Francois Engelbrecht Christien Engelbrecht

1. Klimaatsverandering oor Suid-Afrika – van die
volgende paar dekades tot die einde van die
eeu
Francois Engelbrecht1 and Christien Engelbrecht2
1. WNNR Natuurlike Hulpbronne en die Omgewing
2. Landbou Navorsingsraad – Instituut vir Grond, Klimaat en Water

8. Summer-season rainfall
anomalies over the Free
State and North West
provinces (x-axis) and
Niño 3.4 sea-surface
temperature anomalies
(y-axis) for 1901-2015.
Rainfall anomalies from
CRU and GCPC are for
DJF. SST anomalies
from AMIPII are for
OND.
All anomalies were
calculated with respect
to the 1971-2000
baseline period.
CSIR-ACCESS
2015/16 1997/98
2016/17

9. 2015: the warmest year on record!

10. The 2015/16 El Niño (image from NOAA):
One of the strongest events ever recorded. Strong El Niño’s are
projected to double in frequency towards the end of 21st century under
low mitigation

11. In September 2016, the
entire summer rainfall
region was in a state of
mild drought, or worse.
The Free State, northern
KwaZulu-Natal and
eastern Mpumalanga
was in a state of severe
drought.
How will climate change
impact on the attributes
of drought in the mega-
dam region of SA?
Drought in southern Africa
A dust storm rolls over the plains of
the Free State in December 2015.

12. Drought in southern Africa
Depleted grazing in Kruger Park in
September 2016.
By September 2016,
The entire summer
rainfall region of
South Africa was in
a state of mild
drought, or worse.
The Free State,
northern KwaZulu-
Natal and eastern
Mpumalanga was in
a state of severe
drought .

13. 2015 warmest year ever recorded globally (+ 1 ºC); summer of 2015/16
the warmest ever recorded over southern Africa (+ 2 ºC)
2015/16 anomalies relative to 2006/7 to 2014/15 climate; ARC station data;
Engelbrecht C et al. (2017) in preparation

14. © CSIR 2007 www.csir.co.za
Observed
trends in
annual-average
temperatures
over Africa
1961-2010
(Engelbrect et
al., 2015; ERL
10: 085004)
Garland et al.,
2015; Int J of
Env Res and
Public Health

15. © CSIR 2007 www.csir.co.za
The first African-
based earth system
model VRESM is
under development
through a CSIR-
CSIRO
collaboration
Global climate modelling at the CSIR
NRE
• NWP and RCM capacity build around the conformal-cubic
atmospheric model (CCAM) of the CSIRO
• A cube-based global model; semi-Lagrangian semi-implicit
solution of the primitive equations
• Includes a wide range of physical parameterizations
• Developed by the CSIRO Marine and Atmospheric Research
(McGregor, 2005)
• Runs in quasi-uniform or in stretched grid mode
• Multi-scale climate modelling.

16. © CSIR 2007 www.csir.co.za
Regional climate modelling over Africa using
CCAM CCAM applied in
stretched-grid mode
Modest stretching
provides a resolution of
about 8 km over southern
Africa
Development of Africa’s
first coupled climate
model is in progress
Development targets the
main unresolved climate
change questions for
Africa and the SH in
support of climate
services
A C192 stretched-grid with resolution about 8
km over southern Africa

17. • Computer clusters available to the
project include the CHPC in South
Africa (24 000 + CPUs – VRESM
allocation is currently ~ 3 000 000 core
hours per quarter);
• The VRESM design has achieved
some comparable resolution and
computing times with less than 10% of
the cores required by some more
traditional coupling approaches.
• CSIR NRE data servers and CHPC
VRESM allocated space currently
amounts to 600 TB
HPC and code-
scalability
CCAM-TOM (CSIRO) scaling with 35
atmosphere levels and 30 ocean
levels, suggesting excellent
simulation speed for computing
resources
0.1
1
10
100
100 1000 10000
Simulationyearsperday
Number of cores
CCAM scaling 35L 30OC192 (50 km) C384 (26 km) C768 (13 km)

