Regional Climate Change: Current Impacts and Perspectives Greater Lake Nipissing Stewardship Council Annual Meeting Wednesday April 16, 2014

Transcription

1 Regional Climate Change: Current Impacts and Perspectives Greater Lake Nipissing Stewardship Council Annual Meeting Wednesday April 16, 2014 Speaker: Peter Bullock, Stantec Consulting

2 Information Source: This presentation is based on work completed for the North Bay- Mattawa Conservation Authority as part of the Integrated Watershed Management Strategy which is still in progress.

3 Study Area: North Bay-Mattawa Conservation Authority

4 Region climatic characteristics are determined from 14 Stations covering a period of 125 years

5 North Bay Airport Chisholm Township

6 . (3.5 4 o C) Average Annual Temperatures Drinking Water Source Protection: Watershed Characterization, (4 4.5 o C) o C NB Airport 3.8 C Powassan 4.2 C

7 mm/yr. Average Annual Precipitation mm/yr mm/yr NB Airport 1007 mm/yr Powassan 936 mm/yr

8 Known Regional Factors (from previous studies) Lake Nipissing and Georgian Bay have a moderating effect on regional temperatures; Northern Uplands and Almaguin Highlands experience an orographic rainfall effect due to higher elevations The Lake Nipissing basin and the Mattawa lowlands are in a rain shadow and subject to temperature inversions An urban heat island effect occurs over North Bay.

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11 C/yr North Bay Airport o C per year since 1950 Trend not evenly distributed

12 8 of the 10 warmest years since records began at the NB Airport have occurred since was warmest year on record

13 Mean Max/Decade o C Mean Ave/Decade o C Mean Min/Decade o C Until 1980 s average temps were actually declining 1950 and no significant change In 2000 s average temps started trending higher more influenced by rising minimums

14 Normal Mean Max o C Normal Mean Average O C Normal Mean Min o C mean temperatures have increased by 0.67 o C between and which is on par with temperature increases reported globally.

15 Monthly Normal Temperatures C Monthly Normal Temperatures c Temperatures have increased in every month except October Smallest shift is in October/November greatest shift is in December ( o C) and February ( o C)

16 + 2.6 mm/yr precipitation is increasing at an average rate of 2.6 mm/year.

17 5 of the 10 wettest years at the NB Airport have happened since 1998 (all exceeded 1200 mm/year) was the wettest year on record.

18 1960 s - lowest total precipitation 2000 s - highest Rainfall shaped total precipitation until the decade of the 2000 s when snowfall had the greatest influence

19 Overall precipitation is trending higher mm over the 4 normal periods Rainfall shows a steady increase Snowfall was relatively flat until latest normal period

20 September receives most precipitation precipitation is stable or increasing in every month except for August. Precipitation is increasing most in spring and fall with May and October having the largest monthly increases

21 Stantec has examined the water balance of a forested environment typically found within the region Stantec s interest was to examine what changes were occurring over time Assessment assumes that all water not lost to evapotranspiration ends up as runoff.

22 Input Input Main difference is timing of release of water to the environment Same trend as precipitation on an annual basis

23 Output Output ET is not very responsive to annual T & P fluctuation 6 of 7 years that ET exceeded 600 mm/yr) have occurred since 1997

24 Output Annual Average Runoff is adjusting more rapidly Runoff is more responsive to fluctuating T & P and is becoming more erratic over time.

25 Illustration of monthly water balance characteristics - very complex with huge month-tomonth variations Wettest time of the year (Rain + Snow Melt) is March/ April followed by September (Rain) Evapotranspiration directly responds to temperature and directly affects runoff When ET exceeds P - runoff is lowest and dependent on lake and aquifer storage to maintain flows Runoff is highest in April/Nov

26 Table 7.7: Hydrologic Water Balance Calculations for Normal Periods North Bay Airport* Normal Rain and Evapo- Runoff Period Snow Melt transpiration (mm) (mm) % (mm) % Runoff is gaining on evapotranspiration as a water loss factor. Storage is assumed to remain constant in the long term

27 AE is increasing in every month except Oct/Nov which reflects monthly temperature trends

28 Runoff has doubled during the winter period Freshet has shifted from early April to late March and slightly deminished The summer low runoff period is shifting later in the summer and deepening The period between freshet and low summer runoff is widening Runoff is also increasing in Oct Dec period

29 Section 3: Regional Factors Affecting Climate 1. Great Lakes (and Lake Nipissing) influencing regional precipitation Winter Summer

30 Lake Effect - Winter

31 Winter precipitation is greatest where there is a large open fetch of water relative to the prevailing winds (out of the NW) Precipitation accumulations are highest at the edge of the lake and diminishes with distance Lake effect is most pronounced in December/January Shows NBMCA was at the edge of this influence zone during the period

32 Climate Change Impacts to Great Lakes Ice Coverage Ice coverage as of January 22, 2013 Between 1972 and 2010 ice coverage on Lake Huron declined by 62% Ice is forming later and dissipating earlier As northern ice on Georgian Bay\Lake Huron disappears lake effect impacts are starting to encroach into the NBMCA area Ice Concentrations April 10/2014

33 Dec Jan Feb Mar Apr

34 Dec Jan Feb Mar Apr

35 Orographic Effect - Summer

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38 Regional Factors Affecting Climate: 2. Declining August precipitation may reflect changing regional transpiration rates August precipitation rates are declining at a time when Great Lakes evaporation rates should be high Forest transpiration may be evolving as the growing seasons shift earlier causing transpiration to decline by late summer.

