The Impacts of Climatic Variability and Climate Change on Water Resources in Western Canada

Transcription

1 Alberta Irrigation Projects Association Conference 2001 Water Strategy. Because every drop counts November 19, Lethbridge, Alberta The Impacts of Climatic Variability and Climate Change on Water Resources in Western Canada D. S. Lemmen; ; Natural Resources Canada dlemmen@nrcan.gc.ca

2 AIPA Conference 2001 issues: on-farm water management upstream / downstream water demands responding to drought technology efficiency / expansion water storage / transfers what is the relevance of climate change to these issues?

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4 Outline of Presentation 1 - Climate change and the Greenhouse effect 2 - The latest scientific consensus at the global scale 3 - Projections for Canadian prairies and southern Alberta 4 - Lessons from the past 5 - Adaptation as a means of addressing climate change 6 - Research needs to move forward

5 Climate is Always Changing Ice cores, tree rings, lakes and oceans sediments: windows on the past From GSC Misc. Report 71 (2001)

6 The Greenhouse Effect is Real Incoming energy Outgoing energy Reflected energy Energy trapped by greenhouse gases (GHGs) Major Greenhouse Gases - water vapour, carbon dioxide, methane, nitrous oxide, ozone Enhanced Greenhouse effect - more CO 2, CH 4, N 2 O + halocarbons Aerosols - not a GHG - microscopic particles, natural sources, sulphur dioxide, burining

7 Intergovernmental Panel on Climate Change - Third Assessment Report (IPCC TAR) 2001 TAKE HOME MESSAGES Working Group 1 - THE SCIENTIFIC BASIS Global-average surface temperatures increased about 0.6 o Cin past 100 years, the 1990 s the warmest decade in past 1000 years. new and stronger evidence that most of the warming observed in the past 50 years is attributable to human activities atmospheric concentrations of greenhouse gases have continued to increase as a result of human activities the globally averaged surface temperature is projected to increase by 1.4 to 5.8 o C over period

8 Global (140 years) and Northern Hemisphere (1000 years) temperature records

9 Climate Change involves both human and natural factors

10 Global atmospheric concentrations of main greenhouse gases over time

11 Temperature Projections for 21st Century

12 Projected Temperature Change between 1910 and 2040 AD Combined Effect of Projected Greenhouse Gas and Sulphate Aerosol Increases.- Canadian Model

13 Meeting the Kyoto Protocol: the challenge Greenhouse Gas Emissions, 800 MT / year Business-as-Usual 764 MT* *Business-as-usual scenario factors in an estimated 60 MT of reductions from current voluntary measures MT (+13%) MT MT GAP -25% Kyoto Target 575 MT

14 The REAL Challenge B.A.U. Kyoto Kyoto Is An Important First Step (delays doubling by about 20 years)

15 Enough already!! What does it mean to ME???

16 Projections for future climate of the southern Alberta (broad generalizations recognizing variations between models) Temperature: Precipitation: Evaporation: increasing, greater in winter than summer, greater at night than during day great uncertainty, annually small increase to significant decrease increased Soil moisture: decreased Growing season: increased Atmospheric CO 2 : increased Extreme events: Hydrology: increased frequency and magnitude increased variability, earlier peak flows, glaciated headwaters (Bow) more resilient than basins with nival headwaters (Oldman)

17 Projected changes in moisture deficit (P-PE) Top: Bottom: PFRA (2001)

18 Changes in Land Suitability Rating System Climatic Classification Top: Bottom:

19 Impacts highlighted in Canada Country Study (Herrington et al., 1997) Agriculture irrigation may become less attractive if water supplies become more uncertain Water Supply and Demand existing water control structures could be impacted increasing conflicts between multiple consumptive needs

20 So what if it s a bit warmer?? Climate change and extreme climatic events

21 Prairie Drought: Lessons for the (distant?) past Past Prairie Droughts Recorded in Tree Rings

22 Prairie Drought: Lessons for the (distant?) past During extreme low water phases, some prairie lakes deposit unique laminated sediments Antelope Lake, Saskatchewan ca.1000 years ago: drought intervals lasted for several decades ca years ago: water tables >4 to 14 m blow present levels

23 Addressing Climate Change: Mitigation and Adaptation Climate Change Impacts Mitigation Adaptation Responses

24 ADAPTATION Adaptation can be spontaneous or planned and can be carried out in response to, or in anticipation of changes in conditions. Represents a practical means of accommodating current climatic variability and extreme events, as well as adjusting to longer term climatic change. Irrigation has historically represented an effective adaptation strategy to address moisture limitations on agriculture in the dry prairies What Future Challenges Need to be Faced?

25 Research Needs (can only be addressed with stakeholder involvement at every stage) 1 - to assess the vulnerability of irrigation agriculture in southern Alberta to climate change Vulnerability is a function of climatic sensitivity and adaptive capacity 2 - define critical thresholds (stakeholder defined) water availability (supply) competing consumptive uses (demand) 3 - assess adaptation options technology / efficiency alternative water sources (groundwater)

26 Risk Assessment & Coping Range TH2 TH1 Coping range TH1 Climate variable Realistic climate change impact assessments must take adaptation into account (Pittock and Jones, 2000)

27 Keys to moving forward activities well adapted to current climatic variability are best positioned to address climate change do not base design criteria solely on historic climate maximize flexibility recognizing uncertainty and need to accommodate extreme climatic events consider climate change as just another factor in your risk management strategy define and monitor systems relative to critical thresholds

28 Where can I get more information? a facilitative, interdisciplinary research network established to understand the potential impacts of climate change on the Canadian Prairie Provinces and conduct research necessary to develop appropriate adaptation strategies.

29 Other useful web sites Understanding Climate Change Canada s Climate Change Process Impacts and Adaptation