Long-range Forecast of Climate Change: Sri Lanka Future Scenario. G. B. Samarasinghe Director General of Meteorology

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1 Long-range Forecast of Climate Change: Sri Lanka Future Scenario G. B. Samarasinghe Director General of Meteorology 1

2 Line-up Global and Regional Future Scenarios Observed and Potential Impacts Observed and Potential Impacts and Scenario of Sri Lanka Sri Lanka Future Scenario Development and Adaptation Gap Identification

3 Global and Regional Scenarios

4 What s in the Pipeline and What Could Come Warming will increase if GHG increase. If GHG were kept fixed at current levels, a committed 0.6 C of further warming would be expected by More warming would accompany more emission. CO2 Eq 3.4 o C = 6.1 o F 2.8 o C = 5.0 o F o C = 3.2 o F 0.6 o C = 1.0 o F 400

5 Projections of Future Changes in Climate New in AR4: Drying in much of the subtropics, more rain in higher latitudes, continuing the broad pattern of rainfall changes already observed.

6 What else Happens in a Hotter World? Observations of sea level rise from satellites, The global average SLR for the 20th century was about 6 inches (0.17m), mostly from expansion of the hot ocean, and with contributions from glacier melt (Alaska, Patagonia, Europe.). Future changes just from these processes could be up to 1.5 feet (0.5 m) by 2100, and up to 3 feet (1 meter) within about 2-3 centuries, depending on how much GHGs are emitted. But what about other processes? Rapid ice flow?

7 Observed and Potential Impacts

8 Sea level rise is one of the surest consequences of a warmer climate Increased vulnerability of coastal areas (mangrove, coral reefs, ecosystems and safety) Flooding Salinization of fresh water Beach erosion Damage to infrastructure Sanitation Climate Change may change frequency of extremes in the water cycle river upstream heavy rainfall creating coastal flooding Increased storm surge

9 Regional Temperature and Precipitation Changes Source: WMO-UNEP Working Group 2 of IPCC

10 Examples of Global Impacts Projected for Changes

11 Examples of Regional Impacts

12 Observed and Potential Impacts and Scenario of Sri Lanka Developed in different stages by Mr L Chandrapala, Dr B R S B Basnayake, K H M S Premalal, D A Jayasinghearachchi with Research Assistants in the DOM and Dr B V R Punyawardena of Department of Agriculture.

13 Seasons First inter-monsoon (March April), Southwest monsoon (May Sept), Second inter-monsoon (Oct Nov) Northeast monsoon (Dec Feb).

14 Climatic Zones (Annual total rainfall) Wet zone (> 2500mm) Intermediate zone ( mm) Dry zone(<1250mm).

15 Observed Changes in Climate Temperature ( & ) Station Minimum Maximum Mean Minimum Maximum Mean Nuwara Eliya Anuradhapura Ratnapura Kurunegala Colombo Puttalam Decrease of Maximum temperature, only in Nuwara Eliya, 1894m above msl.

16 Observed Changes in Climate Temperature ( & ) Annual Maximum airtemperature anomaly trend in Nuwara- Eliya y = x R 2 = Tmax Anomaly in C (from ) year Nuwara Eliya, 1894m above msl.

17 Other Impacts Cold days and nights decreased Warm nights and days increased Consecutive dry days increased 24 hr heavy precipitation increased, especially along the western slopes of Central hills

18 Consecutive Dry Days (Basnayake, B.R.S.B; Premalal, K.H.M.S. 2006).

19 Consecutive wet days decreased all over the country High Rainfall variability

20 Extremely Heavy Rainfall

21 Total Rainfall

22 10 24hr Heavy Rainfall Trend ( & ) 9.5 Higher increasing trend in Southwestern areas Mostly due to southwesterlies (due to Monsoon or cyclonic disturbances) Either due to direct or indirect effect of cyclonic disturbance

23 Season Coefficient of Variation of all Sri Lanka Rainfall Northeast Monsoon (Dec. to Feb.) 31% 42% First Intermonsoon (Mar. to Apr.) 23% 27% Southwest Monsoon (May. to Sep.) 21% 16% Second Intermonsoon (Oct. to Nov) 22% 23% Annual (Jan. to Dec.) 12% 14% The Coefficient of Variation of all-sri Lanka Rainfall during the periods and , (Chandrapala, 1997)

24 Station Topographical Location Coefficient of Variation (%) Colombo Low Country 21% 20% Galle Low Country 28% 12% Ratnapura Low Country 23% 15% Kandy Mid Country 21% 22% Kenilworth Mid Country 37% 17% Talawakelle Up Country 28% 21% Nuwara-Eliya Up Country 26% 13% Coefficient of Variation of southwest monsoon rainfall at selected stations in low, mid and up country regions during and periods (Basnayake and Punyawardane, 2003)

