Climate Change Science of Africa

Friday, October 30, 2015

Evidence stretching back 40,000 years shows that global warming will increase drying in a region of East Africa where drought already causes humanitarian crises

by Alex Kirby, Climate News Network, October 10, 2015

LONDON – One of Africa’s most volatile regions has become increasingly dry over the last century and faces a future of rising tension if this trend continues, US researchers say.

They say the rate of drying in the Horn of Africa is both unusual in the context of the last 2,000 years and in step with human-influenced warming. And they think the drying will continue as the region warms.

“Right now, aid groups are expecting a wetter, greener future for the Horn of Africa, but our findings show that the exact opposite is occurring,” says one of the study’s co-authors, Peter deMenocal, who heads the Center for Climate and Life at Columbia University’s Lamont-Doherty Earth Observatory.

“The region is drying, and will continue to do so with rising carbon emissions.” The study, published in the journal Science Advances, was based on evidence stretching back for 40,000 years.

Sediment core

The researchers used a sediment core they had extracted from the Gulf of Aden to infer past changes in temperature and aridity. After matching the core’s record with 20th-century observations, they concluded that drying is likely to continue across Somalia, Djibouti and Ethiopia.

That contradicts other models, which have suggested that future warming might bring rainier weather patterns that could benefit East Africa.

“What we see in the paleoclimate record from the last 2,000 years is evidence that the Horn of Africa is drier when there are warm conditions on Earth, and wetter when it is colder,” says lead author Jessica Tierney, associate professor of geosciences at the University of Arizona.

Global-scale models used to predict future changes as the climate warms suggest that the region should become wetter, primarily during the “short rains” season from September to November.

However, the new study suggests that those gains may be offset by declining rainfall during the “long rains” season from March to May, on which the region’s rain-fed agriculture relies.

The authors say the region has been racked with political instability and violence as it has dried. The Horn of Africa has suffered droughts every few years in recent decades − creating humanitarian crises as famine and violence spread.

In Somalia, as the political situation deteriorated amid the droughts of the 1980s and 1990s, hundreds of thousands of refugees fled the country, and pirates began raiding ships off the coast.

The 40,000-year-old sediment core has already yielded insights into Africa’s climate. In 2013, Tierney and deMenocal showed that the Sahara, which once used to burst into verdant life with regular rainfall, suddenly dried out over a century or two, during a warm period about 5,000 years ago – not more gradually, as many researchers had thought.

Their work provided evidence that climate shifts can happen quite suddenly, even if the forces driving them are gradual.

This latest study uses isotopes from leaf waxes found in the sediment sample to compare rates of drying over the past 2,000 years.

Plants reflect the environment that sustains them. When the climate is drier, leaf waxes are more enriched with deuterium, or heavy hydrogen isotopes, while leaf waxes from wetter climates reflect the more abundant rainfall through the presence of the normal hydrogen isotopes.

The researchers found an increasing shift toward heavy hydrogen in the last century as the climate − which had experienced a wet period during the Little Ice Age (1450-1850 AD) − dried out.

Climate modelling

Their findings suggest that climate modelling, frequently done at a global scale, would benefit from region-specific studies with higher-resolution results in high-impact areas such as the Horn of Africa

Tierney says: “If we can simulate rainfall in these arid tropical and subtropical regions better, we can understand the future impact of climate change.”

The development agency Oxfam says Ethiopia is facing a major emergency, with 4.5 million people needing food aid because of successive poor rains this year.

Oxfam’s representative in Ethiopia describes the situation − attributed to the El Niño periodic climate phenomenon in the Pacific − as “the start of a major emergency, which is expected to be serious and long.”

Meanwhile, parts of West Africa are suffering from the aftermath of severe floods − also attributed to El Niño − that have ruined crops and destroyed homes in Burkina Faso and Niger. 

