Category Archives: Regime Shifts

Regime Shifts

Reviewing Critical Transitions

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transcoverEnvironmental historian, John R. McNeill, reviews Marten Scheffer‘s new book on resilience – Critical Transitions in Nature and Society. In the American Scientist he writes:

Like many before him, Marten Scheffer is impressed with parallels between social systems and natural systems. Moreover, he is convinced that problems confronting the human race require something more integrated than the fragmentary knowledge of the various academic disciplines. In short, he seeks to span the famous “two cultures” and to take a long stride toward consilience. Coming from a background in limnology and aquatic ecology, Scheffer is inevitably more at home in some arenas of knowledge than others, and his new book, Critical Transitions in Nature and Society, is mainly about the critical transitions in nature that are of interest to society. An example with which he begins the book is typical: the transformation of the Western Sahara into desert about 5,500 years ago as a result of initially small climate change that built on itself because the drier climate reduced vegetation, thereby heightening albedo.

Part of Scheffer’s aim is to contribute to the study of how well the theory of system dynamics corresponds to real life, in the behavior both of nature and of society. “If we are able to pin down the mechanisms at work,” he says, “this may eventually open up the possibility of predicting, preventing, or catalyzing big shifts in nature and society.” To be able to do so is a long-standing human ambition, which has been given fullest rein in political regimes that have seen utopia just over the horizon and have aimed to get there as soon as possible. In the abstract, such ambition seems laudable. In practice, it has led to many regrettable “big shifts” in nature and society, such as those undertaken in the headiest days of the Soviet Union or Mao Zedong’s rule in China. To date, those most keen on provoking “big shifts” have known far too little, and perhaps cared too little as well, about the possible outcomes of their actions. When results did not conform closely enough to their hopes, they used their powers to try to force society and nature into preferred channels, which led to gulags and environmental disasters. When trying to catalyze big shifts in nature and society, one must really know what one is doing—and that is very, very hard to do.

…

So Scheffer seems more cheerful about the future of the Social-Eco-Earth-System at the end of writing his book than I am after reading it. But his premise—that hope lies with integrated eco-social science rather than our traditional isolated silos of knowledge—is surely correct. Perhaps we are on the edge of a happy tipping point after which science enters a state in which depth is not unduly esteemed over breadth, in which integrated study of complex systems becomes the norm, in which our insight into real-world eco-social systems grows and grows to formerly unimaginable levels. If so, Scheffer may be right to be optimistic. But there are some powerful attractors working against it.

Big Back Loop, Regime Shifts, Reorganization

Planetary Boundaries

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nature-climate-graphic-225A number of resilience researchers, and many others, have proposed the concept of planetary boundaries in a new paper A safe operating space for humanity in Nature (doi:10.1038/461472a).

Johan Rockstrom and others propose nine planetary boundaries, beyond which the functioning of the earth system will fundamentally change.  They argue that we have crossed the climate, nitrogen and extinction boundaries, and need to change the course of our civilization to move back into  conditions which provide a safety for human civilization.

Nature has a special feature on Planetary Boundaries.  It has also published seven independent essays by experts who reflect upon each of the defined boundary (two of the nine were not defined due to a lack of information), and their blog Climate Feedback is also hosting a discussion of the article.

Science journalist, Carl Zimmer has written a good article about the paper and concept on Yale’s Environment 360.

The Stockholm Resilience Centre provides links to the full paper, and supporting information, as well as a number of videos explaining the concept.

Ecological Management, Regime Shifts

Responses to Early Warning Signals for Critical Transitions paper

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The recent paper by Marten Scheffer and other resilience researchers paper Early Warning Signals for Critical Transitions (doi:10.1038/nature08227) has been reported in a number of places including Time, USA Today, and Wired.  While many newspapers just reprint the press release, several articles add something.

A USA Today article Predicting tipping points before they occur quotes Brian Walker:

“This is a very important paper,” says Brian Walker, a fellow at the Stockholm Resilience Center at the University of Stockholm in Sweden.

“The big question they’re trying to answer is, how the hell do you know when it’s coming? Is there any way you can get an inkling of a looming threshold, something that might be a warning signal that you’re getting to one of the crucial transition points?”

Wired magazine article Scientists Seek Warning Signs for Catastrophic Tipping Points quotes several sceptical scientists:

“It’d be very nice if it were true that there were precursors for tipping points in all these diverse systems. It’d be even nicer if we could find these precursors. I want to believe it, but I’m not sure I do,” said Steven Strogatz, a Cornell University biomathematician who was not involved in the paper.

The difficulty of early detection is especially pronounced with markets. Computer models can replicate their bubble-and-crash behavior, but real markets — buffeted by political and social trends, and inevitably responding to the very act of prediction — are much cloudier.

“It is hard to find clear evidence of bifurcations and transitions, let alone find an early warning system to detect an upcoming crash,” said Cars Homme, an economic theorist at the University of Amsterdam.

The most promising evidence of useful early warning signs comes from grasslands, coral reefs and lakes. Vegetation-pattern-based early warning signs have been documented in several regions, and transition theory is already being used to guide land use in parts of Australia.

