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Product information
23
April 2018
23°C growing season temperature average.
Above 24°C production levels drop signifi-
cantly (see
Graph 2
). If maize is droughted,
warming causes adverse effects from as
low as 16°C.
This information is useful to assess how
much time we have to adapt to what might
happen over the next ten to 20 years, and
suggests that if rainfall does not decrease,
the major maize growing regions have one
or two decades available to adapt to ongo-
ing warming. It will therefore be important
to build resilience in the short term to cli-
mate variability especially by improving our
ability to predict adverse climate events like
El Niño conditions, and retain moisture in
the soil to reduce vulnerability to short term
dry spells.
Continuing with his ‘silver lining’ message,
Prof Midgley noted South Africa is better off
than some competitors, e.g. the US climate
is ‘going crazy’. The melting of the Arctic
ice sheet is disturbing circulation patterns
around the North Pole, resulting in extreme
warming/cooling events which are already
affecting peoples’ lives. Prof Midgley also
said producers need to stay alert, because
new problems arise as temperatures warm,
e.g. fall army worm. Early warning systems
must be put in place and producers must be
equipped to manage such invasions.
What can be done about it?
Reduce GHG emissions
Capture emissions in the soil. The land we
manage has a role to play in carbon storage.
The ability to sequester carbon could be of
high value in the future.
Soil management
Halting soil degradation will gain soil car-
bon and have a wide array of other benefits.
Conservation agriculture has a role to play.
Prof Midgley suggested there may be a con-
flict between continuous pursuit of higher
yields and a conservation agriculture ap-
proach which may sacrifice yields but score
dramatically in terms of building resilience
and carbon sequestration.
Take home messages
Climate change is real.
South African grain producers have
time. Food security issues north of
borders which will result from climate
change impact, will present opportuni-
ties for South African producers.
The four building blocks of resilience
are:
Soil management
Pest management/monitoring
Cultivar selection/testing; new tech-
nology
Climate monitoring and prediction.
Producers need to:
Get informed about climate variability
and build resilience.
Call for better technology and predict-
ability over a ten-year period.
If government doesn’t help, it will be up
to us.
Further references
https://www.ipcc.ch/pdf/presentations/briefing-
bonn-2007-05/sectoral-impact-ecosystems.pdf
https://www.sanbi.org/biodiversity-science/state-
biodiversity/climate-change-and-bioadaptation-divi-
sion/ltas
Graph 1: Global average temperature as reported by NASA GISS. Temperatures are expressed in
relation to the average for the mid-2000s, and show significant warming since the 1970s.
Credit: NASA GISS
Graph 2: Observed effects of 1°C warming in the growing season for maize yield in sub-Saharan
Africa, based on hundreds of trials. Responses of both well-watered and droughted maize are shown.
The average growing season temperature is indicated roughly for Bothaville, showing that it will
take a few decades to exceed the temperature threshold for negative warming impacts at current
rates of warming.
Credit: After Lobell
et al
(2011)
Nature Climate Change
(1):42 - 45
Prof Guy Midgley of the Department Botany and Zoology at Stellenbosch University is an internationally acknowledged
expert in the field of biodiversity and global change science. He was a member of the Intergovernmental Panel on Climate
Change (IPCC) which shared the Nobel Peace Prize for compiling the 4th Global Climate Change Assessment of 2007. He
has been listed as one of only six internationally ‘highly cited researchers’ in South Africa by Thompson Reuters and led the
flagship Long Term Adaptation Scenarios (LTAS) research programme for the Department of Environmental Affairs between
2012 and 2015. Having grown up the son of a producer in the Western Cape, he identifies with the farming community with
insight into the challenges producers face, especially regarding extreme climate events and crop loss.