Africa’s climate already poses grave risks to the continent’s people and economies, and global warming promises to intensify the problem. A factual risk-management solution can help.
Even before global warming became an issue, many African countries were unusually vulnerable to floods, droughts, and heat waves. Indeed, if there were to be no further change in Africa’s climate, its current state already presents grave risks to the continent’s people and economies. Global warming could trigger more frequent and severe weather disasters, shifts in rainfall patterns and climate zones, and rising sea levels.
For African nations, adapting to these possibilities is an urgent necessity. To do so, their leaders must answer some difficult questions. What climate-related losses could these economies sustain over the coming decades? How much can be averted and through what measures? Which investments will be required to finance them? Will the benefits outweigh the costs? We believe that such questions can be answered systematically through a factual risk-management approach that African leaders can use to assess climate’s impact on their countries and to find ways of minimizing it at the lowest cost to society.
Knowledge about future climate trends—particularly their local impact—is incomplete, so policy and investment choices must be made under uncertainty. Yet enough is known to build plausible climate change scenarios as a basis for these decisions, even in developing countries. Such scenarios can help decision makers to identify adaptation measures useful against a range of climate change outcomes. Cost-effective responses can address much of the identified risk: depending on the country studied,1 40 to 70 percent of the losses expected by 2030 could be averted—even under severe climate change scenarios—through adaptation measures whose economic benefits outweigh their costs. In almost all cases, however, at least some risk cannot be averted through known measures.
Many adaptation measures would strengthen economic growth in developing countries; in Mali, for instance, climate-resilient agricultural development could generate millions of dollars annually in additional revenues. Measures with demonstrated net economic benefits could also attract investments and trigger valuable new innovations and partnerships. Indeed, well-targeted, early investments to improve climate resilience—through infrastructure development, technological advances, capacity improvements, new systems and behavior, and risk transfer measures—will probably be cheaper and more effective for the world community than complex disaster relief efforts after the event.
A fact-based approach can provide valuable input into the overall decision-making process. Among other things, it recognizes the importance of cost–benefit considerations, makes it possible to put “price tags” on current and future climate risks, and lets decision makers develop plans to help businesses adapt to them.
In northwestern Africa, stretching deep into the Sahara, Mali is a mostly dry nation, subject to frequent droughts. Increasing temperatures and decreasing rainfall tell of a shift in climate zones as the desert moves south over productive land. In these regions, farmers dependent on agriculture and livestock already face trying periods of drought and have few options to overcome them. Many are moving to the cities, others to the countries less arid south. Our study focused on Mopti, an important agricultural area in the central region.
Mali has a wide variety of natural environments, ranging from a Saharan climate in the north to the more tropical south. From year to year, its rainfall levels are among the world’s most variable. Annual floods during the rainy season in the Niger River’s interior delta benefit agriculture but may harm local populations (Exhibit 1). Mali also faces additional hazards from climate change: drought is expected to increase in frequency and severity, weakening the country’s agriculture and GDP. The climate zone shift—the combined effect of rising average temperatures and declining average rainfall—has already pushed the country’s agroecological zones to the south over the past 50 years, with average rainfall down by about 200 millimeters and average temperatures up by 0.5°C over the same period.
Desertification and climate zone shift have multiple causes, with complex interactions. The impact from climate change is aggravated by farming and domestic practices, such as slash-and-burn agriculture (which erodes the soil) and deforestation, mostly to meet 90 percent of Mali’s cooking and heating requirements. (Forest cover has decreased by almost 50 percent since the 1980s.) Nonetheless, local adaptations could eliminate a significant share of the loss due to climate change, and it is important to recognize that farmers have already developed the kinds of techniques that will help them cope. Diversity in crop cycles—already widely practiced by Malian farmers—will be essential. Genetic variation in plants helps to make agriculture in areas with higher climate risks more resilient to them. Also advantageous will be the farmers’ tendency to spread out geographically for access to different types of soils and water sources.
In 2006, the value of Mali’s crops and livestock was estimated at $840 million and $620 million, respectively. Projections to 2030 take into account the most valuable agricultural crops (cotton, maize, millet, rice, and sorghum) and livestock (for eggs, meat, and milk). Following historical expectations, the five main crops’ value would increase by 46 percent, to $1,220 million (1.6 percent annual growth). In a more optimistic scenario, that level would more than double, to $2,470 million (4.6 percent annual growth).
The significant uncertainty about climate change has spawned a range of climate projections for rainfall, while temperatures are consistently projected to increase significantly. Local climate models allowed us to consider three scenarios for a climate zone shift by 2030. Under the moderate-change one, temperatures would rise by 1.2°C and annual rainfall would decrease by 2.2 percent. The high-change positive scenario projects an increase in rainfall and temperatures of 8.1 percent and 0.9°C, respectively, while the high-change negative scenario anticipates a decrease in rainfall of 10.6 percent and an increase in temperatures of 1.4°C. Under all three, Mali would suffer economic losses by 2030. The pessimistic high-change scenario could involve losses of about $300 million annually (some 15 percent of the value of agriculture and livestock); the optimistic scenario, losses of $120 million annually (6 percent).
These losses will probably be offset, to some extent, even in the absence of specific adaptation measures. Agricultural production in Mali is likely to increase in value through the encouragement of farming in the regions best suited to it and the promotion of the right mix of crops. The human migrations required should happen naturally. Still, such measures would not cover the full expected climate-related economic decline.
Measures to increase productivity by encouraging the development of assets primarily in the most promising areas could compensate for losses elsewhere. Simulations show that by 2030, a migration of one million people could raise agricultural production by 6 percent more than population growth spread evenly across regions would. The migration of 1.5 million people by 2030 could raise production by an additional 8 percent—an overall 14 percent increase compared with the base case. But such controversial measures might promote conflict and increase competition for resources. Infrastructure and asset-based measures could make semi-arid areas substantially more resilient; however, so accelerated migration isn’t essential.
Source: Science Daily