Monday, September 7, 2015

Impact of climate change on staple food crop production in Nigeria, Climatic Change, September 2015; doi: 10.1007/s10584-015-1428-9

Climatic Change, 132(2) (September 2015) 321-336; doi: 10.1007/s10584-015-1428-9

Impact of climate change on staple food crop production in Nigeria

  • Valentina Mereu
  • Gianluca Carboni
  • Andrea Gallo
  • Raffaello Cervigni
  •  and Donatella Spano

Abstract


Climate change impact on the agricultural sector is expected to be significant and extensive in Sub-Saharan Africa, where projected increase in temperature and changes in precipitation patterns could determine sensible reductions in crop yields and concerns for food security achievement. This study presents a multi-model approach to analysing climate change impacts and associated risks for staple food crops in Nigeria. Previous attempts to evaluate climate change impacts in Nigeria had mainly focused on a reduced number of crops, with analysis limited to single experimental fields or specific areas, and in many cases considering only a limited number of climate models. In this work, crop simulation models implemented in the DSSAT-CSM software were used to evaluate climate change impacts on crop production in different Agro-Ecological Zones, considering multiple combinations of soils and climate conditions, varieties and crop management. The climate impact assessment was made using an ensemble of future climate projections, to include uncertainty related to climate projections. Even if precipitations could increase in most parts of Nigeria, this is not likely to offset the crop yield reduction due to the increase in temperatures, particularly over the medium-term period (2050), with yield decreases projected especially for cereals. The short-term effects are more uncertain and yields for cassava and millet might actually increase by 2020. Moreover, yield reductions are only partially mitigated by the direct effect of increased CO2 atmospheric concentrations enhancing crop yields. In both periods and for all crops, there is a higher risk that crop yields may fall below the actual risk threshold.

http://link.springer.com/article/10.1007/s10584-015-1428-9


Monday, May 5, 2014

NASA Finds Drought May Take Toll on Congo Rainforest

A view of the entire African rainforest area (green)A View of the entire African rainforest area (green) transitions into a view of the region included in the Nature study, primarily in the Congo forest (mostly brown). The study area represents intact areas in the Congo rainforest where satellite data are high quality. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio
› Larger image


from NASA's Jet Propulsion Laboratory, April 23, 2014
A new analysis of NASA satellite data shows Africa's Congo rainforest, the second-largest tropical rainforest in the world, has undergone a large-scale decline in greenness over the past decade.
The study, led by Liming Zhou of University at Albany, State University of New York, shows between 2000 and 2012 the decline affected an increasing amount of forest area and intensified. The research, published Wednesday in Nature, is one of the most comprehensive observational studies to explore the effects of long-term drought on the Congo rainforest using several independent satellite sensors.
"It's important to understand these changes because most climate models predict tropical forests may be under stress due to increasing severe water shortages in a warmer and drier 21st century climate," Zhou said.
Scientists use the satellite-derived "greenness" of forest regions as one indicator of a forest's health. While this study looks specifically at the impact of a persistent drought in the Congo region since 2000, researchers say that a continued drying trend might alter the composition and structure of the Congo rainforest, affecting its biodiversity and carbon storage.
Previous research used satellite-based measurements of vegetation greenness to investigate changes in the Amazon rainforest, notably the effects of severe short-term droughts in 2005 and 2010. Until now, little attention has been paid to African rainforests, where ground measurements are even sparser than in the Amazon and where droughts are less severe but last longer.
To clarify the impact of long-term drought on the Congo rainforest, Zhou and colleagues set out to see whether they could detect a trend in a satellite measure of vegetation greenness called the Enhanced Vegetation Index. This measure is developed from data produced by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Terra satellite. The scientists focused their analysis on intact, forested regions in the Congo Basin during the months of April, May and June each year - the first of the area's two peak rainy and growing seasons each year.
The study found a gradually decreasing trend in Congo rainforest greenness. The decrease, sometimes referred to as "browning," suggests a slow adjustment to the long-term drying trend. This is in contrast to the more immediate response seen in the Amazon, such as large-scale tree mortality, brought about by more episodic drought events.
The browning of the forest canopy is consistent with observed decreases in the amount of water available to plants, whether that is in the form of rainfall, water stored in the ground, water in near-surface soils, or water within the vegetation.
These changes in available water were detected in part with NASA satellites including the NASA/JAXA Tropical Rainfall Measuring Mission, NASA's Quick Scatterometer (QuikScat), and NASA's Gravity Recovery and Climate Experiment, a joint mission with the German Aerospace Center. The latter two missions are managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif.
"Combining measurements from different sensors has given us more confidence in the results of the MODIS data and provided us with insights into the environmental and physiological mechanisms of the browning observed by the MODIS data," said co-author Sassan Saatchi of JPL.
Climate factors known to affect vegetation growth were also in line with the observed browning. Land surface temperatures, for example, were observed to increase over most of the study area. Decreased cloudiness allowed more solar radiation to reach the plants, which typically promotes photosynthesis, but in this case it likely posed an extra stress on the plants from the resulting depletion of soil moisture.
"Forests of the Congo Basin are known to be resilient to moderate climate change because they have been exposed to dry conditions in the past few hundred years," Saatchi said. "However, the recent climate anomalies as a result of climate change and warming of the Atlantic Ocean have created severe droughts in the tropics, causing major impacts on forests."
How the changes affect individual plant species in the area remains to be seen. For example, drier conditions may favor deciduous trees at the expense of evergreen trees.
"Our assessment is a step toward an improved understanding of how African rainforests respond to increasing drought," Zhou said. "We need to consider the complex range of processes affecting different tropical rainforest species before we can fully assess the future resilience of tropical forests."
The other authors for this research include Yuhong Tian at I.M. Systems Group, Inc. at the Center for Satellite Applications and Research, the science arm of National Oceanic and Atmospheric Administration's Satellite and Information Service, College Park, Md.; Ranga Myneni at Boston University in Massachusetts; Philippe Ciais at Laboratoire des Sciences du Climat et de l'Environnement, Gif sur Yvette Cedex, France; Yi Y. Liu at University of New South Wales, Australia; Shilong Piao at Peking University, China; Haishan Chen at Nanjing University of Information Science and Technology, China; Eric Vermote of NASA's Goddard Space Flight Center, Greenbelt, Md.; and Conghe Song and Taehee Hwang at the University of North Carolina at Chapel Hill.
NASA monitors Earth's vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

