Category Archives: Vulnerability

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.

Visualization, Vulnerability

Mapping global soil degradation

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UNEP global map of soil degradation

UNEP provides access to a number of global environmental datasets via the GEO data portal. For example, the Global Assessment of Human Induced Soil Degradation data base was created in 1990 by ISRIC. The database contains information on soil degradation within map units reported by a survey of soil experts from around the world. It includes the type, degree, extent, cause and rate of soil degradation.
The main causes of degradation are (in order) overgrazing, deforestation, and agricultural mismanagement. Each of these is responsible for a bit less than a third of total degraded area. Other causes of degradation make up less than 8% of the total degraded area. Deforestation dominates in Asia, while overgrazing is the main driver in Africa and Australia.
For details of assessment see:

Oldeman LR, Hakkeling RTA and Sombroek WG 1991. World Map of the Status of Human-Induced Soil Degradation: An explanatory Note (rev. ed.), UNEP and ISRIC, Wageningen pdf

Ecological Economics, Ideas, New Orleans, Reorganization, Vulnerability

Hurricanes, Risk Models, and Insurance

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Roger Pielke Jr has an interesting post Are We Seeing the End of Hurricane Insurability? on the Prometheus weblog. The insurance industry uses models of expected losses to set rates for catastrophic losses – from things such as huricanes. However, the models that are properitarity and not open to public evaluation. Now consumer groups are attacking the providers of “catastrophe models” arguing that these models main purpose is to justify increases in insurance rates.

In the past consumer groups have argued:

Consumers were told that, after the big price increases in the wake of Hurricane Andrew, they would see price stability. This was because the projections were not based on short-term weather history, as they had been in the past, but on very long-term data from 10,000 to 100,000 years of projected experience. The rate requests at the time were based upon the average of these long-range projections. Decades with no hurricane activity were assessed in the projections as were decades of severe hurricane activity, as most weather experts agree we are experiencing now. Small storms predominated, but there were projections of huge, category 5 hurricanes hitting Miami or New York as well, causing hundreds of billions of dollars in damage. Consumers were assured that, although hurricane activity was cyclical, they would not see significant price decreases during periods of little or no hurricane activity, nor price increases during periods of frequent activity. That promise has now been broken.

While the catastrophe modelling firms argue:

Given a constant climatological state (or if annual variations from that state are short lived and unpredictable) the activity rate in a catastrophe model can best be represented as the average of long-term history. In this situation there is no need to characterize the period over which the activity is considered to apply because, with current knowledge, it is expected that rate will continue indefinitely. The assumption that activity remains consistent breaks down, however, where there are either multi-year fluctuations in activity or persistent trends. It then becomes necessary to characterize the time period over which the activity in the Cat model is intended to apply.

Pielke argues that the disaster modellers are implying

…that the historical climatology of hurricane activity is no longer a valid basis for estimating future risks. This means that the catastrophe models that they provide are untethered from experience. Imagine if you are playing a game of poker, and the dealer tells you that the composition of the deck has been completely changed – now you don’t know whether there are 4 aces in the deck or 20. It would make gambling based on probabilities a pretty dodgy exercise. If RMS [Risk Management Solutions – a catastrophe modelling company] is correct, then it has planted the seed that has potential to completely transform its business and the modern insurance and reinsurance industries.

What happens if history is no longer a guide to the future? One answer is that you set your expectations about the future based on factors other than experience. One such approach is to ask the relevant experts what they expect. This is what RMS did last fall, convening Kerry Emanuel, Tom Knutson, Jim Elsner, and Mark Saunders in order to conduct an “expert elicitation”.

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… RMS conducted its elicitation October, 2005 with the intent that it will shape its risk estimates for the next 5 years. This is wholly unrealistic in such a fast moving area of science. It is unlikely that the perspectives elicited from these 4 scientists will characterize the views of the relevant community (or even their own views!) over the next five years as further research is published and hurricane seasons unfold. Because RMS has changed from a historical approach to defining risk, which changes very, very slowly, if at all over time, to an expert-focused approach, it should fully expect to see very large changes in expert views as science evolves. This is a recipe for price instability, exactly the opposite from what the consumer groups, and insurance commissioners, want.