18. From CSIRO: Martin Dix
Projected temp anomalies for 2081-
2100 relative to pre-industrial
conditions (0-degree world)
AR5 WG1 estimations relative to
1986-2005 were adjusted with a 0.6
°C factor
Only RCP 2.6 can safely keep us well
below the Cancun agreed 2 °C (Long
Term Global Goal), whilst the world is
currently between A2 and RCP 8.5
Emission Scenarios and Representative Concentration
Pathways
Scenario Temp anomalies relative to pre-
industrial (adapted from AR5)
RCP 2.6 0.9 to 2.3
RCP 4.5 1.7 to 3.2
RCP 6 2.0 to 3.7
RCP 8.5 3.2 to 5.4
2.6

19. © CSIR 2007 www.csir.co.za
CSIRO-CSIR
collaboration: 0.5°
resolution global climate
change downscalings for
CORDEX using CCAM
Downscaling various
CMIP5/AR5 CGCMs for
different RCPs
Martin Dix, CSIRO

20. © CSIR 2007 www.csir.co.za
CSIRO-CSIR
collaboration: 0.5°
resolution global climate
change downscalings for
CORDEX using CCAM
Downscaling various
CMIP5/AR5 CGCMs for
different RCPs
Martin Dix, CSIRO

21. © CSIR 2007 www.csir.co.za
More uncertainty
surrounds the
projected rainfall
futures of Africa
under climate change
Southern Africa is
projected to become
generally drier by
most models, whilst
East Africa is
projected to become
generally wetter – an
El Niño signal!
Figure: Projected
changes in rainfall
(mm) (left) and the
average value of the
Keetch-Byram
drought index (right)
over Africa for 2071-
2100 relative to 1961-
1990
Engelbrecht et al.,
2015; ERL 10: 085004

22. Projections of changing
annual average
temperature (degrees
C) over southern Africa
for the period 2046-
2065 relative to 1961-
1990
CSIR-CHPC

23. Projections of changing
annual average
temperature (degrees
C) over southern Africa
for the period 2070-
2099 relative to 1961-
1990
CSIR-CHPC

24. Projections of changing
annual rainfall over
southern Africa for the
period 2046-2065
relative to 1961-1990
CSIR-CHPC

25. Projections of changing
annual rainfall over
southern Africa for the
period 2070-2099
relative to 1961-1990
CSIR-CHPC

26. Climate Change and
the seasonal cycle
• Regional climate models realistically represent
the present-day seasonal cycle in rainfall and
circulation across the African continent
(Engelbrecht et al., 2009)
• Model projections of future climate change are
generally not indicative of significant changes
in the seasonal cycle of rainfall and
temperature over Africa, however, significant
changes are projected in the amplitude of
seasonal extrema
• The most interesting changes are to be found
on the application side, e.g. a changing
seasonal cycle in energy demand and wild
fires (e.g. Engelbrecht et al., 2015; ERL 10:
085004)
• Figure shows the present-day (black) and end-
of-the-century range of projected changes in
the seasonal cycle of the Keetch-Byran
drought index over southern and tropical Africa
(Engelbrecht et al., 2015; ERL 10: 085004)

27. © CSIR 2007 www.csir.co.za
Projected climate
change futures for
southern Africa: an
“El Niño” signal?
The Free State and
North West province are
projected to drift into a
temperature climate
regime never observed in
recorded history
Temperature increases of
5-9 degrees C are
plausible by the 2081-
2100 period
Significant rainfall
reductions are projected
3ºCworld1.5ºC
world

28. © CSIR 2007 www.csir.co.za
Main messages related to the climate-change signal
A robust pattern of drastic temperature rise is projected for southern Africa
under the RCP8.5 and A2 scenarios – an actionable climate change signal.
Temperature increases are projected to range between 4 and 7 °C over
the interior by the end of the century – increases larger than 6 °C are
plausible over much of semi-arid southern Africa under low mitigation.
Temperature increases may plausibly reach 3-4 °C by the 2040s
Drastic increases in the number of high fire-danger days, very hot days and
heat-wave days are projected to across the African continent under low
mitigation.
The southern African region is likely to become generally drier. Over
northeastern South Africa, Mozambique and Zimbabwe an increase in
extreme rainfall events is plausible.
Multi-year El Niño type droughts may plausibly occur
from the mid-century (2036-2065 (onwards)