The U.S. Geological Survey is currently hunting through satellite imagery for signals of impending desertification at two sites in the Southwest. They’ve studied desertification there by painstakingly measuring local conditions and experimentally setting fires, removing grasses and controlling the fall of water. But so far, the vegetation patterns that indicated tipping points in the Kalahari haven’t shown up here, though this may be due to poor image quality rather than bad theory. The researchers are now looking for signals in on-the-ground measurements of vegetation changes.

“These things aren’t going to be foolproof. There will be false positives and false negatives, and people need to be aware of that,” said Carpenter. “There’s still a great deal of basic research going on to understand the indicators better. We’re still in the early days. But why not try? The alternative is to get repeatedly blindsided. The alternative is not appealing.”

Time magazine in Is There a Climate-Change Tipping Point? quotes co-author Steve Carpenter:

So, how do we know that change is at hand? The Nature researchers noticed one potential signal: the sudden variance between two distinct states within one system, known by the less technical term squealing. In an ecological system like a forest, for example, squealing might look like an alternation between two stable states — barren versus fertile — before a drought takes its final toll on the woodland and transforms it into a desert, at which point even monsoons won’t bring the field back to life. Fish populations seem to collapse suddenly as well — overfishing causes fluctuations in fish stocks until it passes a threshold, at which point there are simply too few fish left to bring back the population, even if fishing completely ceases. And even in financial markets, sudden collapses tend to be preceded by heightened trading volatility — a good sign to pull your money out of the market. “Heart attacks, algae blooms in lakes, epileptic attacks — every one shows this type of change,” says Carpenter. “It’s remarkable.” 

In climate terms, squealing may involve increased variability of the weather — sudden shifts from hot temperatures to colder ones and back again. General instability ensues and, at some point, the center ceases to hold. “Before we reached a climate tipping point we’d expect to see lots of record heat and record cold,” says Carpenter. “Every example of sudden climate change we’ve seen in the historical record was preceded by this sort of squealing.”

The hard part will be putting this new knowledge into action. It’s true that we have a sense of where some of the tipping points for climate change might lie — the loss of Arctic sea ice, or the release of methane from the melting permafrost of Siberia. But that knowledge is still incomplete, even as the world comes together to try, finally, to address the threat collectively. “Managing the environment is like driving a foggy road at night by a cliff,” says Carpenter. “You know it’s there, but you don’t know where exactly.” The warning signs give us an idea of where that cliff might be — but we’ll need to pay attention.

Regime Shifts, Vulnerability

Dead Ahead: Similar Early Warning Signals of Change in Climate, Ecosystems, Financial Markets, Human Health

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What do abrupt changes in ocean circulation and Earth’s climate, shifts in wildlife populations and ecosystems, the global finance market and its system-wide crashes, and asthma attacks and epileptic seizures have in common?

According to a paper published this week in the journal Nature, all share generic early-warning signals that indicate a critical threshold of change dead ahead. Cheryl Dybas writing for NSF.gov covers a new paper on “Early Warning Signals for Critical Transitions” (Nature, 3 Sept 2009, 461: 53-59).

In the paper, Martin Scheffer of Wageningen University in The Netherlands and co-authors found that similar symptoms occur in many systems as they approach a critical state of transition.

“It’s increasingly clear that many complex systems have critical thresholds–‘tipping points’–at which these systems shift abruptly from one state to another,” write the scientists in their paper.

Especially relevant, they discovered, is that “catastrophic bifurcations,” a diverging of the ways, propel a system toward a new state once a certain threshold is exceeded.

Like Robert Frost’s well-known poem about two paths diverging in a wood, a system follows a trail for so long, then often comes to a switchpoint at which it will strike out in a completely new direction.

That system may be as tiny as the alveoli in human lungs or as large as global climate.

“These are compelling insights into the transitions in human and natural systems,” says Henry Gholz, program director in the National Science Foundation (NSF)’s Division of Environmental Biology, which supported the research along with NSF’s Division of Ocean Sciences.

“The information comes at a critical time–a time when Earth’s and, our fragility, have been highlighted by global financial collapses, debates over health care reform, and concern about rapid change in climate and ecological systems.”

It all comes down to what scientists call “squealing,” or “variance amplification near critical points,” when a system moves back and forth between two states.

“A system may shift permanently to an altered state if an underlying slow change in conditions persists, moving it to a new situation,” says Carpenter.

Eutrophication in lakes, shifts in climate, and epileptic seizures all are preceded by squealing.

Squealing, for example, announced the impending abrupt end of Earth’s Younger Dryas cold period some 12,000 years ago, the scientists believe. The later part of this episode alternated between a cold mode and a warm mode. The Younger Dryas eventually ended in a sharp shift to the relatively warm and stable conditions of the Holocene epoch.

The increasing climate variability of recent times, state the paper’s authors, may be interpreted as a signal that the near-term future could bring a transition from glacial and interglacial oscillations to a new state–one with permanent Northern Hemisphere glaciation in Earth’s mid-latitudes.

