The Sunday Mail
Samuel Kusangaya
Climate change is now widely regarded as a key global challenge.
Observations from long-term global datasets suggest that natural resources such as land and water are increasingly becoming vulnerable, and climate change is likely to worsen the levels of vulnerability.
This is especially relevant in Southern Africa, where climate change interact with other external factors which, in turn, have serious implications for people, ecosystems, biodiversity and economies.
Climate change affects socio-economic development, with the effects being more enhanced when combined with other key global challenges such as food security and population growth.
Climate change is likely to result in higher sea levels, intense storms and heavy rainfall events, as well as frequent drought occurrences. A number of these climate hazards are already occurring and impacting on human settlements, causing loss of life, social disruption and economic hardships.
Such hardships are heavily felt by the poor, who have limited options for dealing with these climate-induced hazards.
However, uncertainties still remain regarding the rate of climate change and the scale and distribution of the impacts over Southern Africa. Nevertheless, the persistence of the observed changes in climate over the past century like the increase in the occurrence, magnitude and severity of extreme events implies amplified impacts on the very poor in Southern Africa.
Southern Africa is inherently characterised by a highly variable climate both, spatially and temporally.
Climatic regions range from semi-tropical (Angola, Malawi, Mozambique and Madagascar), semi-arid (South Africa, Zimbabwe and Botswana) to arid (Namibia).
Apart from the highly variable climate, reasons for the high vulnerability across the region include the highly agro-based economies (rain fed and irrigated), severe water challenges (quantity, quality and distribution) and high exposure and low adaptive capacity, particularly among rural communities.
Occurrences
Studies from Southern Africa have shown that extreme events (for example droughts and floods) are increasing in frequency and magnitude.
These extreme events are heavily influenced by El Niño-Southern Oscillations, which are becoming more intense as a result of climate change.
For example, in Southern Africa, the frequency of droughts is projected to increase and will most likely increase the frequency of extreme low flows and low storage episodes.
These will inevitably affect aquatic ecosystems, water supply, irrigation, leisure, and hydro power generation.
Studies show that Africa has the second highest number of extreme events after Asia.
A significant number of these — floods and droughts — are occurring in Southern Africa.
For Southern African countries, it can be seen that: (a) the occurrence of natural disasters in the last two decades (1991-2000 and 2001-2010) is by far higher than for the previous decades, with the 2001-2010 decade having the highest occurrences, and (b) the occurrence of these disasters has been increasing at an exponential rate.
The number of natural disasters in the last decade is in most cases equivalent to the total number of disasters in the previous three decades.
It is, therefore, concluded that there is an increasing trend of extreme events in Southern Africa.
Floods, droughts and tropical cyclones
Extreme flooding events have been and continue to be one of the most important natural hazards responsible for deaths and economic losses in Southern Africa.
Experts say extreme floods result in direct destructive effects during the time of the event, and they also may be followed by a related chain of indirect calamities such as famines and disease epidemics that produce additional damages and suffering.
To date, Southern Africa has been characterised by extremely devastating events.
Examples include recurring floods in Mozambique and droughts which have caused food insecurity, increased incidences of cholera and malaria, loss of shelter and loss of life as happened in the 2000 – 2001 Cyclone Eline and 2019 Cyclone Idai-induced floods, which affected Mozambique, Malawi and Zimbabwe.
Additionally, studies have shown that tropical cyclone activity in Southern Africa has increased in frequency and intensity in recent years, causing massive damage and loss of life in Mozambique, Zimbabwe, Zambia, Swaziland, South Africa, Madagascar and Mauritius.
Six warmest years on record for Zimbabwe have occurred since 1987, with corresponding increased frequency of droughts in southern Africa since 1990 (90/91, 91/92, 92/93, 93/94, 94/95, 97/98, 01/02, 02/03, 04/05, 06/07) causing massive drops in crop yields in Zimbabwe, Malawi and Zambia.
These observations ultimately signify a significant shift of climate variables from the recent past. Although the occurrence of droughts and floods has been fluctuating over the past decades, the two natural hazards have been on an increasing trend.
