 4 4 4 4 4 5 5 64 2013
Sable Island NS        8204700 4 4 4 4 4 4 4 4 2 50 2012
Shearwater Auto NS        8205091 4 4 4 5 4 4 4 4 4 53 2009
Sydney Cs NS        8205702 4 4 4 4 4 4 4 2 4 50 2013
Gander Airport Cs NL        8401705 4 2 2 4 4 4 5 5 5 65 2009
Goose A NL        8501900 4 4 4 4 4 4 4 2 2 50 2013

****
Sensitivity analysis on the screening criteria do not change the overall trends. We looked at period of record greater than 38 years, instead of 45 years, and this doubled the number of stations. Highlights:
  • The Ottawa International Airport station was added and had a statistically significant decrease in short term rainfall intensity (10 minutes, 15 minutes, 1 hour) - this is consistent with Ottawa CDA which had decreasing non-significant trends for 5 minute to 2 hour durations.
  • In the northern Ontario, Sault St. Marie Airport was added with a statistically significant increase over a one hour duration, just like Thunder Bay.
  • Statistically significant increases in rainfall over long durations (12-24 hours) were added in British Columbia (Tofino Airport, Blue River Airport).
  • A statistically significant increase was added at Fredericton CDA (5 minute duration).
Environment Canada's recent article on extreme rain trends published in Atmosphere-Ocean confirms there are no overall trends in rain intensity, and there are some regional minor increases and decreases - click for abstract.

Severe Storm Trends Canada - Rainfall Intensity Decreasing and Increasing - No Significant Climate Change

Legend for extreme rainfall trends.
The follow maps are extracted from the CityFloodMap.Com's interactive map of Environment Canada rainfall trends data.  The maps illustrate any climate change trends in short term extreme storm events. The full interactive map can be accessed at this link.

Maps show extreme rainfall trends over 5 minute durations that influence flooding in urban areas and small, 'flashy' catchments (e.g., small rural watersheds, or steep catchments that respond quickly to high intensity storm events). Tablular summaries of trends over longer durations up to 24 hours are included in another post.

Across Canada, 16 climate stations have observed statistically significant decreases in short term rain intensity, while 15 stations have observed statistically significant decreases.  Over 90% of Environment Canada's trends data shows no significant trend, or records are insufficient to determine trends.

British Columbia and Southern Alberta Extreme Rainfall Trends - Click to Enlarge

Southern Saskatchewan and Manitoba Extreme Rainfall Trends - Click to Enlarge
Northern Ontario Extreme Rainfall Trends - Click to Enlarge
Southern Ontario and Quebec Extreme Rainfall Trends - Click to Enlarge
Toronto, Hamilton, Niagara, Kitchener-Waterloo Extreme Rainfall Trends - Click to Enlarge

Maritimes and Eastern Quebec Extreme Rainfall Trends - Click to Enlarge
Newfoundland and Southern Labrador Extreme Rainfall Trends - Click to Enlarge
***

Extreme rainfall trends in Canada (Environment Canada Engineering Climate Datasets):

Static Maps: http://www.cityfloodmap.com/2015/12/severe-storm-trends-canada-rainfall.html

Interactive Map: http://www.cityfloodmap.com/2015/12/canadian-extreme-rainfall-map-climate.html

Table Summaries: http://www.cityfloodmap.com/2015/12/canadian-extreme-rainfall-summary-by.html

Chart and Table: http://www.cityfloodmap.com/2015/12/top-weather-story-in-canada-2015-less.html

 Long-term Station Table: http://www.cityfloodmap.com/2015/12/long-term-climate-change-short-term.html

Environment Canada Denies Changes: http://www.cityfloodmap.com/2015/10/bogus-statements-on-storms-in-cbcnewsca.html

Contradicting Insurance Industry Claims: http://www.cityfloodmap.com/2015/12/trends-in-canadian-shortduration.html




British Columbia - Extreme Short Duration Rainfall Trends

Vintage Rain Chart
The following table presents short term rainfall trends for BC climate stations. The significance of trends is shown as well as the trend direction - only a few percentage of stations have a significant trend that cannot be explained by random, minor variations. 'Decreasing' means less severe annual maximum rainfall amounts observed over the specified duration. Trends are from Environment Canada's Engineering Climate Dataset v2.3 (idf_v2-3_2014_12_21_trends.txt, in IDF_Additional_Additionnel_v2.30.zip, downloaded through ftp://ftp.tor.ec.gc.ca/Pub/Engineering_Climate_Dataset/IDF/).