Friday, April 25, 2014

Congo forest feels bigger climate impact

by Tim Radford, Climate News Network, April 25, 2014

Researchers say there is increasing evidence that climate change is among the factors causing serious damage to the rainforest of the Congo basin.

LONDON, 25 April - The Congo – one of the world’s greatest rainforests – is getting steadily less green. The slow change in colour during this century, recorded by a series of US satellites, has been matched by a rise in temperature and lower precipitation. And, researchers think, it could reflect a forest’s response to climate change.

Scientists from Australia, China, the US and France report in the journal Nature that they examined optical, thermal, microwave and gravity data collected by orbiting sensors between 2000 and 2012.

They concentrated on intact forested regions during the months of April, May and June each year, which span the peaks of growth and rainfall. They detected an intensification in the forest’s decline. This decline was consistent with lower rainfall, poorer water storage below the canopy and a gradual change in the composition of species.

“It is important to understand these changes because most climate models predict tropical forests may be under stress due to increasing severe water shortages in a warmer and drier 21st century climate,” said Liming Zhou, of Albany State University of New York. But other factors could accelerate this “browning” of one of the world’s greatest rainforests.

Half as hot again

A team from the Catholic University of Louvain in Belgium - also known in Belgium’s other language as KU Leuven - predicts in the Journal of Climate that explosive population growth and inefficient agricultural practices are likely to make things a great deal hotter for the region and a great deal worse for the rainforest.

By 2050, according to their computer models, Central Africa will be on average 1.4 °C hotter than it is today just because of greenhouse gas emissions. And the steady destruction of the forest will add an extra 0.7 °C to that figure.

Temperature increases on such a scale will harm plant and animal species and even bring about some extinction. Where the forests have been cleared, there will be increased levels of evaporation, and consequent rises in temperature.

Across the Atlantic, things also look bleak for the Amazon rainforest. Paulo Brando of the Amazon Environmental Research Institute in Brazil and colleagues from the US report in the Proceedings of the National Academy of Sciences that the piecemeal clearing of the rainforest, along with drought, has begun to create “tinderbox” conditions  and an ever more destructive cycle of burning.

Non-average menace

Over the course of 8 years, in one of the longest-running experiments of its kind, the researchers burned 50-hectare plots of forest in the south-eastern Amazon, a region vulnerable to climate change. They compared the tree deaths each year to measure the impact of drought on fire intensity.

“Drought causes more intense and widespread fires,” said Dr Brando. “Four times more adult trees were killed by fire during a drought year, which means that there was also more carbon dioxide released into the atmosphere, more tree species loss and a greater likelihood of grasses invading the forest.”

This research, too, was backed up by satellite observation. In 2007, a year of drought, fires in south-east Amazonia burned 10 times more forest than in an average year - an area equivalent to a million soccer fields, according to Douglas Morton of the US space agency NASA, a co-author.

Climate change is expected to bring shorter, more intense rainy seasons and longer dry seasons in the region. Michael Coe of Woods Hole Research Center, another author, said “We tend to think only about average conditions, but it is the non-average conditions we have to worry about.” 

