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 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.

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, 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.

http://www.theguardian.com/environment/climate-consensus-97-per-cent/2014/jan/28/cameroon-vulnerable-tackles-climate-change

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

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.

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 engineering, energy 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

"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. Wessels^1,2, 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

New Map Sharpens View of African Ecosystems

Posted: 11 Apr 2013 09:49 AM PDT A team of African and North American scientists led by the U.S. Geological Survey and NatureServe, a conservation non-profit organization, has created a series of continent-wide ecosystem maps that offer the most detailed portrayals of Africa's natural setting yet produced. The new maps and related data on landforms, geology, bioclimates, and vegetation can be used across Africa for conservation planning and resource management, as well as for impact assessments of climate change and changes in land use, such as agriculture, deforestation, and urbanization.  "This was a multi-organizational, international collaboration to create new earth science datasets for the entire continent at finer resolutions than ever before," said Matt Larsen, USGS Associate Director for Climate and Land Use Change. "An added benefit is that this information about ecosystem conditions can be put to many different uses. It will have tremendous utility beyond ecosystem assessments."  USGS and NatureServe researchers collaborated with the Regional Centre for Mapping of Resources for Development (RCMRD), based in Nairobi, Kenya. RCMRD hosted two workshops where invited experts from many African nations developed a new classification of African ecosystems and provided location data for the newly classified ecosystems. Overall, a total of 37 experts from 18 countries worked together to formulate the ecosystem classifications (126 distinct ecosystems were mapped) and produce the maps at a base resolution of 90 meters.  "This much improved baseline of Africa's ecosystem conditions has the potential for more accurate carbon assessment studies in Africa," observed USGS scientist Roger Sayre, lead author of the publication.  Determination of biological carbon stocks in ecosystems is an emerging science. Currently, carbon stocks are assessed in general biome categories like forests, grasses, shrublands, wetlands, deserts, and agricultural lands. The increased classification resolution supplied by the new African ecosystems maps will facilitate a more robust assignment of carbon inventories to a greater, more precise number of biological sources.  The Association of American Geographers (AAG) provided key support for the final publication. The publication is available in digital form from the USGS.    A new map of standardized terrestrial ecosystems of Africa. 2013. Sayre, Roger; Comer, Patrick; Hak, Jon; Josse, Carmen; Bow, Jacquie; et al., African Geographical Review. Learn more: USGS Global Ecosystems

Mapping the future of climate change in Africa

Mapping the future of climate change in Africa

August 2, 2012

Please see the link at the end of the article in order to see the figures.

The composite picture highlights areas of chronic insecurity where the four sources of vulnerability coalesce. Credit: Joshua Busby et al. 

Our planet's changing climate is devastating communities in Africa through droughts, floods and myriad other disasters.

Using detailed regional climate models and geographic information systems, researchers with the Climate Change and African Political Stability (CCAPS) program developed an online mapping tool that analyzes how climate and other forces interact to threaten the security of African communities. The program was piloted by the Robert S. Strauss Center for International Security and Law at The University of Texas at Austin in 2009 after receiving a $7.6 million five-year grant from the Minerva Initiative with the Department of Defense, according to Francis J. Gavin, professor of international affairs and director of the Strauss Center. 

"The first goal was to look at whether we could more effectively identify what were the causes and locations of vulnerability in Africa, not just climate, but other kinds of vulnerability," Gavin said. CCAPS comprises nine research teams focusing on various aspects of climate change, their relationship to different types of conflict, the government structures that exist to mitigate them, and the effectiveness of international aid in intervening. Although most CCAPS researchers are based at The University of Texas at Austin, the Strauss Center also works closely with Trinity College Dublin, the College of William and Mary, and the University of North Texas. 

"In the beginning these all began as related, but not intimately connected, topics" Gavin said, "and one of the really impressive things about the project is how all these different streams have come together." Africa is particularly vulnerable to the effects of climate change due to its reliance on rain-fed agriculture and the inability of many of its governments to help communities in times of need. The region is of increasing importance for U.S. national security, according to Gavin, because of the growth of its population, economic strength and resource importance, and also due to concerns about non-state actors, weakening governments and humanitarian disasters.

Although these issues are too complex to yield a direct causal link between climate change and security concerns, he said, understanding the levels of vulnerability that exist is crucial in comprehending the full effect of this changing paradigm. 

The vulnerability mapping program within CCAPS is led by Joshua Busby, assistant professor at the Lyndon B. Johnson School of Public Affairs. 

To determine the vulnerability of a given location based on changing climate conditions, Busby and his team looked at four different sources: (1) the degree of physical exposure to climate hazards, (2) population size, (3) household or community resilience, and (4) the quality of governance or presence of political violence. 

Climate security vulnerability in Somalia is greatest in and around the capital of Mogadishu and the far north. Insecurity in these areas is driven by all four dimensions of vulnerability but particularly by low resilience and poor governance. Credit: Joshua Busby et al. 

