Risks in the built
environment in a changing
world
Bob Scholes
CSIR Natural Resources and Environment
5Feb 2013 SAIA workshop
Question 1: What aspects of the built environment
present risks that could be collaboratively addressed?
•
•
•
•
Coastal Flooding due to sea level rise and storms
Inland flooding due to increased storm intensity
Fires, especially megafires due to climate change
Drought, particularly in western southern Africa
Sea level rise
Rahmstorf 2007
Science 316:368
Historical
sources
Tide gauges
Church et al 2004
Satellites
Cazenave & Llovel 2010 Contemporary Sea Level Rise. Ann Rev Marine Sci 2, 145-173
IPCC AR4
Sea level rise will effect even South Africa
Sea level rise, plus changes in storm intensity,
combined with tidal dynamics and increased coastal
development.
CSIR has developed a wave climate model for the
entire coastline. Detailed analyses for specific
locations require high-resolution bathymetry and
altimetry
Projected change in
extreme rain events over
South Africa
(>20 mm in 24 hours over an area of
50 km x 50 km)
A general increase in the
frequency of extreme
rainfall events, especially
the highveld
Slide: Francois Engelbrecht, CSIR
© CSIR 2007
www.csir.co.za
Question 2: Practical steps, by whom…
coastal flooding
Body
Topic
Action
Surveyor General, SA Navy,
private firms
Near coast high
resolution altimetry and
bathymetry
Survey areas of
infrastructure
CSIR
Surge mapping
Apply models to map
impact areas
Local authorities
Building permits
Do not give permits in at
risk areas
Insurance industry
Insurance premiums
Structure premiums to
reflect changing risk
Coastal management
Coastal protection
Dune, beach and estuary
management
Question 2: Practical steps … inland flooding
Body
Topic
Action
CSIR
Downscaled climate
Models with 8 km
resolution for 21st century
Hydrologists: universitis and Flood return statistics
consultancies
New tables and maps for
20 and 100 yr floods
DWA
Catchment management Restoration, flood control
structures, management
of flows
National Disaster
Management, DWA and
SAWS
Real-time warning
Models and observaion
system with alerts
Planning authorities
Reduction in exposure
Control development in
flood zone
Question 2 cont: Practical steps…fire
Body
Topic
Action
CSIR
Advanced Fire
Information System
Realtime warning
SAWS
Fire danger index
24 and 48 hour forecasts
Working on Fire
Fire avoidance
Fuel reduction, firebreaks
National Disaster
Management
Rapid intervention
Response teams for
megafires
Planning authorities
Reduction in exposure
Control buiding in fireprone areas
Fire Protection associations
Avoidance and response
Firebreaks, local response
teams
Question 2 cont: Practical steps…drought
Body
Topic
Action
CSIR, UCT-CESAG
Downscaled aridity
projections
Drought probability maps
for future climates
ARC, SANSA, SAWS
Early warning, affected area
verification
Greenness and wetness
anomalies
DAFF, Provincial
authorities, Farmers
organisations
Non-financial insurance avoids Forage and livestock
damage rather than
banking
compensating for it
Rapid offtake schemes
Insurance industry
Financial insurance for
farmers taking appropriate
adaptation steps
Re-assess risks as they
change through the
century
End of brief presentation
bscholes@csir.co.za
Human vs Natural Causes
Evidence of a changing world
Southern Africa is
projected to warm at a
higher rate than the
global average
2071-2100 vs 1961-1990
CCAM ensemble-average projected change in the
Annual frequency of very hot days
(>35C, 2071-2100 vs 1961-1990)
..but rainfall
futures remain
uncertain for our
region
Ensemble average
Agriculture
Climate change effects are negative
overall
Blignaut et al
Dube & Scholes 2011
Scholes livestock: substantial
decrease in production
Rising temperatures are
the key driver, even once rain and
CO2 are factored in
But,
1. Large yield gap in Africa
(5x)
2. Substantial potential for
crop area expansion in in
sub-humid Africa (2x)