At the Interim Results Workshop, the Modeling Team presented the climate change and hydrological modeling results for the LMB. The modeling team consists of Mr. Tarek Ketelsen, Mr. Jorma Koponen, Mr. Jeremy Carew-Reid, Mr. Simon Tilleard, Mr. Mai Ky Vinh, and Mr. To Quang Toan.
Mekong ARCC Climate Change and Hydrology Modeling Methods and Results
1. Climate and
hydrological
change:
methods and
results
Tarek Ketelsen
Jorma Koponen
Jeremy Carew-Reid
Simon Tilleard
Mai Ky Vinh
To Quang Toan
ICEM – International Centre for Climate Change Impacts and Adaptation Study
Environmental Management Interim Results workshop
31 October – 1 November 2012
2. Contents
1. Climate change and the Mekong Basin
2. Overview of the methodology
3. Basin-wide findings
4. Challenges & limitations
2
4. Hydroclimate features of
the Mekong Basin
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CHIANG SAEN
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1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec
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5. Climate
changes
Hydrological
changes
Agricultural Ecological
zones zones
Species “zones”
Commercial Subsistence Aqua- Traditional Live- Crop wild NTFPs Wild fish Wildlife
crops crops culture crops stock relatives catch
Climate
Adaptation options
changes
Hydrological
changes
Agricultural Ecological
zones zones
Species “zones”
Commercial Subsistence Aqua- Traditional Live- Crop wild NTFPs Wild fish Wildlife
crops crops culture crops stock relatives catch
Adaptation options
6. ARCC time-slices
• ARCC Vulnerability Projections centered on 2050 (2045-2069)
– 2050 allows for identification of the CC trends to be established with
confidence
– show us what direction we are moving, helping to set adaptation
response
• ARCC will also consider 2030 and Global 2 C
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7. 2 C – a compromise with nature to avoid catastrophic climate change
> 2 C → + 2 to 7m SLR
>300yrs
> 3-5 C → +5 m SLR > 2 C → ????
>300yrs
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Source: Adapted from (Schellnhuber, 2012and Lenton et al 2008)
8. Global CC projections
B1
• Population peaking
at 9bil. and declining
after 2050
• Reductions in
material intensity
• Aggressive
transition to clean &
resource efficient
technologies
• Emphasis on
globally connected
economies
• Over last decade rates of C0₂ emissions have exceeded even the most
extreme scenarios
– 2008 emissions +37% above 1990 levels
– 2010 emissions +5% above 2008 8
– Increased mean global temperatures by 0.8 C
Source: IPCC, 2007
9. Emission thresholds
• Budget of 750Gt C0₂ remaining
before we reach 2°C
• Global emissions for all GHGs
need to peak by 2015-2020
• 5-9% annual emissions
reduction rate
• 25-40% emissions reduction
of developed countries by
2020
• 50% global emissions
reduction by 2050
Source: WBGU Special Report 2009
• Unlikely that climate change can be limited to 2 C
• Vulnerability assessments need to project beyond 2 C to
understand the trends 9
• By 2050, the Mekong Basin is beyond 2 C
11. Assessment steps
MEKONG HYDROCLIMATE MEKONG SYSTEMS BASELINES
BASELINE
Hydrological Floodplain Crop Yield Crop suitability
modelling modelling modelling modelling
CHARACTERISATION OF EXPOSURE CHARACTERISATION OF
SENSITIVITY
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MEKONG SYSTEM CAM ASSESSMENT
12. Projections of future emissions
and global GHG concentrations
IPCC EMISSION SCENARIOS
A1 B1 A2 B2
Hydroclimate Projections of future atmospheric climate, atmospheric & ocean
dynamics
assessment process BCCR-
GCMs – GLOBAL CIRCULATION MODELS
CCSM3 CGCM3.1 CGCM3.1 CNRM- CSIRO - ECHMA5/ ECHO-G
BCM2.0 (T47) (T63) CM3 MK3.0 MPI-OM
FGOALS- GFDL- GFDL- GISS- GISS-EH GISS-ER INM- IPSL-CM4
G1.0 CM2.0 CM2.1 AOM CM3.0
MICROC3. MICROC3.2 MRI- PCM UKMO- UKMO-
2 (hires) (medres) CGCM2.3. HADCM3 HADGEM
2 1
Downscaled projections of future climate at
the basin-level
CLIMATE DOWNSCALING
DYNAMICAL STATISTICAL PATTERN
(PRECIS)
PRECIS Vietnam 2009 Mekong Basin 2009
Southeast (WeADAPT) (Cai et al, 2008)
Asia 2003
(SEASTART)
Prediction of future hydrological regime
HYDROLOGICAL MODELLING
VMOD VMOD MRC DSS VMOD SLURP CSIRO
Songkhram Mekong Delta Mekong Mekong Mekong Mekong
2004 2008 Basin 2010 Basin 2011 Basin 2011* Basin 2009
