Category Archives: Ecological Management

Ecological Management, General, Networks

Ethan Zuckerman reviews Infotopia and discusess social decision-making

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On My heart’s in Accra Ethan Zuckerman reviews Cass Sunstein’s book “Infotopia”, which discusses how the internet changes group decision making processes. Zuckerman writes:

Infotopia… In his new book, Infotopia, [Sunstein’s] become a cyber-enthusiast to an extent that would have been hard to imagine a few years ago. Specifically, he’s excited about the ways new online tools make it possible for groups of people to assemble information and accumulate knowledge. He’s become a devotee of Friedrich Hayek, the Austrian economist who saw markets, first and foremost, as a way to aggregate information held by a large group of people. There’s ample evidence that Hayek was right in an examination of the failure of planned economies – smart men sitting in a room do a far worse job of setting the price of copper ore or bread than the collected actions of thousands of consumers, iterated over time.

Markets aren’t the only way to aggregate information from a large group of people. Deliberative groups, where a set of people get together and share the knowledge they have on a problem or an issue, are favored by many political theorists, including Jürgen Habermas, who bases much of his political philosophy on the establishment of a public sphere where deliberation can occur. Sunstein is deeply suspicious of the optimistic claims made for deliberation, and cites a wealth of studies that demonstrate that deliberation, in many cases, leads to bad decisions and the reinforcement of extreme views.

(You can think of Infotopia as a caged deathmatch between Hayek and Habermas, streamed live on the Internet. Habermas taps out somewhere around page 200.)

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Ecological Management, Ideas

Elinor Ostrom answers 12 questions

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Elinor Ostrom is asked 12 questions in the German journal GAIA (4|2006). Arun Agrawal introdues Elinor “Lin” Ostrom in the journal as follows:

Few social scientists can lay claim to the kind of achievements for which Lin is famous: inventing and consolidating the commons as a whole new field of investigation, launching new institutions that shape the research careers of hundreds of social scientists, and influencing public policy in an entirely new direction in relation to natural resource governance. …The work that has brought her the acclaim and admiration of peers and the adulation of younger scholars has effectively countered widely accepted orthodoxies about the ineffectiveness of common property. Lin’s scholarly contributions are founded upon the bedrock of evidence from literally tens of thousands of studies, refutable propositions based in fundamental social science, and rock-solid, theoretically informed, rigorous empirical and experimental research. It would be no exaggeration to say that there is scarcely a political scientist better known within and outside the discipline.

A few of GAIA’s questions and Elinor Ostrom’s answers are below. Its great to discover that she thinks the work of the Resilience Alliance is exciting.

7. What field of research in environmental sciences – besides the one you are working in – do you consider most exciting?

The Resilience Alliance is, in my opinion, producing some of the most exciting contemporary research by bringing together centers throughout the world to study the resilience of ecological systems to natural- and human-induced disturbances.

8. Can you name any person or event that has had a particular influence on your commitment to environ- mental issues?

Before reading the work of Robert Netting in the early 1980s, I had no inkling it would ever be efficient to allocate land for human use using common property. I understood that water and fish existed in common-pool resources and required a variety of property-rights systems, but I thought land was a private good and needed private ownership to be allocated efficiently. Netting’s analysis was unnerving. He asked why Alpine farmers used private ownership to manage their valley farmlands, but the same farmers used forms of common property to manage Alpine meadows. His analysis demonstrated that forms of common property were more effective than private ownership when land had low productivity, when rainfall and other nutrients were spatially and temporally patchy, and when substantial economies of scale in building infrastructure existed. His in-depth evidence was substantial and the theoretical argument broadened my horizon tremendously. It blew my mind!

10. What knowledge about the environment would you like to pass on to young people?

Young people need to learn about the diversity of ecosystems and the diversity of institutional arrangements that humans have crafted to cope effectively with different settings and problems.

Humans have used a large set of rules in various combinations in the effort to match the specific characteristics of particular resource systems. Rules related to who can access, harvest from, manage, exclude others, and sell aspects of a resource system are the building blocks of resource use and protection situations. When systems fail, we need to use empirically warrantable diagnostic theories to analyze the sources of failure and which rules need to be changed (and how) to create a more sustainable future.

11. What are you reading at the moment?

I am enjoying reading Frans de Waal’s Primates and Philosophers: How Morality Evolved. Since I have studied reciprocity and fairness among humans in the experimental lab and in field settings, it is fascinating to read his discussion of these processes among chimpanzees and capuchin monkeys.