Tuesday, January 28, 2014

Vulnerable to climate change, Cameroon tackles the problem head-on

Though particularly vulnerable to climate change, students in Cameroon are developing innovative technological solutions

by John Abraham, "Climate Consensus - The 97%," The Guardian, January 28, 2014

A man cycles past furniture for sale at the roadside in Cameroon.
A man rides a bicycle in Cameroon; a country very vulnerable to climate change that it didn't cause, but developing innovative solutions to the problem. Photograph: Peter Treanor/Alamy
My research involves not only studying the Earth's climate, but also working to find clean energy solutions that will enable people and regions to have access to reliable electricity without increasing emissions of heat-trapping gases. In support of this effort, I recently traveled to Cameroon, which is on the western coast of Africa. There, in a town near the coast called Buea, I spent two weeks with my family and colleagues, working with a new university (Catholic University Institute of Buea, or CUIB for short) but more about that later.
First, readers of this column will note that I take a particular interest in the impacts of climate change that are being felt at regional or national levels. In particular, changes to weather patterns and how those changes are being driven by either natural or human causes is something I care deeply about. Fortunately, there is extensive literature available about observed changes or expected changes to climate and weather in and around Cameroon. For instance, some studies that focus on the impacts of climate change on the water cycle project that increases in rainfall and evaporation from lakes, rivers, oceans, and plants will have impacts that must be considered in future development planning.
Another study focused on the impacts that land-use changes and climate change have on Cameroon's forests; the study found future effects will be profound. Loss of forest lands will lead to loss of animal life in particular. More recent work confirms the vulnerability of Cameroon's forests to climate change. Those researchers found that while the people in Cameroon expressed a great deal of understanding and appreciation of climate change, the ability of the country to adapt to climate change was limited.

Perhaps the most detailed study regarding Cameroon's susceptibility to climate change was completed by the World Bank, which related agricultural output to climate change, in particular to changes in temperature and precipitation. The authors reported that since a large majority of the poor of Cameroon (and a significant percentage of the national GDP) work in agriculture, Cameroon as a nation is particularly sensitive to some of the changes we expect to see as the world warms.
And all of this brings us back to the university CUIB. I traveled there to find out what people on the ground observe. I spoke with the Dean of the School of Agriculture and Natural Resources, Dr. Laetitia Ako Kima. She told me,
"Farmers in this region are dependent on rain-fed agriculture and have observed erratic rainfall patterns and intensity which adversely affect agricultural activities and their livelihoods. Effects of this include among others, difficulty in following cropping calendars due to unpredictable and unseasonably long rainy periods, decline in crop yields, high disease incidence and crop losses, increased post-harvest losses and high labour costs, coupled with increasing incidents of HIV/AIDS.
These adversely affect their livelihoods, exacerbating already entrenched poverty which prevails at the grassroots level. There is therefore an urgent need for alternative coping strategies to mitigate prevailing circumstances."
 Outdoor community classrooms at CUIB.Outdoor community classrooms at CUIB.
So, how will a country like Cameroon plan for climate change and how do universities like CUIB contribute to those plans? First, we must recognize that climate change is a global problem. Emitted greenhouse gases do not abide by borders, nor do their impacts. In fact, as we've seen elsewhere, Cameroon is another country that has largely not caused the problem but may be impacted more significantly than other nations. The reason for this is threefold. First, since Cameroon's annual temperatures are confined to a small range, the biological systems are less capable of adapting to changes that modify the range. Second, Cameroon is heavily dependent on agriculture, which, in turn, depends on climate. Finally, Cameroon's limited financial resources make adaptation particularly difficult.
Countries that contribute least to climate change tend to be the most vulnerable to its impacts.Countries that contribute least to climate change tend to be the most vulnerable to its impacts, according to Samson et al. (2011).
Of course, Cameroon can, and will, play their role in reducing greenhouse gas emissions. However with a high unemployment rate and with challenges related to electrical power production and distribution, what can this country realistically achieve?
This was one of the questions I asked as I sat down with the Dean of the School Engineering, Dr. Asong Zisuh and his students. I quickly learned that innovative ideas from the young and entrepreneur-minded scientists and engineers might serve as a role model for us all. Dr. Asong Zisuh told me,
"The mission of CUIB (the entrepreneurial university) is to prepare servant leaders with moral and spiritual values to contribute to the sustainable development of their communities. Students are required to undertake entrepreneurial projects on issues related to sustainable development. Ongoing student projects in the the School of Engineering include: construction of wind turbines to generate clean and renewable electricity; construction of a solar drier to help conserve local farm products; drawing building plans for local housing that incorporate energy conservation practices; developing concepts for sustainable management of solid and liquid waste by local councils; biogas production for small scale use; and production of briquettes from bio-residues."
All of these very advanced and innovative ideas have been generated by enthusiastic undergraduate students. The young, it seems, express tremendous courage because they don't know what cannot be done. By this naïveté, they are sometimes able to accomplish what we old folks think is impossible.
The motivation for these environmental-conservation and climate change projects is not only related to the need to curb greenhouse gas emissions, but also to meet the growing demand for energy amidst huge supply shortages. Cameroon is a tropical country that receives a significant amount of daily sunshine and experiences a high generation rate of bio-residues, especially from agricultural activities. Thus, harnessing these available and inexpensive opportunities is required for the sustainable and economic development of the country.
Retrospectively, for someone like myself who works everyday on climate change, the slow progress can be demoralizing at times. I know that humans have the capacity to solve our climate and energy problems, we only lack the will. When I see what is happening at a small Cameroonian university that almost no one has heard of, I get encouraged. Maybe, just maybe, innovators like I've met at CUIB will be the change agents needed to preserve our future. Let's hope that's the case and let's support their efforts.