The first source records the different types of climate hazards which could occur in the area, including droughts, floods, wildfires, storms and coastal inundation. However, their presence alone is not enough to qualify a region as vulnerable. 

The second source—population size—determines the number of people who will be impacted by these climate hazards. More people create more demand for resources, potentially making the entire population more vulnerable. 

The third source looks at how resilient a community is to adverse effects, analyzing the quality of their education and health, as well as whether they have easy access to food, water and health care. 

"If exposure is really bad, it may exceed the capacity of local communities to protect themselves," Busby said, "and then it comes down to whether or not the governments are going to be willing or able to help them." 

The final source accounts for the effectiveness of a given government, the amount of accountability present, how integrated it is with the international community, how politically stable it is, and whether there is any political violence present. 

Busby and his team combined the four sources of vulnerability and gave them each equal weight, adding them together to form a composite map. Their scores were then divided into a ranking of five equal parts, or quintiles, going from the 20 percent of regions with the lowest vulnerability to the 20% with the highest. The researchers gathered information for the tool from a variety of sources, including historic models of physical exposure from the United Nations Environment Programme (UNEP), population estimates from LandScan, as well as household surveys and governance assessments from the World Bank's World Development and Worldwide Governance Indicators. This data reflects past and present vulnerability, but to understand which places in Africa would be most vulnerable to future climate change, Busby and his team relied on the regional climate model simulations designed by Edward Vizy and Kerry Cook, both members of the CCAPS team from the Jackson School of Geosciences. 

Enlarge Children in the foothills of Drakensberg mountains in South Africa who still live in traditional rondavels on family homesteads. Credit: Credit: Todd G. Smith, CCAPS Program. 

Vizy and Cook ran three, 20-year nested simulations of the African continent's climate at the regional scales of 90 and 30 kilometers, using a derivation of the Weather Research and Forecasting Model of the National Center for Atmospheric Research. One was a control simulation representative of the years 1989-2008, and the others represented the climate as it may exist in 2041-2060 and 2081-2100. 

"We're adjusting the control simulation's CO2 concentration, model boundary conditions, and sea surface temperatures to increased greenhouse gas forcing scenario conditions derived from atmosphere-ocean global climate models. We re-run the simulation to understand how the climate will operate under a different, warmer state at spatial resolutions needed for regional impact analyses," Vizy said. 

Each simulation took two months to complete on the Ranger supercomputer at the Texas Advanced Computing Center (TACC). "We couldn't run these simulations without the high-performance computing resources at TACC, it would just take too long. If it takes two months running with 200 processors, I can't fathom doing it with one processor," Vizy said. 

Researchers input data from these vulnerability maps into an online mapping tool developed by the CCAPS program to integrate its various lines of climate, conflict and aid research. CCAPS's current mapping tool is based on a prototype developed by the team to assess conflict patterns in Africa with the help of researchers at the TACC/ACES Visualization Laboratory (Vislab), according to Ashley Moran, program manager of CCAPS. 

"The mapping tool is a key part of our effort to produce new research that could support policy making and the work of practitioners and governments in Africa," Moran said. "We want to communicate this research in ways that are of maximum use to policymakers and researchers." 

The initial prototype of the mapping tool used the ArcGIS platform to project data onto maps. Working with its partner Development Gateway, CCAPS expanded the system to incorporate conflict, vulnerability, governance and aid research data. After completing the first version of their model, Busby and his team carried out the process of ground truthing their maps by visiting local officials and experts in several African countries, such as Kenya and South Africa. 

"The experience of talking with local experts was tremendously gratifying," Busby said. "They gave us confidence that the things we're doing in a computer lab setting in Austin do pick up on some of the ground-level expert opinions." 

Busby and his team complemented their maps with local perspectives on the kind of impact climate was already having, leading to new insights that could help perfect the model. For example, local experts felt the model did not address areas with chronic water scarcity, an issue the researchers then corrected upon returning home. According to Busby, the vulnerability maps serve as focal points which can give way to further analysis about the issues they illustrate. 

Some of the countries most vulnerable to climate change include Somalia, Sierra Leone, Guinea, Sudan and parts of the Democratic Republic of Congo. Knowing this allows local policymakers to develop security strategies for the future, including early warning systems against floods, investments in drought-resistant agriculture, and alternative livelihoods that might facilitate resource sharing and help prevent future conflicts. 

The next iteration of the online mapping tool to be released later this year will also incorporate the future projections of climate exposure from the models developed by Vizy and Cook. The CCAPS team publishes their research in journals like Climate Dynamics and The International Studies Review, carries out regular consultations with the U.S. government and governments in Africa, and participates in conferences sponsored by concerned organizations, such as the United Nations and the United States Africa Command. 

"What this project has showed us is that many of the real challenges of the 21st century aren't always in traditional state-to-state interactions, but are transnational in nature and require new ways of dealing with," Gavin said. 