 British Columbia Extreme Rainfall Trends

Climate Station Name
Pr.
Extreme Rainfall Trend

Decreasing / Significant

Decreasing / Not Significant

No Data

Increasing / Not Significant

Increasing / Significant
5 min
     10 min
             15 min
                30 min
1 hr
          2 hr
6  hr
                12 hr
24 hr
Lake Cowichan
BC  
3
3
3
3
2
4
2
2
2
Jordan River Diversion
BC  
3
3
3
3
2
2
4
4
4
Jordan River Generating
BC  
3
3
3
3
4
4
4
4
4
North Cowichan
BC  
3
3
3
3
4
4
4
4
2
Port Renfrew
BC  
3
3
3
3
3
4
4
2
2
Saanich Camosun College
BC  
3
3
3
3
4
4
4
4
4
Saturna Capmon
BC  
2
2
2
2
2
2
4
5
4
Victoria Gonzales Hts
BC  
4
4
4
4
5
5
4
4
4
Victoria Intl A
BC  
4
4
4
4
4
4
4
4
4
Victoria Marine
BC  
4
4
4
4
4
4
4
5
4
Victoria U Vic
BC  
3
4
4
4
4
4
4
4
4
Campbell River A
BC  
4
4
4
4
4
2
2
4
2
Campbell River Stp
BC  
2
2
2
2
2
2
2
4
2
Comox A
BC  
4
2
4
2
4
4
4
4
4
Courtenay Puntledge Bchp
BC  
3
3
3
3
5
5
5
5
4
Nanaimo A
BC  
5
5
4
4
2
2
1
1
1
Nanaimo City Yard
BC  
4
2
4
4
4
4
4
2
2
Parksville South
BC  
3
3
3
3
4
2
2
2
3
Nanaimo Departure Bay
BC  
3
3
3
3
4
4
4
4
4
Port Hardy A
BC  
4
4
4
4
5
4
2
1
2
Strathcona Dam
BC  
3
3
3
3
4
4
4
2
4
Amphitrite Point
BC  
2
4
4
5
4
4
4
5
4
Carnation Creek Cdf
BC  
3
3
3
3
4
4
4
4
4
Estevan Point
BC  
3
3
3
3
3
2
2
3
2
Port Alberni A
BC  
4
4
4
4
4
4
5
5
4
Tofino A
BC  
4
4
4
2
4
4
4
5
4
Clowhom Falls
BC  
3
3
3
3
4
4
4
4
4
Daisy Lake Dam
BC  
3
3
3
3
4
2
2
2
4
Gibsons
BC  
3
3
3
3
4
4
4
4
4
Merry Island Lightstation
BC  
3
3
3
3
4
2
2
2
2
Port Mellon
BC  
3
3
3
4
3
4
5
4
4
Powell River A
BC  
1
2
2
1
2
2
2
2
2
Squamish Aut0
BC  
3
3
2
2
2
2
4
4
4
Whistler
BC  
4
2
2
2
4
4
4
4
4
Langara
BC  
1
4
4
4
4
4
2
2
2
Moresby Island Mitchell Inlet
BC  
2
2
2
2
2
2
2
2
2
Sandspit A
BC  
4
4
4
4
2
2
2
2
2
Bella Coola A
BC  
4
5
5
5
5
5
4
4
2
Bella Coola Bc Hydro
BC  
4
2
2
1
2
2
2
2
2
Kitimat
BC  
3
3
3
3
4
4
4
4
5
Prince Rupert A
BC  
2
2
2
4
4
4
4
4
4
Stewart A
BC  
2
4
4
4
4
4
4
2
2
Terrace A
BC  
4
4
4
4
2
2
4
4
4
Terrace Pcc
