The desertification-climate change nexus will be a key topic of discussion at the global scientific conference, the first such event to be held in support of the United Nations Convention to Combat Desertification (UNCCD). Organized by the Dryland Science for Development (DSD) Consortium, the event (titled "Understanding Desertification and Land Degradation Trends") is being held in connection with the Ninth Session of the Conference of the Parties (COP9) to the UNCCD.
The Conference highlights the importance of developing and implementing science-based methods for monitoring and assessing land degradation and underlines the need for a holistic approach to understanding and overcoming the devastating impact of desertification.
Drylands comprise more than 40 percent of global land area and are home to nearly 35 percent of its people, according to a white paper prepared for the UNCCD conference. As much as 20 percent of this land has already been affected by desertification, defined as land degradation (that is, loss of the land's productive capacity), caused by a combination of human activity and climate conditions.
"We need to view drylands as the front lines in our global effort to help the rural poor cope with climate change," said William Dar, Director General of the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), a DSD member supported by the Consultative Group on International Agricultural Research (CGIAR). Dar also chairs UNCCD's Committee on Science and Technology (CST), under whose auspices the conference is being organized by the DSD Consortium.
"The fragile ecosystems of the dry areas are highly vulnerable to land degradation and desertification. Farmers in these areas already face harsh and variable weather and limited resources," added Mahmoud Solh, Director General of the CGIAR-supported International Center for Agricultural Research in the Dry Areas (ICARDA) and Chair of the DSD Consortium. "We must clearly demonstrate progress in helping them deal with those limitations of today, if they are to have any hope of adapting to climate change tomorrow."
Among the immediate impacts of desertification are dramatic losses of biodiversity (an assessment carried out in Rajasthan, India, observed a drop from 54 to 9 plant species) and drastic declines in agricultural productivity. In these and other ways, drylands can quickly lose their capacity to provide adequate livelihoods for people, thus deepening rural poverty and worsening social and political instability.
Degraded drylands also cease to perform key environmental services, such as carbon sequestration. Soils in dry areas are estimated to contain more than a quarter of the world's total stores of organic carbon. Yet, as these lands are degraded, they release carbon into the atmosphere, accounting for about 4 percent of total global emissions each year.
Climate change is expected to expand drylands by 11 percent globally, according to the fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC). And scientists predict this will worsen desertification around the world, mainly by increasing the frequency and severity of drought.
So far, the main technical barrier to progress in combating desertification, explains the white paper, has been a lack of standardised, science-based methods for monitoring and assessing land degradation and progress in combating it through advances in science and technology. Current procedures have tended to focus more on symptoms than on underlying causes and potential solutions. And they have failed to deliver results in forms that help policy makers decide how best to confront the problem on a national and regional scale.
"Just as the IPCC marshaled massive scientific evidence to dispel doubts about both the causes and consequences of climate change, the UNCCD must now build a stronger technical basis for cost-effective actions to ward off desertification," said ICRISAT scientist Mark Winslow. "The Conference will help do that by bringing together state-of-the art approaches, such as advanced modelling, mapping, high-resolution remote sensing and community participation. To be effective, these approaches must then be connected with government decision-making."
A wide variety of such approaches are being developed and tested under the Land Degradation Assessment in Drylands (LADA) Project, which is being carried out in Argentina and five other developing countries by the Food and Agriculture Organization (FAO) of the United Nations and the United Nations Environment Programme (UNEP).
While seeking better ways to monitor and assess land degradation, scientists also point to multiple avenues for enabling rural people to reverse the process through sustainable land management.
In the dry Sudano-Sahelian region of West Africa, for example, ICRISAT researchers have devised an approach called "bioreclamation of degraded lands." With this approach, associations of about 100 landless women gain access to degraded farmland from village chiefs and then restore it to productivity through a combination of rainwater harvesting practises (such as the use of microcatchments), application of compost or manure to improve soil fertility and planting of drought-tolerant indigenous fruits trees and vegetables.
One especially suitable tree species is the Apple of the Sahel, or Pomme du Sahel in French (Ziziphus mauritania), whose apple-shaped fruit possesses ten times more vitamin C than apples and is also rich in iron, calcium, phosphorous and essential amino acids. Another is the Moringa tree (Moringa stenopetala), whose leaves have seven times more vitamin C than oranges, four times more vitamin A than carrots, four times more calcium than milk (plus double the protein) and three times more potassium than bananas.
Set for widespread adoption, the approach shows "great promise for raising women's incomes, improving family nutrition and reversing land degradation," said Dar.
A similar combination of water-harvesting and groundwater-recharging structures, together with planting of hardy trees, has proved effective for recuperating degraded community land in several watersheds of eastern Rajasthan State, India. Increased availability of surface and groundwater has enabled farmers to increase the productivity, profitability and diversity of crop production, leading to a 28 percent increase in per capita income.
ICARDA is helping to rehabilitate and revegetate thousands of hectares of heavily degraded rangelands in dry areas and to help halt or even reverse desertification using community based approaches in integrated research sites throughout North Africa and Central and West Asia.
ICARDA scientists are working closely with rural communities to combine integrated water management, water harvesting, conservation agriculture and better farming practises to improve the productive capacity of the limited resources in dry areas. ICARDA has pioneered the implementation of a laser guidance system to help build rainwater micro-catchments, which support fodders shrubs and stop erosion in marginal lands. This work has the potential to provide benefits to millions of farmers and pastoralists in dry areas.
Many other such approaches are being supported and documented by the World Overview of Conservation Approaches and Technologies (WOCAT), a network of specialists, who are key partners in assessing land degradation.
"Science and technology hold the key to coping with the desertification-climate change nexus," said Dar. "With the right combination of holistic policies and sustained global action, path-breaking science can help curb desertification and land degradation, improving the livelihoods of millions of poor people in drylands."