12. Which question – apart from the ones we raised – is the most important one?

What can each one of us do every day to improve our environment? If we think that the only answers to environmental problems are what “the” government undertakes, we face a real tragedy.

Ecological Management, General, Greenlash

Gilbert White: Floods are acts of God, but flood losses are largely acts of man

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Gilbert White a pioneer in understanding the social-ecological nature of natural disasters died recently in Colorado. He died, in early October 2006, age 94 after a long and diverse career that centered on the impact of flooding.

White argued that ‘hard’ engineering solutions to flooding, such as dams and levees, frequently produced pathological results. His PhD research at the University of Chicago “Human adjustment to floods,” showed river engineering had increased, rather than decreased, the costs of floods, because river engineering resulted in more settlement in the floodplain, increasing vulnerability to large flood.

The Natural Hazards Center at the University of Colorado at Boulder maintains a Gilbert White archive.

The University of Colorado has an obituary. The Washington Post also has an obituary that quotes Gilbert White:

While watching the German occupation of France, I became convinced that man can no more conquer or preserve a civilization by war than he can conquer nature solely by engineering force,” Dr. White told broadcaster Edward R. Murrow for the radio program “This I Believe” in 1951.

“I found that an occupying army or a concentration camp can repress men’s basic beliefs but cannot change them. The good life, like the balance of all the complex elements of a river valley, is founded upon friendly adjustment. . . . It embraces confidence in fellowship, tolerance in outlook, humility in service and a constant search for the truth.”

Ecological Management, Millennium Ecosystem Assessment

Millennium Ecosystem Assessment: Research Needs

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In an enhanced Policy Forum in Science 314 (5797): 257, Steve Carpenter and several other senior participants from the Millennium Ecosystem Assessment (MA) that outlines the Research Needs identified by the MA. They highlight the need for:

  • Theory Linking Ecological Diversity & Dyanmics
  • Briding Scales; Monitoring
  • Research that Assesses Policy Success;
  • Improved understanding of Social-Ecological Change
  • Improved methods of Ecological Valuation.

Their comments on Ecological theory, learning from policies, and Social-Ecological theory are of particular interest to resilience research. They write:

We lack a robust theoretical basis for linking ecological diversity to ecosystem dynamics and, in turn, to ecosystem services underlying human well-being. We all need this information to understand the limits and consequences of biodiversity loss and the actions needed to maintain or restore ecosystem functions.

The most catastrophic changes in ecosystem services identified in the MA involved nonlinear or abrupt shifts. We lack the ability to predict thresholds for such changes, whether or not a change may be reversible, and how individuals and societies will respond. Thus, the risks of ecosystem catastrophes are poorly quantified. Major ecosystem degradation tends to occur as syndromes of simultaneous failure in multiple services. For example, the populous dry lands of the world are facing a combination of failing crops and grazing, declining quality and quantity of fresh water, and loss of tree cover. Similarly, many rivers and lakes have experienced increases in nutrient pollution (eutrophication), toxicity, and biodiversity loss.

Relations between ecosystem services and human well-being are poorly understood. One gap relates to the consequences of changes in ecosystem services for poverty reduction. The poor are most dependent on ecosystem services and vulnerable to their degradation. Empirical studies are needed.

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Ecological Management, Greenlash, Ideas, Vulnerability

The Vegetable-Industrial Complex

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Michael Pollan article The Vegetable-Industrial Complex in the October 15th New York Times describes an example of Holling’s pathology of natural resource management in agriculture.

Wendell Berry once wrote that when we took animals off farms and put them onto feedlots, we had, in effect, taken an old solution — the one where crops feed animals and animals’ waste feeds crops — and neatly divided it into two new problems: a fertility problem on the farm, and a pollution problem on the feedlot. Rather than return to that elegant solution, however, industrial agriculture came up with a technological fix for the first problem — chemical fertilizers on the farm. As yet, there is no good fix for the second problem, unless you count irradiation and Haccp plans and overcooking your burgers and, now, staying away from spinach. All of these solutions treat E. coli 0157:H7 as an unavoidable fact of life rather than what it is: a fact of industrial agriculture.