(Aalto Uni & (Aalto Uni & (MRC & (Aalto Uni & (QUEST) 12 (18 sub-
SEASTART) SEASTART) IWMI) ICEM) (no Mekong basins)
floodplain)
13. Key steps
1. Projections of future emissions
• Quantification of future
climate change threats
• Links changes in global 2. Projections of future atmospheric
systems to regional and and ocean dynamics
local areas of interest
• Based on best available 3. Downscaling projections to the
Mekong Basin
science
4. Predicting future changes in the
basin hydrological regime
5. Predicting future changes in the
Delta floodplain environment &
project site
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14. 1. IPCC Emissions Scenario
A1B
• world of rapid economic growth
• introduction of more efficient technologies
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• global population peaking by 2050 (9bil.)
• a balance between fossil intensive and non-fossil energy sources Source: CSIRO, 2009
15. 1. IPCC Scenarios – new developments
IPCC AR5 (2014)
• SRES scenarios will be replaced with a set of
Resource Concentration Pathways (RCPs)
– a set of scenarios relating to radiative forcing and
GHG concentrations in the atmosphere
– not directly linked to any socio-economic futures
• Can be linked to IPCC scenarios
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Source: Moss et al, 2012
16. 2. Global Circulation Models
• Two earlier studies (Cao et al, 2009; Eastham et al, 2008) reviewed the
performance of 17/24 IPCC AR4 GCMs for suitability to the Mekong region
• In general, models perform better for temperature than precipitation
• 6 were chosen based on their ability to replicate daily historical temperature and
rainfall data
Climate model CO2 Scenario Abbreviation Data period Model resolution (degrees)
CCCMA_CGCM3.1 A1b, B1 ccA, ccB 1850-2300 3.75° x 3.75°
CNRM_CM3 A1b, B1 cnA, cnB 1860-2299 2.8° x 2.8°
GISS_AOM A1b, B1 giA, giB 1850-2100 3° x 4°
MIROC3.2Hires A1b, B1 miA, miB 1900-2100 1.1° x 1.1°
MPI_ECHAM5 A1b, B1 mpA, mpB 1860-2200 1.9° x 1.9°
NCAR_CCSM3 A1b, B1 ncA, ncB 1870-2099 1.4° x 1.4°
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17. 3. Statistical Climate Downscaling
Purpose: reduce the geographical scope so that resolution
can be improved
Assumes local climate is conditioned by large-scale
(global) climate
does not try to understand physical causality
GCM output is compared to observed information for a
reference period to calculate period factors
Period factors are then used to adjust GCM time-series
Downscaling undertaken for 166 temperature &
precipitation stations
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18. 4. Basin wide hydrological modelling
• VMod model
• 15 years of custom development for the Mekong
• area-based distribution of hydro-meteorological
impacts of climate change
• Computes water balance for grid cells (5x5km)
• Baseline:1981 – 2005
• Future CC: 2045 - 2069
• Can predict changes in:
– Rainfall
– Runoff
– Flows
– Infiltration
– evapotranspiration
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19. 5. Flood modelling
• MIKE-11
• Uses Vmod to establish
boundary conditions
• Divides the floodplain into
zones (>120 in the delta)
• Calculates small area water
balances
– 25,900 water level points
– 18,500 flow points
• Quantifies the changes in depth
and duration of flooding due to
changes in upstream hydrology
and sea level rise
Flooding Assessment scenarios
• Average Flood + 0.3m SLR
• 1 in 100yr Flood + 0.3m SLR 19
• 1 in 100yr Flood + 0.3m SLR + Cyclone event
21. CC assessment parameters
• Max/min daily Temperature
• Seasonal rainfall
• Timing of the monsoon
• Peak rainfall events
• Erosion potential
• Drought
• Storms & cyclones
• Soil water availability
• River flow
• Hydro-biological seasons
• Flooding (depth & duration)
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22. Interpreting Climate Change: Shifts & variability
1. Shift in the Mean
2. Historic variability 1
3. future variability
3–2= variability
4. Climate experienced in baseline
but no longer experienced with
CC
5. Climate common in baseline but
less frequent with CC 3
6. Climate becoming more
frequent with CC 2
7. New climate never before
experienced
4 5 6 7
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36. Agricultural Drought
Rainfall < 0.5* PET