25 Trend in Tropical Cyclone Frequency Annual total number of cyclones Frequency Year y = x R 2 =

26 Trend in Depression Frequency Num ber of annual depressions ( ) Frequency Year

27 Trend of Cyclonic Disturbance Formation Slight significant decreasing trend of the occurrence of cyclones Decreasing (or Sinusoidal?) trend with a peak of depressions during the period

28 Sri Lanka Future Scenario Based on AR 3

29 GCM - HadCM3 (Hadley Centre Model) Rainfall Scenarios under A 2 Storyline

30 Baseline ( ) average Rainfall in Northeast Monsoon (NEM) Baseline ( ) average Rainfall in Southwest Monsoon (SWM)

31 NEM Rainfall in 2025 Under A 2 Storyline SWM Rainfall in 2025 Under A 2 Storyline

32 NEM Rainfall in 2050 Under A 2 Storyline SWM Rainfall in 2050 Under A 2 Storyline

33 NEM Rainfall in 2100 Under A 2 Storyline SWM Rainfall in 2100 Under A 2 Storyline

34 Rainfall Change Scenario in SWM under A 2 Scenario Increment over the baseline mm 402 mm 1061 mm

35 Rainfall Change Scenario in NEM under A 2 Scenario (AR3) Increment over the baseline mm 54 mm 143 mm

36 GCM - HadCM3 (Hadley Centre Model) Mean Temperature Scenarios under A 2 Storyline

37 Baseline average T mean in Northeast Monsoon Baseline average T mean in Southwest Monsoon

38 NEM T mean in 2025 Under A 1 storyline SWM T mean in 2025 Under A 2 storyline

39 NEM T mean in 2050 Under A 2 storyline SWM T mean in 2050 Under A 2 storyline

40 NEM T mean in 2100 Under A 2 storyline SWM T mean in 2100 Under A 2 storyline

41 Mean Temperature change scenario under A 2 Scenario (Annual) Increment over the baseline C C C C Best Guess

42 Development and Adaptation-I Mainstreaming Climate Change for Sustainable Development in Sri Lanka Science and Economics of Climate Change- Adaptation Adaptation Imperative Many impacts can be avoided, reduced or delayed by mitigation Choice of development pathway - a key to reducing impacts of climate change mixture of adaptation and mitigation measures, to meet the challenges of CC

43 Development and Adaptation-II Development increases resilience Adaptation will put strong pressure on developing country budgets Adaptation planning, with reduced uncertainties Supports for adaptation Disaster response Crop varieties and technology Forecasting climate and weather

44 Gap Identification Sri Lanka Future Climate Scenario (AR 4) Development Sectored Impact Assessment Expert Collaboration- External Assistance Human Resources and Capacity Building Financial Assistance for software and Foreign Expertise

45 Sophisticated Tools: Down-scaling Coarse GCM + High resolution AGCM Variable resolution GCM (high resolution over the area of interest) GCM + RCM or LAM (Nested Modeling Approach) More accurate downscaled results as compared to the use of GCM outputs alone. Spatial scales for RCM results ~ 20 to 50 km still large for many hydrologic models. Superior computing resource requirements

46 Downscaling Methods RCM or LAM (Dynamic Downscaling) GCM preferred Statistical Models (Statistical Downscaling) Stochastic Weather Generators Weather Typing or Classification Impact Models (Hydrologic Models) Regression Models low resolution ~ 300 km month, season, year high resolution 1 km day, hour, minute

47 Bridging the Gap Foreign assistance search for Scenario and Sector Impact Assessment in progress Embed Climate Change related activities as a priority in National Planning In addition to external funding, Treasury allocations for Climate Change related activities in Institutions

48 Some Points (I) All are based on computer model output Can not differentiate human caused/ natural Incomplete models can produce past well. Future?? No testing ahead of time Long term climate studies==> Earth goes through large and small scale weather and climatic patterns, based on solar energy output and solar flare activity, wobbles of the Earth s rotation, changes in land locations (continental drift), periodic melting and reformation of glaciers and much more. May be at a peak of normal oscillation, and might fall in time Humans do affect; but not the cause? No measurable warming of average global temperature since 1998 Decreasing solar activity in early 21 st century Current warm interglacial period has already lasted years and inevitably followed by glaciations ==> cooling??

49 Some Points (II) With current understanding of anthropogenic climate change & History of human influence on climate Can collective lifestyle avert an unprecedented and potentially catastrophic disaster? Will mitigation and adaptation be enough? To attempt to fix the climate change through geoengineering (deliberate modification of Earth's environment on a large scale "to suit human needs and promote habitability". The term geoengineering is distinct from accidental anthropogenic climate change)?? Isn't it better to make scenarios and public policy with a knowledge of history??

50 Thank You