Monday, January 13, 2014

John Abraham: Global warming and energy – intertwined problems in Africa

Kenya is training for tomorrow's technology leaders to deal with today's climate and energy problems


by John Abraham, "Climate Consensus - The 97%," The Guardian, January 12, 2014

Kenya drought
A young girl in northern Kenya digs a hole in a river bed to retrieve water. Parts of Kenya are hit by drought as other areas get excessive rains. Photograph: Christopher Furlong/Getty Images
Much of my work involves the design and installation of clean and robustenergy sources in remote parts of the world. On a recent trip to Kenya, my family had the opportunity to tour the Lake Naivasha region in Kenya. This region contains a treasure of wildlife and was a filming location for the movie "Out of Africa." During a boat ride, we witnessed the impacts on climate change – not through academic journal articles or conference presentations – but through people who see climate change with their own eyes.
In past years, Lake Naivasha had seen dramatic reductions in water level. The coastline had changed and plants and animals had adapted to a new normal. Recently, however, extreme rains have raised the waters approximately 4 meters according to our guide. The new waterline had submerged and killed beautiful Acacia trees. After conversations with many other Kenyans, it was apparent that the reliable wet-dry weather patterns had become more erratic; you didn't have to witness dying Acacia trees when farmers throughout the country told similar tales. Extreme weather swings were evident here before our eyes.
Flooding in Western Kenya, submerged buildings and Acacia trees.Flooding in Western Kenya, submerged buildings and Acacia trees.
Kenyan culture (and much of Africa) is deeply rooted in the patterns of weather and climate; much of their economy depends on agricultural production. That dependency has given them much clearer foresight than others about how to plan for the changed future.
The entirety of Kenya has awakened to the threats of climate change, including the government, agricultural sectors, energy industries and the educational system. My journey to learn more about Kenya's plans brought me to the beautiful and large Kenyatta University campus, just northeast of Nairobi. There, very new and quickly growing programs in mechanical engineeringenergy and sustainability, and agricultural engineering are just a few of the programs training tomorrow's technology leaders to make an impact solving today's problems.
Among the many initiatives are goals to provide clean, renewable, and robust energy for the campus and the country. Some applications they are focusing on are wind-powered water-pumping systems. The plan is to design, manufacture, install, and service small-scale wind power systems that slowly pump water into elevated storage tanks throughout the day and night. Students, faculty, and staff draw the water is drawn down, typically during morning and evening hours. The prototype wind turbine will be adapted to manufacturing techniques used locally, near the university. It is hoped that wide-scale testing of the wind turbine system will occur over the next three years and thereafter, fast market penetration throughout Africa will be inevitable.
Another emerging technology coming from Kenyatta is the use of novel technologies for heating, ventilation, and air-conditioning (HVAC). By using thermochemical sorption technologies, sometimes with solar heating, Dr. Jeremiah Kiplagat (recent recipient of the African Education Leadership Outstanding Professor Award) and his colleagues are setting the framework for improving the performance of refrigeration systems using these methodologies.
As a third example, a series of faculty-led student projects have been completed to develop solar concentrating and tracking systems for heat generation and photovoltaic power generation. The research teams have developed effective and simple means of moving reflecting mirrors and parabolic concentrators with the sun throughout the day to increase the amount of absorbed solar energy and increase the efficiency of the overall system.
While the faculty and staff are at the forefront in technology development projects such as these, much credit must be given to the administration. With implementation of new degrees such as doctoral programs in sustainability and masters programs in mechanical engineering, electrical engineering, engineering hydrology, and biomedical engineering, with a focus on solving the energy and health problems that are prevalent in the East African region, this university, and the country as a whole are destined to remain leaders in their geographical region.
It is clear from formal academic studies and from anecdotal evidence that developing countries that rely upon agriculture will suffer greatly from climate change in the coming decades. It is hence apparent that the solutions to climate change, such as accelerated implementation of clean and renewable power, must be implemented with great wisdom so that people in these regions are able to access the same low-cost electricity that other nations have enjoyed. In this regard, the climate-energy problem is often thought of as a double-edged sword – solutions to the climate problem make access to low-cost electricity more difficult.
Currently, the major source of energy in Kenya is hydropower. This is why the School of Engineering at Kenyatta University has also partnered with regional and international organizations to promote climate mitigation in water and energy sectors. An example is the research being carried out by Dr. Luke Olang in collaboration with IGAD climate center on developing a drought-monitoring tool for the greater horn of Africa in general. The same research team is also actively involved in water management strategies in the vulnerable Mara River Basin, considered a World Heritage site due to the Great Annual Wildebeest Migration.
What Kenyatta University is showing the world is that it is possible to solve both the energy and the climate problems together. Novel energy solutions using locally available technology and manufacturing techniques can build economies, provide low-cost energy, and preserve the future climate for our children. This type of systematic planning and dedication gives me hope that our future climate and energy problems can be solved.
Perhaps the vision is best expressed by Prof. Chris Shisanya, Dean School of Humanities and Social Sciences who told me,
"We at Kenyatta University have decided to prepare our students early enough during their study programmes to confront the challenges posed by climate change. We are now offering such courses as MSc. (Integrated Watershed Management) and MSc. (Climate Change and Sustainable Development), whose main focus is on adaptation to climate change. We believe that by exposing our students to such knowledge, they will be better equipped to help communities in Kenya's rural landscapes enhance their resilience to climate change impacts."
http://www.theguardian.com/environment/climate-consensus-97-per-cent/2014/jan/12/global-warming-energy-intertwined-africa