Provided by University of Texas at Austin

http://phys.org/news/2012-08-future-climate-africa.html 

Said AlSarmi & Richard Washington, J. Geophys. Res., 116 (2011), Recent observed climate change over the Arabian Peninsula

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 116, D11109, 15 PP., 2011
doi:10.1029/2010JD015459

Recent observed climate change over the Arabian Peninsula

Key Points

• Arabian Peninsula is warming significantly
• Many Arabian Peninsula stations reported high warming rates
• The warming in minimum temperature is the highest and most spatially coherent

Said AlSarmi and Richard Washington

Climatology Research Group, Oxford University Centre for the Environment, University of Oxford, Oxford, UK

Abstract

We have examined trends in temperature and precipitation parameters for the Arabian Peninsula (AP) during the last 2 to 3 decades. The data set has been carefully quality controlled and checked for homogeneity. Although of low density (21 stations) and relatively short time period, a clear picture of climate change in the region has emerged. The general pattern of the AP mean annual temperature trend is one of warming, with 14 of 21 stations show statistically significant warming at 0.05 level and most at 0.001 level and only one (Seeb) showing statistically significant cooling. The highest statistically significant mean annual warming trends are found in Oman (Sur = 1.03 °C decade⁻¹) and Emirates (Dubai = 0.81 °C decade⁻¹). The season of maximum warming in mean temperature is March to April. The highest monthly mean temperature trend in the AP occurs in Sur in May (1.47 °C decade⁻¹). There is a broad statistically significant increase in mean annual maximum temperature in AP in 12 out of 21 stations, with the highest trends in central and eastern/southeastern AP. Only SW AP and the Gulf of Oman do not show warming. The highest monthly maximum temperature trend in the AP occurs in Bahrain in March (2.27 °C decade⁻¹). The second highest significant warming trends are reported in Doha in February (1.54 °C decade⁻¹). For minimum temperature, 16 out of 21 stations show statistically significant warming trends, with the highest annual trends observed in the Emirates (Dubai = 1.24 °C decade⁻¹), northwest Oman (Sohar = 1.17 °C decade⁻¹) and Qatar (Doha = 1.13 °C decade⁻¹). The highest monthly minimum temperature warming rate occurred in October. Both Dubai and Kuwait reported the highest significant rate of 2.00 °C decade⁻¹. The general mean annual diurnal temperature range trend is negative in the AP, with six out of 21 stations show statistically significant negative trends while three stations show statistically significant positive trends. Trends in mean annual precipitation are significant at only two stations which show a decrease in precipitation.

http://www.agu.org/pubs/crossref/2011/2010JD015459.shtml

Elinor Breman, Lindsey Gillson & Kathy Willis, The Holocene, How fire and climate shaped grass-dominated vegetation and forest mosaics in northern South Africa during past millennia

The Holocene, published online before print April 21, 2011; doi: 10.1177/0959683611400196

How fire and climate shaped grass-dominated vegetation and forest mosaics in northern South Africa during past millennia

1. Elinor Breman
   1. Oxford University, UK

1. Lindsey Gillson
   1. University of Cape Town, South Africa

1. Kathy Willis
   1. University of Oxford, UK

Abstract

Grassland and savanna are globally important ecosystems, both ecologically and economically. These grass-dominated systems are at risk from current and future climate change and increasing anthropogenic impact. Key questions for understanding the resilience and variability of grass-dominated ecosystems under current and future environmental conditions include: How have these systems responded to climate change and disturbance in the past? What are the principal driving agents responsible for their present-day composition and distribution? Do the palaeoecological data provide evidence for feedbacks between climate, fire and anthropogenic activities? In this study, the temporal dynamics of grassland, savanna and forest in the summer rainfall region of northern South Africa were reconstructed for the last ∼6500 years. Palaeoecological techniques used include analyses of fossil pollen, charcoal and stable isotopes. Data from two sites located at the present-day grassland-savanna ecotone in Mpumalanga province of South Africa are reported. Results indicate that a mosaic of grassland, savanna and Podocarpus forest occupied the landscape throughout the late Holocene, with grassland and forest dominating higher altitudes, and savanna and forest lower altitudes. Podocarpus forest retreated and grass-dominated vegetation expanded its range around 1800 cal. yr BP at the lower altitude site (Lowveld) and 600 cal. yr BP at the higher altitude site (Highveld), representing a change from a stable state forest savanna/grassland mosaic to an increasingly grass-dominated system. Climatic stress, changes in fire regime and anthropogenic impact led to the vegetation transitions recorded, and resulted in changes in water and nutrient cycles. In an increasingly warm world, with fluctuating water availability and heightened anthropogenic use of natural resources, the future of grass-dominated ecosystems appears far from stable. 

http://hol.sagepub.com/content/early/2011/04/21/0959683611400196.abstract