But if industrial farming gave us this bug, it is industrial eating that has spread it far and wide. We don’t yet know exactly what happened in the case of the spinach washed and packed by Natural Selection Foods, whether it was contaminated in the field or in the processing plant or if perhaps the sealed bags made a trivial contamination worse. But we do know that a great deal of spinach from a great many fields gets mixed together in the water at that plant, giving microbes from a single field an opportunity to contaminate a vast amount of food. The plant in question washes 26 million servings of salad every week. In effect, we’re washing the whole nation’s salad in one big sink.

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Ecological Management, General, Networks, Vulnerability

Two faces of India: water and wind

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india sanitationIn two recent articles the New York Times has written about different faces of India: environmental crisis and environmental innovation both driven by failures to effectively govern energy and water systems.India’s water management crisis is described in the article In Teeming India, Water Crisis Means Dry Pipes and Foul Sludge. The article focuses on New Delhi and how India’s inequality limits its ability to govern public goods, such as aquifiers, rivers, and even its water system.

The crisis, decades in the making, has grown as fast as India in recent years. A soaring population, the warp-speed sprawl of cities, and a vast and thirsty farm belt have all put new strains on a feeble, ill-kept public water and sanitation network.

The combination has left water all too scarce in some places, contaminated in others and in cursed surfeit for millions who are flooded each year. Today the problems threaten India’s ability to fortify its sagging farms, sustain its economic growth and make its cities healthy and habitable. At stake is not only India’s economic ambition but its very image as the world’s largest democracy.

…New Delhi’s water woes are typical of those of many Indian cities. Nationwide, the urban water distribution network is in such disrepair that no city can provide water from the public tap for more than a few hours a day.

An even bigger problem than demand is disposal. New Delhi can neither quench its thirst, nor adequately get rid of the ever bigger heaps of sewage that it produces. Some 45 percent of the population is not connected to the public sewerage system.

Those issues are amplified nationwide. More than 700 million Indians, or roughly two-thirds of the population, do not have adequate sanitation. Largely for lack of clean water, 2.1 million children under the age of 5 die each year, according to the United Nations.

…

[New Delhi’s] pipe network remains a punctured mess. That means, like most everything else in this country, some people have more than enough, and others too little.

The slums built higgledy-piggledy behind Mrs. Prasher’s neighborhood have no public pipes at all. The Jal Board sends tankers instead. The women here waste their days waiting for water, and its arrival sets off desperate wrestling in the streets.

Kamal Krishnan quit her job for the sake of securing her share. Five days a week, she would clean offices in the next neighborhood. Five nights a week, she would go home to find no water at home. The buckets would stand empty. Finally, her husband ordered her to quit. And wait.

“I want to work, but I can’t,” she said glumly. “I go mad waiting for water.”

Elsewhere, in the central city, where the nation’s top politicians have their official homes, the average daily water supply is three times what finally arrives even in Mrs. Prasher’s neighborhood.

The same public failings have also lead to an unexpected wind power boom in India. This boom, lead by Suzlon Energy, is described in The Ascent of Wind Power.

Not even on the list of the world’s top 10 wind-turbine manufacturers as recently as 2002, Suzlon passed Siemens of Germany last year to become the fifth-largest producer by installed megawatts of capacity. It still trails the market leader, Vestas Wind Systems of Denmark, as well as General Electric, Enercon of Germany and Gamesa Tecnológica of Spain.
Suzlon’s past shows how a company can prosper by tackling the special needs of a developing country. Its present suggests a way of serving expanding energy needs without relying quite so much on coal, the fastest-growth fossil fuel now but also the most polluting.
…

Roughly 70 percent of the demand for wind turbines in India comes from industrial users seeking alternatives to relying on the grid, said Tulsi R. Tanti, Suzlon’s managing director. The rest of the purchases are made by a small group of wealthy families in India, for whom the tax breaks for wind turbines are attractive.

…

The demand for wind turbines has particularly accelerated in India, where installations rose nearly 48 percent last year, and in China, where they rose 65 percent, although from a lower base. Wind farms are starting to dot the coastline of east-central China and the southern tip of India, as well as scattered mesas and hills across central India and even Inner Mongolia.

WorldChanging also comments on wind power in India.

Ecological Management, General, New Orleans, Reorganization

Mississippi meanders

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NASA’s Earth Observation newsroom presents satelite images to go with the geological map of Mississippi Meanders used to make the top image of this blog.

