Projecting future climate change over Africa

The African continent is likely to experience a wide range of impacts from future climate change, with large parts of subtropical Africa projected to become generally drier and significantly warmer during the 21st century. This may threaten the sustainability of agriculture and livestock farming, biodiversity and water security. It is likely to alter energy demand and increase the prevalence of natural disasters such as flooding, droughts and fires. The CSIR helps find workable ideas that help us to understand and plan for what may be the greatest problem ever faced by humanity. The organisation has developed extensive capacity in regional climate-change projection and the study of climate change impacts to inform southern Africa and Africa’s efforts to mitigate and prepare for these changes.

The concentration of carbon dioxide (CO2) in the earth’s atmosphere has increased by about 40% since the industrial revolution and is the main cause of global warming and climate change. CO2 concentrations are continuing to rise, mainly driven by human activities, and in particular the burning of fossil fuels for energy.

Increased greenhouse gas concentrations have already caused global temperatures to rise and climate experts are warning that further global warming may take place at an accelerated rate. A concerted international effort is needed to mitigate the magnitude of the change, but countries will also need to consider adaptation measures at a regional level to prepare for changes that are inevitable.

This is particularly challenging in southern Africa, a region faced with economic and developmental challenges and where temperatures over some regions will rise at about twice the global rate of temperature increase.

Dr Francois Engelbrecht – who leads climate studies, modelling and environmental health research at the CSIR – says that South Africa is particularly vulnerable to climate change. “Even if global efforts to curb CO2 emissions successfully limit temperature increases during the 21st century to 2 ⁰С relative to pre-industrial times as climate scientists hope, southern Africa could see an increase of up to 4 ⁰С over the interior regions.”

Research

Global climate models have become the main tool to project future climate change. However, their projections are of too coarse horizontal resolution to develop climate change projections at a regional or municipal scale.

The CSIR’s climate modellers, supported by the Centre for High Performance Computing, are therefore developing downscaled climate projections, which are being used widely to project the local impact of climate change on South Africa and Africa. In agriculture, research has shown that a 4 ⁰С temperature increase can significantly reduce maize harvests over southern and East Africa. “In a worst-case scenario where global climate mitigation fails, temperature increases of 6 to 8 ⁰С are plausible over parts of Africa. International crop modelling studies show that no current maize varieties can withstand such drastic temperature increases, and failure of the maize crop in southern and East Africa may reach drastic proportions under such a scenario,” says Engelbrecht.

Researchers from the University of Pretoria have also used the CSIR’s models to project the future of potato farming in South Africa. They have found that the increase in CO2 levels might boost potato harvests, but this benefit will be lost if there is not enough water for irrigation due to projected decreases in rainfall.

Tomato farmers in the north-eastern parts of South Africa are reporting that is has already become too hot to grow tomatoes in mid-summer in parts of Limpopo. They are foreseeing a shift of tomato production, at least to some extent, to farms in cooler Gauteng where winter frost is likely to occur less frequently under climate change.

According to the CSIR’s Dr Emma Archer-Van Garderen – who has studied the impact of climate change on cattle farming – future increased temperatures can cause heat stress which can influence feed intake, fertility, weight gain and mortality. Different breeds have different heat thresholds and farmers might have to look at more resilient, locally adapted breeds to maintain production.

Climate change could also induce bush encroachment as plant species differ in their capacity to benefit from CO2. This in turn could have a negative impact on the natural habitat of large herbivores that survive in the grasslands and savannah regions of South Africa. Warmer and drier temperatures will also impact on many other aspects of the country’s biodiversity. Fynbos – which evolved over thousands of years in moderate temperatures and wet winters – may not be able to thrive under drier winters that are also significantly warmer, while small bird species are highly vulnerable to extreme heat conditions.

CSIR research on the climate future of Africa is also starting to find increasing impact in industry, says Engelbrecht. Eskom currently uses the CSIR’s downscaled climate models to inform its adaptation strategies in terms of the effects of high-impact climate events on Eskom infrastructure and household demand for energy.

CSIR researchers project that Africa may experience more extreme weather events under climate change, such as intense thunderstorms, large-scale flooding, heat waves and drought. An increase in tropical storms and cyclones that reach land are also projected for the northern parts of neighbouring Mozambique. Many sectors, including the insurance industry, are likely to be increasingly affected by the costs associated with high-impact climate events.

The CSIR research on climate change also informs national policy-making. Recently, the CSIR climate change projections formed an integral part of the Long-Term Adaptation Scenario Project of the Department of Environmental Affairs (DEA) and related CSIR research informs the position of the DEA on aspects of the climate negotiations of the United Nations Framework Convention on Climate Change (UNFCC).

Climate change projections are continuously being refined and extended. Engelbrecht points out that, going forward, the CSIR’s climate change researchers will contribute to international climate change projection initiatives, such as the Coordinated Regional Downscaling Experiment and Coupled Model Inter-comparison Project Phase 6 of the World Climate Research Programme. CSIR researchers will also study the implications of the UNFCC climate negotiations to inform suitable adaptation and mitigation strategies for Africa.

04
Dec
2014

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