Increase in areas experience >6months drought
- 3 -25%
+10-100%
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37. Change in Storm Events
Baseline summary (1956-2009)
Date Intensity Frequency Landfall
June Japan, Korea, China
+ + Eastern Seaboard
July China, Northern Vietnam
++ + & Lao PDR
25%
Aug – +++ +++ Northern & central
Vietnam & Lao PDR –
Sep occasionally Thailand
15%
Oct – ++ ++ Central Vietnam,
Southern Lao &
Nov Cambodia
Dec Southern Vietnam
+ +
41%
With CC:
19% • Frequency will not change
• Become more intense
• Unclear whether trajectories will
change
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52. Key challenges for climate change modelling
1. Topographical complexity of the basin
2. Variability in Mekong hydroclimate &
selection of appropriate baseline
3. Non-stationarity in hydroclimate
conditions
4. Understanding of Ground water
interactions
5. Application of statistical downscaling
in tropical climates (validity of the
normal distribution assumption)
6. Accounting for system feedback
– projecting changes in the stability of the
Monsoon
– Incorporating ENSO phenomena
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Source: MRC, 2011
2°C is the key target in global climate discussions, these COP conferences etcWe have 194 countries trying to get global agreement on this targetThe reason for 2Deg C is not to avoid CC impacts. We know that with 2deg we are going to have impacts .The reason is to avoid some of the catastrophic impacts – the global tipping points – destabilisation of the indian monsoon, collapse of the greenland or antarctic ice sheets etc… these will fundamentally transfrom the world in ways which will really threaten our ability as a species to surviveBut is 2Deg C realistic?
we know there is an approximately linear (Quasilinear) relationship between atmospheric CO2 and global temperature change
Two key features of the distribution: the mean around which the distribution is centered. The spread in the data – i.e. the range in variability of the parameter
Globally by 2050 mean annual temperatures will increase by 1.2-2.2 Deg CIn the LMB mean annual temperatures will increase by xxx Deg C
Maybe delete as this info is covered better in the next slide
Identify the major floodplains of the Mekong and show Cambodia/Delta floodplain to be the dominant one
Due to its size, the Mekong basin is compromised of highly variable terrain. Upland areas of the Annamites and northern Lao are extremely rugged with poor access. This means that hydroclimate conditions vary markedly over short distances while coverage of monitoring stations remains sparse (see Section 3.1.3.5). In these areas localised high points, such as karst formations which rise rapidly, can occur in flatter valley terrain and cannot be accurately picked up by the Digital Elevation Model (DEM) used to define topography. The DEM will resolve the topography into an average elevation within the cell which will be higher than the valley level but lower than the local peak, which means that elevations for valley areas could be overestimated while the high point will be ignored. This issue is symptomatic for all hydrological modelling work in the Mekong Basin and can only be resolved through the development of higher resolution topographical data.Groundwater remains the most poorly monitored water resource in the Mekong basin, yet plays an important role in monthly, seasonal and inter-annual water storage. In some areas such as central Lao PDR, there is evidence suggesting that groundwater discharges back into streams during the dry season (table 3-1). Application to tropical climates: typically statistical downscaling uses multiple regression techniques which assume climate data is normally distributed. While this is generally the case for temperature data it may not the case for precipitation in monsoon.System feedback: changes in the hydroclimate will influence changes in other ecosystem components such as vegetation which could feedback to the hydroclimate by altering micro-climates, onset dates of seasonal rains, convection dynamics in the regional atmosphere or the persistence of dry spells. Statistical models fitted to observational data do not have the capacity to pick up on these important feedbacks.