NASA EOS image

NASA explains:

As it winds from Minnesota to the Gulf of Mexico, the Mississippi River is in constant flux. Fast water carries sediment while slow water deposits it. Soft riverbanks are continuously eroded. Floods occasionally spread across the wide, shallow valley that flanks the river, and new channels are left behind when the water recedes. This history of change is recorded in the Geological Investigation of the Alluvial Valley of the Lower Mississippi River, published by the Army Corps of Engineers in 1944.

This map of an area just north of the Atchafalaya River shows a slice of the complex history of the Mississippi. The modern river course is superimposed on channels from 1880 (green), 1820 (red), and 1765 (blue). Even earlier, prehistoric channels underlie the more recent patterns. An oxbow lake—a crescent of water left behind when a meander (bend in the river) closes itself off—remains from 1785. A satellite image from 1999 shows the current course of the river and the old oxbow lake. Despite modern human-made changes to the landscape, traces of the past remain, with roads and fields following the contours of past channels.

In the twentieth century, the rate of change on the Mississippi slowed. Levees now prevent the river from jumping its banks so often. The levees protect towns, farms, and roads near the banks of the river and maintain established shipping routes and ports in the Gulf of Mexico. The human engineering of the lower Mississippi has been so extensive that a natural migration of the Mississippi delta from its present location to the Atchafalaya River to the west was halted in the early 1960s by an Army Corps of Engineers project known as the Old River Control Structure (visible in the full-size Landsat image).

The delta switching has occurred every 1,000 years or so in the past. As sediment accumulates in the main channel, the elevation increases, and the channel becomes more shallow and meandering. Eventually the river finds a shorter, steeper descent to the Gulf. In the 1950s, engineers noticed that the river’s present channel was on the verge of shifting westward to the Atchafalaya River, which would have become the new route to the Gulf. Because of the industry and other development that depended on the present river course, the U.S. Congress authorized the construction of the Old River Control Structure to prevent the shift from happening.

For some related reading, John McPhee discusses the Old River Control Structure and US Army Corps attempts to regulate the Mississippi in his great 1989 book the Control of Nature. John Barry provides a history of the regulation of the Mississippi in his book Rising tide: the great Mississippi flood of 1927 and how it changed America.

I previously wrote about the ecology of the Mississippi, Michael Grunwald has an article in Grist Rotten to the Corps arguing that the Corps is behind New Orleans destruction, and wikipedia has an article about levee failures in New Orleans.

Ecological Economics, Ecological Management, General

Low input agriculture as a tool for poverty alleviation

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In many places around the world farmers are discovering that lower input (of fertilizers and pesticides) agriculture can be more profitable, and lower risk, than conventional high input alternatives.

Ethan Apri on NextBillion.net points to an  Asia Times article Turkey’s born-again farmer about Nazmi Ilicali, a farmer in Eastern Turkey who promotes organic agriculture to reduce rural poverty. The region grows organic wheat, rye, barley, white beans, green lentils, chickpeas and bulgur wheat and promotes itself and organizes sales via www.daphan.org. In the article Ilicali explains why and how he promotes organic agriculture:

He explains why, ironically, the poverty of this area makes it perfect for starting organic farming projects: “The earth in this area is especially suitable, because the local population is so poor that for years they have been unable to afford chemical fertilizers. The climate is good for organic agriculture, too. The frost and cold here even kill the eggs laid in the earth by insects, and because of that there is no need for pesticides – we have a totally chemical-free soil.”

Soon after joining the Daphan project, Nazmi took a further step. “After doing extensive research, I decided that organic agriculture was the only investment with good potential in the east of Turkey. But I also knew that any efforts would have to be made in an organized way. When I first became involved three years ago, I brought 633 farmers together, and the European Community gave me the financial support to set up the Eastern Anatolian Farmers and Livestock Keepers Union. Now we have 3,000 members, and are still gathering members like an avalanche gathers snow.”
…

Nazmi explains that when they first started, the biggest problem they had was the packaging and processing of their organic products. Rather than allowing this to stall their progress, they built a small factory and made every member of the association a shareholder. The factory began to grind their own cereals into flour and package it. Their brand identity, sales and profit margins have all improved since.