From the perspective of the basic functioning of the insurance and reinsurance industries, the change in approach by RMS is an admission that the future is far more uncertain than has been the norm for this community. Such uncertainty may call into question the very basis of hurricane insurance and reinsurance which lies in an ability to quantify and anticipate risks. If the industry can’t anticipate risks, or simply come to a consensus on how to calculate risks (even if inaccurate), then this removes one of the key characteristics of successful insurance. Debate on this issue has only just begun.

Hedging ones bets with insurance is a good strategy to deal with risk – where known outcomes are expected to occur with some known probability. However, when confronting more uncertain situations other approaches such as building resilience to potential classes of shock, engaging in experimental management to decrease uncertainty, and accelerating learning by integrating sources of knowledge across a wider variety of domains (e.g. meterology, ecology, and urban planning) and different regions (e.g. Sri Lanka, the Netherlands, and New Orleans).

Ideas, Regime Shifts, Reorganization, Vulnerability

Exploring Resilience in Social-Ecological Systems – E&S special feature

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Ecology & Society has just published a special feature Exploring Resilience in Social-Ecological Systems: Comparative Studies and Theory Development based upon the comparisons of 15 Resilience Alliance case studies.

The current table of contents of the issue is:

Exploring Resilience in Social-Ecological Systems Through Comparative Studies and Theory Development: Introduction to the Special Issue
by Brian H. Walker, John M. Anderies, Ann P. Kinzig, and Paul Ryan

A Handful of Heuristics and Some Propositions for Understanding Resilience in Social-Ecological Systems
by Brian Walker, Lance Gunderson, Ann Kinzig, Carl Folke, Steve Carpenter, and Lisen Schultz

Scale Mismatches in Social-Ecological Systems: Causes, Consequences, and Solutions
by Graeme S. Cumming, David H. M. Cumming, and Charles L. Redman

Resilience and Regime Shifts: Assessing Cascading Effects
by Ann P. Kinzig, Paul Ryan, Michel Etienne, Helen Allyson, Thomas Elmqvist, and Brian H. Walker

Fifteen Weddings and a Funeral: Case Studies and Resilience-based Management
by John M. Anderies, Brian H. Walker, and Ann P. Kinzig

Toward a Network Perspective of the Study of Resilience in Social-Ecological Systems
by Marco A. Janssen, Örjan Bodin, John M. Anderies, Thomas Elmqvist, Henrik Ernstson, Ryan R. J. McAllister, Per Olsson, and Paul Ryan

Collapse and Reorganization in Social-Ecological Systems: Questions, Some Ideas, and Policy Implications
by Nick Abel, David H. M. Cumming, and John M. Anderies

Governance and the Capacity to Manage Resilience in Regional Social-Ecological Systems
by Louis Lebel, John M. Anderies, Bruce Campbell, Carl Folke, Steve Hatfield-Dodds, Terry P. Hughes, and James Wilson

Water RATs (Resilience, Adaptability, and Transformability) in Lake and Wetland Social-Ecological Systems
by Lance H. Gunderson, Steve R. Carpenter, Carl Folke, Per Olsson, and Garry Peterson

Shooting the Rapids: Navigating Transitions to Adaptive Governance of Social-Ecological Systems
by Per Olsson, Lance H. Gunderson, Steve R. Carpenter, Paul Ryan, Louis Lebel, Carl Folke, and C. S. Holling

Greenlash, Ideas, New Orleans, Tools, Visualization, Vulnerability

Mapping Sea Level Rise

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Sea Level Rise Jonathan Overpeck and others have a paper Paleoclimatic Evidence for Future Ice-Sheet Instability and Rapid Sea-Level Rise in Science (24 March 2006) that suggests that sea level rise due to anthropogenic climate change could occur much faster than people have previously expected. Possibly an increase of 5 to 10 m of several centuries. (For news articles see BBC, NYTimes, & Toronto G&M).

To visualize the consquences of sea level rise:

WorldChanging points to Flood Maps. A site that mashes up NASA elevation data with Google Maps, and offers a visualization of the effects of a single meter increase all the way to a 14 meter rise. Some examples are: Vancouver with 6m sea rise, New Orleans, and the Netherlands.

Also, Jonathan Overpeck‘s lab also has a visualization of the consquences of sea level rise for the US and the world.

