Systems at risk: Climate change and water for agriculture

Transcription

1 Systems at risk: Climate change and water for agriculture Jean-Marc Faurès Land and Water Division FAO-WB Workshop on Climate Change Adaptation in Agriculture in East Asia and the Pacific FAO, Rome, May 16-17, 2011

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3 What is happening?

4 Global warming: historical temperature change Source: EEA, based on NASA's GISS mean land-ocean temperature anomalies and the Hadley Center's HadCRUT3 dataset.

5 Drought severity in the rise Palmer drought severity index (PDSI) Source: Dai, 2004 in IPCC

6 Source: IPCC

7 Sea level rise

8 What do we think will happen

9 Water and climate change (IPCC forecast) Precipitation intensity and variability are projected to increase the risk of flooding and drought in many areas: frequency of heavy precipitation events will be very likely: floods proportion of land surface in extreme drought likely to increase: droughts Increase in evapotranspiration demand due to higher temperatures Regionally variable but significant changes in soil moisture In places, significant reduction in river runoff and aquifer recharge reduced storage of snow and earlier melting of winter snow, leading to change in runoff regime of large rivers (earlier flood seasons) Inundation and increased damage in low-lying coastal areas affected by sea level rise, with storm surges and increased sea water instruction into vulnerable freshwater aquifers; CLIMATE CHANGE WILL AFFECT ALL THE ELEMENTS OF THE WATER CYCLE (Source: IPCC Technical report VI: Climate change and water)

10 Mean and extreme change Frequency, extent and severity of extreme events important for AWM impacts: Floods Droughts (Interannual / seasonal) Cyclones Coastal surges [IPCC, 2005]

11 Amplification effect of change in rainfall Source: Rossel, (WWD and FAO).

12 Percentage change Uncertainty in runoff prediction Source: Chiew et al., 2010.

13 Link between climate change, water and crop production

14 Increased evaporative demand Change in irrigation water demand Faster reduction in soil moisture Longer dry spells, droughts Earlier snow and glacier melt Higher peak flows, longer periods of low flows Change in groundwater recharge Change in irrigation water availability

15 A focus on systems at risk

16 A typology of systems at risk

17 Impacts are context specific System at risk Large surface irrigation systems Deltas and coastal areas Semi-arid tropics groundwater systems Humid tropics Increased evaporative demand XX XX XX X Droughts XX X XXX XX Floods X XXX X XX Change in runoff patterns Groundwater recharge Sea water intrusion/ cyclones XXX XX XX X X XX XXX XXX

18 1. Snow-melt systems

19 Higher Mekong: change in snowmelt depth A2(left and B2 (right) scenarios. Difference between and Source: CSIRO, MRC, IWMI Adaptation Options to Reduce the Vulnerability of Mekong Water Resources, Food Security and the Environment to Impacts of Development and Climate Change

20 2. Deltas: highly vulnerable Inundation depth for 30 cm sea level rise Source: World Bank Vietnam: Economics of Adaptation to Climate Change. Washington, DC: World Bank.

21 3. Semi-arid and arid tropics

22 3. Semi-arid tropics: vulnerability of groundwater Quantity and quality issues arising from reduced recharge Current and foreseeable depletion and future recharge Mitigating importance of over bank flood flow on recharge World Bank region Sensitivity Utilization of groundwater Climate change impact on recharge Exposure SLR 1 & storm surge exposure Adaptive capacity Per capita GNI 1 Vulnerability 2 East Asia & Moderate Increase Medium Moderate Moderate Pacific Europe & Low Increase Low High Low Central Asia Latin America Moderate Reduction Medium Moderate Moderate & Caribbean Middle East & High Uncertain Low Moderate Moderate North Africa South Asia Moderate Negligible High Low High Africa Moderate Reduction Low Low High Source: World Bank 2009

23 4. Humid tropics: managing floods and droughts

24 Response options: Implications for future investments

25 Principles for adaptation Adoption of no regret investment strategies Build robustness in decision making (planning): Systematic use of scenarios: check response to different situations: resilience. Infrastructure resilience audits Adaptive management Flexible, able to adapt to changes Based on continuous social and institutional learning Based on strong monitoring and information management allowing for rapid adaptation increasing importance of knowledge, information and monitoring

26 Scales of response River basin National International Irrigation scheme Field/farm

27 Farm level (mostly autonomous) Crop/irrigation technology Crop husbandry Changes in cropping patterns Soil & water management, including better water conservation techniques avoid maladaptation through capacity building, incentives and information

28 Irrigation scheme level (build flexibility) Managing water allocation & use Storage management Groundwater use and recharge Water measurement and accounting Improving irrigation system performance Re-engineering of irrigation systems Adjusting operation, monitoring and regulation practices Flood management

29 Basin Level: Trade-offs, balance and equity Catchment management and land use policy Investment priorities Broad strategy on agricultural development and support Rainfed Irrigated Water allocation across sectors: Water development options Reallocation Environmental allocation Disaster risk management & preparedness

30 Thank you