This experience is placed in a broader context by Bill McKibben. In April 2005 he had a good rich article The Cuba Diet, about Cuba’s semi-successful, involuntary transition to low-input organic agriculture in Harper’s magazine . To put Cuba’s unusual agricultural system (McKibben calls it something like high fedualism) in context he talks to Jules Pretty about other alternative agriculture systems around the world:

… strict organic agriculture isn’t what the Cubans practice (remember those pesticides for the potato bugs). “If you’re going to grow irrigated rice, you’ll almost always need some fertilizer,” said Jules Pretty, a professor at the University of Essex’s Department of Biological Sciences, who has looked at sustainable agriculture in fields around the world. “The problem is being judicious and careful.” It’s very clear, he added, “that Cuba is not an anomaly. All around the world small-scale successes are being scaled up to regional level.” Farmers in northeast Thailand, for instance, suffered when their rice markets disappeared in the Asian financial crisis of the late 1990s. “They’d borrowed money to invest in ‘modern agriculture,’ but they couldn’t get the price they needed. A movement emerged, farmers saying, ‘Maybe we should just concentrate on local markets, and not grow for Bangkok, not for other countries.’ They’ve started using a wide range of sustainability approaches—polyculture, tree crops and agroforestry, fish ponds. One hundred and fifty thousand farmers have made the shift in the last three years.”

Almost certainly, he said, such schemes are as productive as the monocultures they replaced. “Rice production goes down, but the production of all sorts of other things, like leafy vegetables, goes up.” And simply cutting way down on the costs of pesticides turns many bankrupt peasants solvent. “The farmer field schools began in Indonesia, with rice growers showing one another how to manage their paddies to look after beneficial insects,” just the kinds of predators the Cubans were growing in their low-tech labs. “There’s been a huge decrease in costs and not much of a change in yields.”

See also Elena Bennet’s Resilience Science post on Ecological synergisms in agriculture.

Ecological Management, Greenlash

Complicated ecological tradeoffs from water & agriculture

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A recent paper in Water Resources Research (2006: 42) by Eloise Kendy and John Bredehoeft Transient effects of groundwater pumping and surface-water-irrigation returns on streamflow shows how a long history of excess irrigation in the US west has prodcued streamflow that ecosystems and people have come to rely upon. Now improvements in irrigation effectiveness (i.e. more crop per drop) could reduce this streamflow. These connections show how complicated tradeoffs between different water uses can become. Fortunately, in this case, as in many others, it appears that more sophisticated water management can reduce the intensity of this tradeoff.

Abstract: In surface-water-irrigated western valleys, groundwater discharge from excess irrigation sustains winter streamflow at levels that exceed natural flows. This unnatural condition has persisted for so long that hydrologists, water managers, and water users consider it to be normal. Changing land uses and irrigation practices complicate efforts to manage groundwater discharge and, in turn, to protect instream flows. We examined the impacts on streamflow of (1) seasonal groundwater pumping at various distances from the Gallatin River and (2) improving irrigation efficiency in the Gallatin Valley, Montana. We show that the greater the distance from a seasonally pumping well to a stream, the less the stream depletion fluctuates seasonally and the greater the proportion of annual depletion occurs during the nonirrigation season. Furthermore, we show that increasing irrigation efficiency has implications beyond simply reducing diversions. Improving irrigation efficiency reduces fall and winter flows to a lower, but more natural condition than the artificially high conditions to which we have become accustomed. However, existing water users and aquatic ecosystems may rely upon return flows from inefficient irrigation systems. By strategically timing and locating artificial recharge within a basin, groundwater and surface water may be managed conjunctively to help maintain desirable streamflow conditions as land uses and irrigation practices change.

Eloise Kendy has a short related article in Geotimes (June 2005) Water woes: predictable but not inevitable, where she writes how land-use change produces inadvertent ecological engineering that should become more intentional and less haphazard.

The change from irrigated agriculture to residential development entails more than simply pumping groundwater. Most irrigation systems in the West — especially the oldest systems on the most productive ground — use diverted surface water. Irrigation water that crops do not use seeps into the soil and eventually reaches the water table, where it recharges groundwater in the underlying aquifer. So-called irrigation return flow is a major source of groundwater recharge in irrigated western valleys.

The irrigation-charged groundwater slowly makes its way underground to rivers, streams and springs, where it eventually discharges. Groundwater discharge from irrigation return flow keeps rivers flowing well into late summer and fall, even after all the snow has long since melted, even after the rains have stopped. Although not a natural phenomenon, we consider this annual flow pattern “normal,” for it has recurred for more than 30 years.

