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Sifelani Tsiko
A new study by Desmond Manatsa, a climate science expert from Bindura University of Science Education shows that the rise in surface air temperatures in southern Africa over the past two decades may be due to the loss of upper atmospheric ozone over Antarctica (South Pole).This work was published in the journal Nature Geoscience.
The findings suggest that the closure of the Antarctic ozone hole could lead to a reduction in surface air temperatures in southern Africa.
This contradicts the current view by scientists on the surface air temperature warming over the sub-continent which is attributed to greenhouse gases.
The research team led by Manatsa who was working with colleagues from the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) used reanalysis data to compare the climate of southern Africa before and after the development of the Antarctic ozone hole.
They found that a shift in Southern Hemisphere circulation resulting from the development of the ozone hole coincided with the intensification of a low pressure system over southern Africa — which in turn, was associated with the flux of warm air from the lower latitudes to southern Africa.
Manatsa told the Herald from Japan that: “This is an interesting discovery because all along we were made to believe that the warming of the southern African subcontinent especially during our summer months was due to carbon dioxide emissions, which is generally known as global warming.
“Little did we know that the development of the ozone hole over the South Pole is actually involved in some complicated process which reversed the circulation surface air patterns over southern Africa during the summer months so that they predominantly come from the north hence warming our region.”
Manatsa is in Japan where he is reading for a PhD.
Asked to comment on the implications of this discovery on the scientific community and ordinary people of southern Africa at large, he said: “Well it is straight forward.
The projections of the climate change models, which I believe did not take into consideration this novel phenomenon, may not be advising us well on the real picture of the surface air temperature changes over southern Africa and their causes.
“However, this is not all doom for the sub-region. Many countries including Zimbabwe are now complying with the Montreal Protocol on cutting down on the usage of those substances (CFCs) which enhance the growth of the zone hole.
“As such we should be seeing the ozone hole eventually closing up and our summer temperatures will be restored to the previous comfortable levels.”
The ozone layer is a layer in Earth’s atmosphere which absorbs most of the UV radiation and contains relatively high concentrations of ozone (O3).
After the discovery of the ozone hole, the 1989 Montreal Protocol was signed by 196 countries to reduce global CFC production to protect the ozone hole.
This research study highlighted that from the recent Southern Hemisphere climate change driven by the ozone hole, the new trend could be deduced from climate model integrations.
It also pointed to the need to expand research to see the correlation of the ozone depletion of the North Pole and the climate changes in the Northern Hemisphere and similarly to those occurring in the South Pole.
Globally, southern African is one of the most vulnerable regions to the impacts of climate change.
Climate experts say current climate variability and vulnerability to extreme events such as floods and droughts is high.
They also say climate change has serious implications on the sub-continent’s water availability, land, biodiversity, something that could affect food security and development.
Already, the observed temperature changes for southern Africa are higher than the increases reported for other parts of the world and projections indicate a 3,4 degrees Celsius increase in annual temperature when comparing the period 1980 — 1999 with the period 2080–2099.
Climate experts say warming over the region is likely to be twice the global average.
Further projections indicate overall drying for southern Africa, with increased rainfall variability, a delay in onset of the rainy season with early cessation in many parts and an increase in rainfall intensity in some parts.
Key risks related to increased average temperature include heightened intensity and frequency of extreme weather events such as floods and droughts, more severe heat and water stress, rising sea levels, landslides and soil erosion.
Online Reporter