BC  
4
4
4
4
4
4
4
4
4
Quick
BC  
3
2
2
3
4
2
2
2
2
Smithers A
BC  
4
4
4
4
4
4
2
2
2
Lajoie Dam
BC  
3
3
3
3
2
2
2
2
2
Pemberton Bcfs
BC  
3
3
3
3
5
5
5
5
5
Southbank
BC  
3
4
2
3
2
2
4
2
2
Burns Lake
BC  
4
4
2
4
4
4
2
2
2
Fort St James
BC  
3
3
3
3
4
4
4
4
4
Fort St James A
BC  
4
4
4
4
2
2
4
4
4
Horsefly Bcfs
BC  
3
3
3
3
5
5
4
4
2
Kersley
BC  
3
3
3
3
2
2
2
2
2
Mcbride Elder Creek
BC  
3
3
3
3
4
4
4
4
4
Mcbride North
BC  
3
3
3
3
4
4
5
5
5
Prince George A
BC  
2
2
4
4
4
2
2
2
2
Williams Lake A
BC  
2
2
3
4
3
3
3
3
2
Abbotsford A
BC  
4
4
4
4
4
4
2
4
2
Agassiz Cs
BC  
4
4
4
4
4
4
4
4
4
Alouette Lake
BC  
3
3
3
3
4
4
4
4
4
Buntzen Lake
BC  
3
3
3
3
4
4
4
4
4
Chilliwack Microwave
BC  
3
3
3
3
1
1
2
2
1
Coquitlam Lake
BC  
3
3
3
3
2
5
4
2
2
Haney Microwave
BC  
3
3
3
3
1
1
2
2
2
Haney Ubc Rf Admin
BC  
3
3
3
3
4
2
2
2
2
Huntingdon Vye Road
BC  
3
3
3
3
2
2
4
4
4
Ladner Bchpa
BC  
3
3
3
3
4
4
2
2
1
Langley Lochiel
BC  
3
3
3
3
2
2
4
2
2
Mission West Abbey
BC  
4
4
4
2
2
2
4
4
4
N Vancouver Lynn Creek
BC  
2
4
2
4
4
4
4
4
2
Pitt Polder
BC  
4
4
4
4
4
4
2
2
2
Port Coquitlam City Yard
BC  
2
2
2
2
4
4
2
2
2
Port Moody Glenayre
BC  
3
3
3
3
4
4
2
2
2
Surrey Kwantlen Park
BC  
4
4
4
4
4
4
4
4
2
Surrey Municipal Hall
BC  
3
3
2
2
4
4
2
2
2
Vancouver Harbour Cs
BC  
4
4
4
4
4
4
2
2
2
Vancouver Intl A
BC  
4
4
4
4
4
4
2
2
2
Vancouver Kitsilano
BC  
4
2
2
2
2
2
2
4
2
Vancouver Ubc
BC  
4
2
2
2
2
2
2
2
2
White Rock Stp
BC  
4
4
4
4
4
4
4
4
4
Pitt Meadows Stp
BC  
3
3
3
3
2
2
2
2
4
Burnaby Mtn Bchpa
BC  
3
3
3
3
4
4
4
2
4
N Vanc Sonora Dr
BC  
2
1
2
2
2
2
2
4
4
Hells Gate
BC  
3
3
3
3
1
1
2
2
2
Hope A
BC  
4
4
4
4
4
4
4
4
4
Lillooet Seton Bchpa
BC  
3
3
3
3
4
4
4
4
4
Lytton
BC  
3
4
4
4
4
4
4
4
4
Shalalth
BC  
3
3
3
3
4
4
4
4
4
Kelowna A
BC   
4
4
4
4
4
4
4
4
4
Kelowna Pc Burnetts Nursery
BC  
2
2
2
2
4
4
4
4
4
Oliver Stp
BC  
3
3
3
3
4
4
4
4
4
Penticton A
BC  
4
4
4
4
4
4
4
4
4
Princeton A
BC  
2
2
2
2
2
2
4
4
4
Summerland Cs
BC  
4
4
4
4
4
4
2
4
4
Vernon
BC  
4
4
4
4
4
4
4
4
4