Richard Kerr writes in a news article in Science, A Worrying Trend of Less Ice, Higher Seas:

The ice sheet problem today very much resembles the ozone problem of the early 1980s, before researchers recognized the Antarctic ozone hole, Oppenheimer and Alley have written. The stakes are high in both cases, and the uncertainties are large. Chemists had shown that chlorine gas would, in theory, destroy ozone, but no ozone destruction had yet been seen in the atmosphere. While the magnitude of the problem remained uncertain, only a few countries restricted the use of chlorofluorocarbons, mainly by banning their use in aerosol sprays.

But then the ozone hole showed up, and scientists soon realized a second, far more powerful loss mechanism was operating in the stratosphere; the solid surfaces of ice cloud particles were accelerating the destruction of ozone by chlorine. Far more drastic measures than banning aerosols would be required to handle the problem.

Now glaciologists have a second mechanism for the loss of ice: accelerated flow of the ice itself, not just its meltwater, to the sea. “In the end, ice dynamics is going to win out” over simple, slower melting, says Bindschadler. Is glacier acceleration the ozone hole of sea level rise? No one knows. No one knows whether the exceptionally strong warmings around the ice will continue apace, whether the ice accelerations of recent years will slow as the ice sheets adjust to the new warmth, or whether more glaciers will fall prey to the warmth. No one knows, yet.

Ideas, New Orleans, Reorganization, Vulnerability

Ruin and Recovery

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Ruin & Recovery is a special series of newspaper articles in the New Orleans Times-Picayune on how other cities responded to disasters:

  • Galveston, TX – Galveston almost went under in the hurricane of 1900, but city leaders saved it, and a new economy reshaped it.
  • Charleston, SC – Historic Charleston survived Hurricane Hugo and rebuilt, keeping its charm
  • Grand Forks, ND – Lessons learned after devastating floods in 1997
  • Homestead, FL – Hurricane Andrew nearly wiped Homestead off the map. But after early stumbles, and a lot of help from private enterprise, the town is stronger than ever
  • Kobe, Japan – In seconds, buildings collapsed, bridges toppled and thousands died when an earthquake hit Kobe, Japan, 10 years ago. Despair was rampant. But with dogged determination, the city rebuilt, repopulated and rebounded
  • The Netherlands – After a North Sea flood killed nearly 2,000 peole in the Netherlands in 1953, building a state-of-the-art flood defense became a national priority.
Big Back Loop, Ideas, Scenarios, Vulnerability

Planet of Slums

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The prolific and controversial urban critic, Mike Davis, has a new book Planet of Slums. It is based upon his article Planet of Slums in New Left Review (March-April 2004). In Planet of Slums he writes:

There may be more than quarter of a million slums on earth. The five great metropolises of South Asia (Karachi, Mumbai, Delhi, Kolkata and Dhaka) alone contain about 15,000 distinct slum communities with a total population of more than 20 million. An even larger slum population crowds the urbanizing littoral of West Africa, while other huge conurbations of poverty sprawl across Anatolia and the Ethiopian highlands; hug the base of the Andes and the Himalayas; explode outward from the skyscraper cores of Mexico, Jo-burg, Manila and São Paulo; and, of course, line the banks of the rivers Amazon, Niger, Congo, Nile, Tigris, Ganges, Irrawaddy and Mekong. The building blocks of this slum planet, paradoxically, are both utterly interchangeable and spontaneously unique: including the bustees of Kolkata, the chawls and zopadpattis of Mumbai, the katchi abadis of Karachi, the kampungs of Jakarta, the iskwaters of Manila, the shammasas of Khartoum, the umjondolos of Durban, the intra-murios of Rabat, the bidonvilles of Abidjan, the baladis of Cairo, the gecekondus of Ankara, the conventillos of Quito, the favelas of Brazil, the villas miseria of Buenos Aires and the colonias populares of Mexico City. They are the gritty antipodes to the generic fantasy-scapes and residential themeparks—Philip K. Dick’s bourgeois ‘Offworlds’—in which the global middle classes increasingly prefer to cloister themselves.