Saturday, April 13, 2013

"Unsustainable fuelwood extraction from South African savannas," by K. J. Wessels et al., ERL 8 (2013); doi: 10.1088/1748-9326/8/1/014007

Environmental Research Letters, 8 (2013) 014007; doi: 10.1088/1748-9326/8/1/014007


UNSUSTAINABLE FUELWOOD EXTRACTION FROM SOUTH AFRICAN SAVANNAS

K. J. Wessels1,2, M. S. Colgan3, B. F. N. Erasmus4, G. P. Asner3, W. C. Twine4, R. Mathieu5, J. A. N. van Aardt6, J. T. Fisher4 and I. P. J. Smit7

Abstract

Wood and charcoal supply the majority of sub-Saharan Africa's rural energy needs. The long-term supply of fuelwood is in jeopardy given high consumption rates. Using airborne light detection and ranging (LiDAR), we mapped and investigated savanna above-ground biomass across contrasting land uses, ranging from densely populated communal areas to highly protected areas in the Lowveld savannas of South Africa. We combined the LiDAR observations with socio-economic data, biomass production rates and fuelwood consumption rates in a supply–demand model to predict future fuelwood availability. LiDAR-based biomass maps revealed disturbance gradients around settlements up to 1.5 km, corresponding to the maximum distance walked to collect fuelwood. At current levels of fuelwood consumption (67% of households use fuelwood exclusively, with a 2% annual reduction), we calculate that biomass in the study area will be exhausted within thirteen years. We also show that it will require a 15% annual reduction in consumption for eight years to a level of 20% of households using fuelwood before the reduction in biomass appears to stabilize to sustainable levels. The severity of dwindling fuelwood reserves in African savannas underscores the importance of providing affordable energy for rural economic development.

Received 4 October 2012, accepted for publication 12 December 2012 
Published 17 January 2013


Open access article:  http://iopscience.iop.org/1748-9326/8/1/014007/article

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