The most important hydrologic change brought on by urban and suburban development is a drastic reduction in groundwater recharge. Urban land surfaces such as roofs, roads and parking lots are impermeable. Rain and snowmelt run off these surfaces, instead of seeping into the ground and recharging aquifers. In a typical engineering design, runoff is quickly shunted into the nearest stream or river to rid the area of potential flood waters. Consequently, localized recharge greatly decreases, streamflow becomes “flashier” (larger fluctuations over shorter periods of time), and late-season, groundwater-fed streamflow decreases. When irrigation stops, seepage from excess irrigation water also stops, or continues to recharge the aquifer only from leaky ditches.

Almost without exception, rural residential development in the West relies on well water for domestic use. So, on top of reducing aquifer recharge, the change from surface-water-irrigated cropland to groundwater-irrigated yards increases aquifer discharge. Less water goes into the aquifer than before, and more water goes out.

Previously, irrigation diversions depleted streamflow in the spring and early summer, and irrigation return flow maintained streamflow well into the late summer and fall. Now, with fewer surface-water diversions, early flows increase, as does the risk of flooding. Conversely, late-season flows decrease, potentially leaving fish and downstream irrigators high and dry.

…

When sewers were put in place in Long Island, N.Y., in the 1950s, wastewater that previously recharged the aquifer now discharges straight into the ocean. The loss of aquifer recharge caused the water table to drop about 20 feet. To save the aquifer, more than 3,000 small recharge basins were constructed. Their average combined infiltration rate of 150 millions gallons per day has successfully reversed the trend of declining water levels in the aquifer.

Out West, many creative options exist for water management. Most of the basins within the Basin and Range province, which, loosely defined, extends from Canada to Mexico, provide ideal geologic settings for storing artificially recharged water underground. Using existing irrigation infrastructure, we could spread spring runoff onto benchlands, allowing it to flow underground toward rivers, where it would replace irrigation return flow as a resource for late-season use. Another simple option is to discourage landscaping that requires irrigation.

via Kevin Vranes’s No Se Nada.

Ecological Management, Regime Shifts, Vulnerability

Does Rainfall Increase in the Sahel Mask a Degradation Trend?

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There have been heated debates about the dynamics of land degradation and climate change in the Sahel region in West Africa. The region has suffered a number of extreme droughts since the 1960’s causing famine, loss of livestock and reduced vegetation. However, a ‘greening trend’ trend has recently been detected. To a large extent this trend appears to be driven by increased rainfall (although some scientists argue that this alone can not explain the full extent of the greening trend).

Several studies, based on remote sensing, have now analyzed the reduced vegetation during the drought years and compared it to current land cover. Interestingly, they have not detected any land degradation that can be attributed to land management, which is in contrast with earlier studies suggesting that livestock management in the region is reducing productivity and increasing the systems vulnerability to drought.

A recent paper ‘Desertification in the Sahel: a reinterpretation’ by Hein and De Ridder published in Global Change Biology, suggests that the analyses based on remote sensing may be flawed and that land degradation may have been masked by rainfall.

Hein and De Ridder’s reasoning builds on the way that previous studies linked net primary production (NPP) (or actually a vegetation index – NDVI) to rainfall. These previous studies assumed that for a given site with no land degradation a linear relationship exists between NPP and rainfall (i.e. the Rain Use Efficiency (RUE) is constant). When they did not see any change in RUE over time they assumed that there has not been any land degradation.

Hein and De Ridder studied RUE in six field sites and found that in the absence of land degradation the relationship between NPP and rainfall was non-linear (followed a quadratic curve). When they looked at expected RUE values based on their quadratic estimates they found that the RUE from satellite estimates were lower than the expected ones, and thus land degradation may have occurred. They conclude:

If anthropogenic degradation of the Sahel is demonstrated, this would have repercussions for the debate on the causes of climate change in the Sahel. Currently, a weakness in the argumentations … that anthropogenic land cover changes have contributed to the occurrence of the extreme Sahelian droughts of the last decades of the 20th century is a lack of evidence of degradation from remote sensing data. Hence, if new remote sensing analyses confirm anthropogenic degradation, this would support the hypothesis that degradation of the vegetation layer, in particular through sustained high grazing pressures, has contributed to the occurrence of the 20th century droughts in the Sahel. Furthermore, if degradation of the Sahelian vegetation cover is confirmed, this would indicate that Sahelian pastoralists may be more vulnerable for future droughts than currently assumed. Because degradation of the Sahel in the 1980s and 1990s has been masked by an upward trend in annual rainfall, the consequences of a future drought for the local population could be unexpectedly severe.