Castlegar A
BC  
4
4
4
2
2
4
4
4
4
Castlegar Bchpa Dam
BC  
4
4
4
4
4
4
5
5
4
Creston Wpcc
BC  
4
4
4
4
4
4
4
4
5
Duncan Lake Dam
BC  
2
2
2
2
2
2
2
2
2
Fauquier
BC  
3
3
3
3
4
4
4
2
2
Trail Birchbank
BC  
3
3
3
3
4
5
5
5
4
Cranbrook A
BC  
4
4
4
4
4
4
4
4
4
Kimberley Pcc
BC  
3
3
3
3
2
2
4
4
4
Sparwood
BC  
4
4
4
4
4
2
2
4
4
Blue River A
BC  
4
4
4
4
4
4
4
5
5
Kamloops A
BC  
4
4
4
4
4
5
5
5
5
Salmon Arm A
BC  
4
4
4
4
4
2
2
2
4
Golden A
BC  
2
2
1
1
1
2
2
4
4
Mica Dam
BC  
3
3
3
3
3
3
4
2
2
Revelstoke Airport Rd
BC  
4
4
4
4
4
4
4
2
4
Valemount North
BC  
3
3
3
3
4
4
4
2
2
Yoho Nat Park Boulder Cr
BC  
3
3
3
3
4
4
4
5
5
Chetwynd A
BC  
4
4
4
4
4
4
2
4
4
Dawson Creek A
BC  
4
4
4
4
4
4
2
2
2
Fort St John A
BC  
2
2
2
2
2
2
2
2
2
Germansen Landing
BC  
4
2
2
2
2
4
4
4
4
Hudson Hope Bchpa Dam
BC  
2
2
1
1
1
1
1
1
1
Mackenzie A
BC  
2
2
2
2
2
2
2
2
2
Sikanni Chief
BC  
2
2
2
2
2
2
2
2
2
Ware
BC  
3
3
3
3
4
4
4
4
4
Dease Lake
BC  
4
2
4
4
4
4
4
4
4
Fort Nelson A
BC  
4
4
4
4
4
2
2
2
2
Muncho Lake
BC  
4
4
4
4
4
4
4
2
2
Tetsa River
BC  
2
2
2
2
2
2
1
2
2
Atlin
BC  
4
4
4
4
4
4
4
2
2
Pleasant Camp
BC  
4
2
2
2
2
2
2
2
2
Telegraph Creek
BC  
3
3
3
3
2
4
4
4
4
Todagin Ranch
BC  
3
3
3
3
4
4
2
4
4

Extreme rainfall trends in Canada (Environment Canada Engineering Climate Datasets):

Static Maps: http://www.cityfloodmap.com/2015/12/severe-storm-trends-canada-rainfall.html

Interactive Map: http://www.cityfloodmap.com/2015/12/canadian-extreme-rainfall-map-climate.html

Table Summaries: http://www.cityfloodmap.com/2015/12/canadian-extreme-rainfall-summary-by.html

Chart and Table: http://www.cityfloodmap.com/2015/12/top-weather-story-in-canada-2015-less.html

 Long-term Station Table: http://www.cityfloodmap.com/2015/12/long-term-climate-change-short-term.html

Environment Canada Denies Changes: http://www.cityfloodmap.com/2015/10/bogus-statements-on-storms-in-cbcnewsca.html

Contradicting Insurance Industry Claims: http://www.cityfloodmap.com/2015/12/trends-in-canadian-shortduration.html