Increasing drought trends are noticeable in Lesotho, Malawi, Mozambique, South Africa and Madagascar, while floods tend to be dominant in Angola, Botswana, Malawi, Mozambique, South Africa, Zimbabwe and Zambia.
The increasing cases of recorded epidemics are also closely related to the increasing occurrence of floods due to increased cyclone activity as in the case of Mozambique, Zimbabwe, Lesotho and Malawi.
Recently, Southern Africa has been experiencing heat waves and extensive wildfires, aphenomena that had never been recorded before.
The upsurge in heat waves and wildfires is attributable to increasing temperatures.
Thus, overall, the occurrence of these multiple natural disasters is likely to further constrain the adaptive capacity of the region.
Causes
Several factors operating at different spatial and temporal scales have led to various extreme events in Southern Africa.
Some of these extreme events are attributed to or exacerbated by climate change.
While there is unequivocal evidence that the climate is changing, there are divergent views on the causes and attributed consequences of the obtaining climate change.
For example, whilst some areas are experiencing an increasing number of frequent dry spells, others are experiencing the opposite.
In other words, they are experiencing an increase in consecutive wet spells that span a relatively long period of time.
So far, however, a number of studies from Southern Africa have shown that extreme events are increasing in frequency and magnitude. For example, the El Niño-Southern Oscillation effect has continued to strengthen in recent decades, resulting in more floods and droughts.
Most experts now attribute climate change to the intensification of the El Niño-Southern Oscillations.
On the other hand, the frequency of droughts is projected to increase and will most likely lead to an increase in the frequency of extreme low flows and low storage episodes.
Extreme low flows and low storage episodes inevitably affect aquatic ecosystems, water supply, irrigation, leisure, and hydro power generation.
Knowledge about the characteristics of extreme events is valuable for planning and designing infrastructure.
Both urban and rural areas contain many types of hydraulic engineering structures such as dams, water distribution networks, water collection networks, sewage collection networks and storm water management, which need to be designed to accommodate peak flows of a certain magnitude in order to function safely at a given level of risk.
Should the structures fail, especially where human settlement is dense, there are potential societal, economic and environmental consequences.
However, for Southern Africa, knowledge about magnitudes and recurrence intervals of extreme events is still hampered by lack of long-term datasets.
Consequently, this limits the ability to adequately evaluate potential magnitudes and recurrence frequencies of extreme events.
Vulnerability
Southern Africa is one of the most vulnerable regions to climate change as a result of increased exposure to climate extremes and limited adaptation capacity.
The lack of long-term weather data is one of the major constraints in assessing risk from climate change.
Most parts of the Southern Africa region are not adequately covered by networks of hydro-meteorological stations and data collected is not readily accessible to users.
Thus, the combination of inadequate understanding of atmospheric and biospheric processes and lack of hydro-meteorological data explain the limited knowledge about climate variability and climate change and the potential impacts thereof in the region, resulting in ineffective responses, especially at a local scale.
Consequently, this results in Southern Africa being more vulnerable and ill-equipped to cope with the effects of climate change. Climate change is expected to worsen the current stress on natural resources resulting from population growth, economic factors and land-use changes.
The Southern African region is regarded as one of the most vulnerable regions due to lack of financial, institutional and technological capacity, low adaptive capacity, endemic poverty, low technology uptake and heavy dependence on rain-fed agriculture.
Moreover, the climate of Southern Africa, which is predominantly arid to semi-arid, further increases the exposure of the region to climate change extremes.
Thus, knowledge of impacts of climate change and extreme events is critical for the development of adaptive strategies for the region. For Southern Africa, universities and research centres should therefore increase their focus on improving the scientific capacity, research financing, research infrastructure, technological use and information dissemination.
Mr Samuel Kusangaya is a Geographic Information Systems (GIS) and Remote Sensing expert with interest in geo-information science applications in climate change modelling, vegetation monitoring, hydrology and water resources management and database management.