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Ideas, New Orleans, Vulnerability

Watermark: can southern Louisiana be saved

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New Orleans Flooded after KatrinaElizabeth Kolbert, a writer for the New Yorker, who also wrote a series of articles – Climate of Man – about climate change. Wrote a fairly grim article Watermark: can southern Louisiana be saved, in the Feb 27, 2006 New Yorker. She writes about geology, wetland loss, climate change, and people of New Orleans.

Five thousand years ago, much of southern Louisiana did not exist. A hundred years from now, it is unclear how much of it will remain. The region, it is often observed, is losing land at the rate of a football field every thirty-eight minutes. Alternatively, it is said, the area is shrinking by a large desktop’s worth of ground every second, or a tennis court’s worth every thirteen seconds, or twenty-five square miles a year. Between 1930 and 2000, some 1.2 million acres, an area roughly the size of Delaware, disappeared. Hurricanes Katrina and Rita stripped away an estimated seventy-five thousand acres—a loss as big as Manhattan and Brooklyn combined. The U.S. Geological Survey has published a map illustrating the process. Areas that have already vanished appear in red, and areas that are expected to vanish by 2050 in yellow. On the map, the southern coast looks as if it were on fire. According to the U.S. Army Corps of Engineers, “The rate at which Louisiana’s land is converting to water is probably the fastest in the world. [here is an animated map]

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Ideas, New Orleans, Vulnerability

Recovering New Orleans: the Resilient City

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Thomas J. Campanella, the co-editor The Resilient City: How Modern Cities Recover From Disaster (Oxford University Press, 2005), a professor of urban design and city planning at the University of North Carolina at Chapel Hill, and a visiting lecturer at Nanjing University’s Graduate School of Architecture, wrote about the resilience of cities and New Orleans in Sept 2005 on the urban planning website Planetizen:

Lost cities are in fact a relative historical rarity. True, Atlantis remains unfound, let alone rebuilt. Pompeii and Herculaneum were buried permanently beneath the hot ejecta of Vesuvius in 79AD. Timgad was sacked by both the Vandals and the Berbers and lost to history until archeologists uncovered it in the 1880s. Monte Albán, on the heights above the modern Mexican city of Oaxaca, flourished for 2,000 years before the Spanish crushed it for all time. But these are the exceptions. Much more common in the annals of urban history are cities that have rebounded again and again from even horrific devastation. The Romans leveled Carthage after the Third Punic War, salting it for good measure. But it was the Romans themselves who later resurrected the port city and turned it into an administrative hub for their African possessions; even today Carthage persists as a suburb of Tunis. By about 1800, urban resilience becomes the rule. No major city in the last 200-odd years has been completely destroyed, in spite of humankind’s ever-increasing power to do so. There are only a handful of exceptions; St. Pierre, Martinique — the “Paris of the Antilles” — was annihilated by a volcanic eruption in 1902 and never rebuilt. Only one man survived, and only because he was locked in solitary confinement. But for every St. Pierre, there are a hundred cities that bounced right back from catastrophic destruction.

The subject of urban resilience is one I explored with Lawrence J. Vale in an anthology entitled The Resilient City: How Modern Cities Recover From Disaster (Oxford, 2005). Our comparative study revealed no short answers as to why urban sites in the modern age are rarely abandoned (factors such as embedded infrastructure, private property rights and insurance, even the political symbolism of reconstruction for a nation have all played a role). Our study did yield, however, a number of key points and common themes about both disasters and urban resilience, many of which have gained new relevance in the wake of Hurricane Katrina. For one, cities vary enormously in their resilience. Just as some people can fend off a traumatic illness while others succumb, not all cities are equally capable of rebounding from a shock to the system.

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Ecological Management, General, Vulnerability

Science, good causes, and bad arguements

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Steve Rayner has an editorial in the Feb 2006 issue of Global Environmental Change – What drives environmental policy? about science and public policy. He writes:

Rather than resolving political debate, science often becomes ammunition in partisan squabbling, mobilized selectively by contending sides to bolster their positions. Because science is highly valued as a source of reliable information, disputants look to science to help legitimate their interests. In such cases, the scientific experts on each side of the controversy effectively cancel each other out, and the more powerful political or economic interests prevail, just as they would have without the science. This scenario has played out in almost every environmental controversy of the past 25 years (Sarewitz 2000).

This phenomenon has led to a widespread pathology: the use of bad arguments for good causes.

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