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40 Regional Factors Affecting Climate: 3. Topography affects Regional Temperature and Precipitation North Bay Airport data was compared to Powassan

41 Powassan experiences warmer mean temperatures in every month except August Powassan annually is +0.4 o C warmer compared to the North Bay Airport

42 Precipitation pattern is similar North Bay Airport receives more precipitation in most months except in the summer Powassan receives less precipitation overall due to lower elevations Lake Nipissing likely has a significant summer influence but cannot be assessed due to a lack of data

43 Regional Factors Affecting Climate: 4. North Bay Airport Precipitation was compared to monthly precipitation of other regions North Bay Airport monthly precipitation was compared to Ottawa, Sudbury and Huntsville for the period

44 Precipitation in the winter period is remarkable similar North Bay receives about 10% more precipitation Higher precipitation is attributed to North Bay being influenced by the Great Lakes and Lake Nipissing

45 Sudbury s winter precipitation pattern similar to NB Sudbury receives less precipitation in the summer because it is in the lee of Manitoulin Island and has less orographic exposure (348 m) Sudbury may be affected by lack of vegetation in the region from historic mining impacts

46 Winter precipitation in Huntsville is directly effected by lake effect (Dec/Jan) Huntsville receives almost as much precipitation in January as in September Summer precipitation is less because of reduced fetch exposure to GB/LH and it s at a lower elevation (320 m)

47 Flooding and Erosion Events are typically caused by: Spring freshet which is exacerbated by rain Intense thunderstorms Tropical storms (including decadent hurricanes) Global warming is causing severe weather events to increase in all categories, driven by more energy trapped within the troposphere.

48 Insurance Bureau of Canada examined the frequency of severe weather events in Canada: The number of days with extreme heat, which can cause intense rainfall events, have increased Water conveyance infrastructures such as storm sewers, bridge openings, and constructed channels that use probability information to determine appropriate sizing are being affected In some parts of Canada, storms once experienced every 40 years are now being observed every 6 years on average

49 In the 60 year period the average number of extreme heat days increased from 1.5 to 3 events/year 2005 had the highest number =14

50 Highest probability month has shifted from July to August in 2000 s Period of extreme heat probability is widening to cover all summer months

51 An intense thunderstorm hit Bonfield and East Ferris on August 5, 2008 that resulted in extensive flooding - rainfall near the center of the impact zone exceeded 120 mm over a 6 hour period (est. to be ~ 1:200 year event?) The severity of this event was not captured at either active weather station based on data obtained from amateur sources

52 This historic radar image is for August 5, 2008 at 4:00 pm as the storm started to impact East Ferris as indicated by the red arrow

53 Storm lasted ~ 8 hrs

54 Section 5: Climate Change Projections: Stantec populated Temperature and Precipitation projections for North Bay and Powassan using a tool called the Localizer (from Canadian Climate Change Scenarios Network) Projections are based on an A2 - High Emission Scenario

55 C annual winter spring summer autumn s 5.1 ± ± ± ± ± s 6.6 ± ± ± ± ± s 8.5 ± ± ± ± ± 1.0 Comparable to mean annual temperature of Orillia 6.5 o C

56 mm annual winter spring summer autumn s ± ± ± ± ± s ± ± ± ± ± s ± ± ± ± ± Annual Precipitation to increase by ~80 mm by 2050 Annual Precipitation projected for the 2020 s has already been reached? ( normal period averaged 1044 mm at the NB Airport Precipitation is projected to increase in every season except for the summer period

57 C annual winter spring summer autumn s 5.5 ± ± ± ± ± s 6.9 ± ± ± ± ± s 8.7 ± ± ± ± ± 0.9 Comparable to mean annual temperature for Barrie 6.7 o C

58 mm annual winter spring summer autumn s ± ± ± ± ± s ± ± ± ± ± s ± ± ± ± ± 33.3 Annual average precipitation to increase by ~ 60 mm by 2050 Same summer declining trend as NB Airport

59 North Bay Airport "Record Years" Precipitation Temperature Rain Snow Total Max Mean Min nd rd th th th th nd th st rd th st 9 of 15 are record setting years

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62 An abrupt change in 1997/98 has transformed the region into a new climatic period and this shift is reverberating through climatic normals for the region The concept of normal is now outdated or a misnomer. Climate is no longer static it now is a dynamic variable 2014 so far has seen an unexpected extreme which may be a fluke year or a sign that something else at a global scale has shifted and open the door to the Polar Vortex Only time will tell!

63 Thank You! I like to express my thanks to the North Bay - Mattawa Conservation Authority for conducting climate research and allowing the data to be used in this presentation