Transcript Global water resources stresses

Global Hydrology Modelling:
Running Multiple Ensembles with
the Campus Grid
Simon Gosling
Walker Institute for Climate System Research,
University of Reading
Thanks to
Dan Bretherton (Reading e-Science Centre)
and
Nigel Arnell (Walker Institute)
Outline
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The hydrological model & project background
Projected changes in global annual runoff
Projected changes in seasonal runoff
Projected changes in global water resources stresses
Description of the Hydrological &
Project Background
The hydrological model: Mac-PDM
• Mac-PDM is written in Fortran and simulates river
flows across the globe on a 0.5x0.5 degree grid.
• Input data from global climate models (GCMs):
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–
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Rainfall
Temperature
Humidity
Windspeed
Cloud cover
The NERC QUEST-GSI project
• Aim is to examine the global scale impacts of climate change
on the hydrological cycle and water resources.
• If global temperature was to rise by a certain amount, what
would the impacts be?
- Investigate impacts for the following 9 prescribed mean global
temperature changes relative to present:
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+0.5ºC
+1.0 ºC
+1.5 ºC
+2.0 ºC
+2.5 ºC
+3.0 ºC
+4.0 ºC
+5.0 ºC
+6.0 ºC
The NERC QUEST-GSI project
• The climate data is taken from an ensemble of
GCMs to explore the role of climate model
structural uncertainty.
Source: Collins et al.
(2006) Towards
quantifying uncertainty
in transient climate
change. Climate
Dynamics 27: 127-147
Running on the campus grid
GCM used to provide climate data
Prescribed Temperature
Running on Linux Desktop:
0.5
1.0
1.5
2.0
2.5
3.0
4.0
5.0
6.0
UKMO HadCM3
x
x
x
x
x
x
x
x
x
1 run = 3 hours
CCCMA CGCM31
x
x
x
x
x
x
x
x
x
IPSL CM4
x
x
x
x
x
x
x
x
x
9 runs = 27 hours
MPI ECHAM5
x
x
x
x
x
x
x
x
x
NCAR CCSM30
x
x
x
x
x
x
x
x
x
BCCR BCM20
x
x
x
x
x
x
x
x
x
CCCMA CGCM31T63
x
x
x
x
x
x
x
x
x
CCSR MIROC32HI
x
x
x
x
x
x
x
x
x
CCSR MIROC32MED
x
x
x
x
x
x
x
x
x
CNRM CM3
x
x
x
x
x
x
x
x
x
CSIRO MK5
x
x
x
x
x
x
x
x
x
GFDL CM21
x
x
x
x
x
x
x
x
x
GISS AOM
x
x
x
x
x
x
x
x
x
GISS MODELEH
x
x
x
x
x
x
x
x
x
GISS MODELER
x
x
x
x
x
x
x
x
x
IAP FGOALS10G
x
x
x
x
x
x
x
x
x
INM CM30
x
x
x
x
x
x
x
x
x
MRI CGCM232A
x
x
x
x
x
x
x
x
x
UKMO HadGEM1
x
x
x
x
x
x
x
x
x
171 runs = 513 hours (21 days)
On the campus grid:
171 runs = 9 hours
Projected Changes in Global
Average Annual Runoff
Multiple ensembles for various prescribed
temperature changes
18
81
9 model runs
Sign of change varies by GCM
The challenge of summarising the results
The ensemble mean
But there are issues with the ensemble mean
The challenge of summarising the results
Number of models in agreement
Projected Changes in the Seasonal
Cycle of Average Runoff
Mekong Basin
&
Liard Basin
The Mekong
The Mekong
Changes in
sign vary by
GCM.
Magnitude
of changes
increase
with
temperature
The Liard
The Liard
Projected Changes in Global
Water Stress
Calculating stresses
• A region is stressed if water availability is
less than 1000m3/capita/year
• Therefore stress will vary acording to population
growth:
– Stress calculated for 3 populations scenarios
• SRES A1B
• SRES A2
• SRES B2
• Stresses calculated for the 2050s with different
prescribed warming (0.5-6.0ºC)
Global water resources stresses
HadCM3
Global water resources stresses
IPSL CM4
HadCM3
CCSR
MIROC32HI
Global water resources stresses
IPSL CM4
HadCM3
CCSR
MIROC32HI
Global water resources stresses
Global water resources stresses
Global water resources stresses
Global water resources stresses
Global water resources stresses
Global water resources stresses
Little uncertainty due to population change but much
due to GCM choice
Summary and Conclusions
• Use of the campus grid has reduced run
time from 21 days to 9 hours
• This allows a comprehensive investigation
of climate change impacts uncertainty
• Results demonstrate:
– GCM structure is a major source of uncertainty
– Sign and magnitude of runoff changes varies
across GCMs
– For water resources stresses, population
change uncertainty is relatively minor
Thank you for your time
Visit www.walker-institute.ac.uk