In ecology, stable states separated by critical thresholds of change occur in ecosystems from rangelands to oceans, says Carpenter.

The way in which plants stop growing during a drought is an example. At a certain point, fields become deserts, and no amount of rain will bring vegetation back to life. Before this transition, plant life peters out, disappearing in patches until nothing but dry-as-bones land is left.

Early-warning signals are also found in exploited fish stocks. Harvesting leads to increased fluctuations in fish populations. Fish are eventually driven toward a transition to a cyclic or chaotic state.

Humans aren’t exempt from abrupt transitions. Epileptic seizures and asthma attacks are cases in point. Our lungs can show a pattern of bronchoconstriction that may be the prelude to dangerous respiratory failure, and which resembles the pattern of collapsing land vegetation during a drought.

Epileptic seizures happen when neighboring neural cells all start firing in synchrony. Minutes before a seizure, a certain variance occurs in the electrical signals recorded in an EEG.

Shifts in financial markets also have early warnings. Stock market events are heralded by increased trading volatility. Correlation among returns to stocks in a falling market and patterns in options prices may serve as early-warning indicators.

“In systems in which we can observe transitions repeatedly,” write the scientists, “such as lakes, ranges or fields, and such as human physiology, we may discover where the thresholds are.

“If we have reason to suspect the possibility of a critical transition, early-warning signals may be a significant step forward in judging whether the probability of an event is increasing.”

Co-authors of the paper are William Brock and Steve Carpenter of the University of Wisconsin-Madison, Jordi Bascompte and Egbert van Nes of the Consejo Superior de Investigaciones Scientificas, Sevilla, Spain; Victor Brovkin of the Max Planck Institute for Meteorology in Hamburg, Germany; Vasilis Dakos of the Potsdam Institute for Climate Research in Potsdam, Germany; Max Rietkerk of Utrecht University in The Netherlands; and George Sugihara of Scripps Institution of Oceanography in California.

The research was funded by the Institute Para Limes and the South American Institute for Resilience and Sustainability Studies, as well as the Netherlands Organization of Scientific Research, the European Science Foundation, and the U.S. National Science Foundation, among others.

Big Back Loop, Greenlash, Regime Shifts

Lovelock, climatic regime shifts, and soft sociology

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In Nature, biogeochemist Andrew Watson reviews The Vanishing Face Of Gaia by James Lovelock in Final warning from a sceptical prophet:

In The Vanishing Face Of Gaia, Lovelock argues that model projections of the climate a century ahead are of little use. The models of the Intergovernmental Panel on Climate Change (IPCC) extrapolate from a smooth trend of warming, yet the real climate system, complex and fully coupled to the biology of land and ocean, is unlikely to change in this simple way. It is more likely to flip from one state to another, with non-linear tipping points that the IPCC models are too simplistic to capture. Lovelock fears that the climate will shift to a new and considerably hotter regime, and that once underway, this shift will be irreversible.

This view is not officially sanctioned ‘IPCC-speak’, but he is fully within the envelope of scientific consensus when he warns of the possibility of rapid and irreversible change. Other climate scientists — notably Wally Broecker (see Nature 328, 123–126; 1987) — have said much the same for a long time, although Lovelock uses more graphic language and his popular voice will carry further. Palaeoclimate records show that rapid flips have happened before, so this must be a strong possibility for the future if we continue to force up the levels of greenhouse gases at the current rate.

What is controversial is Lovelock’s vision for humanity: rapid climate change will lead to the deaths of most people on the planet, and to mass migrations to those places that are still habitable. He does not spell out exactly how this might happen, but is convinced a hotter Earth will be able to sustain only a few per cent of the current human population. The implication is that Gaia and human society are close to a cliff-edge, and could unravel rapidly and catastrophically.

The controversy lies less in the climatology and more in the sociology. How will societies behave in the face of such change? Will we pull together with a wartime spirit, or will we fragment, fight and kill one another over Gaia’s carcass? Lovelock is on softer ground here. His only special qualification for discussing human behaviour is his longevity — having lived through the Second World War, he knows what people sometimes do to one another during evil times.

Lovelock’s vision of sudden and imminent collapse is apocalyptic, but for our long-term future and that of the planet it might be preferable to some of the alternatives. Suppose, for instance, that our profligate ways and expanding population are sustained for the rest of this century, but at a huge cost — the complete loss of all the natural ecosystems of the world. Most of us, living in cities and insulated from the natural environment, would barely notice until it was too late to do anything about it. This is what many politicians, economists and industrialists seem to want — their mantra of unceasing economic growth implies that we should take for ourselves all Gaia’s resources and squeeze from them the maximum short-term gain, leaving nothing for the future.

Following this vision, we will need to transform the entire planet into a factory farm to feed our 10 billion or 15 billion mouths. There will be no room on this giant spherical feedlot for anything but ourselves and our half-dozen species of domestic plants and animals. Gaia, the natural Earth system, will have disappeared. As for the underpinning biogeochemical cycles, the best we can hope is that we can manage them ourselves, taking over the heavy responsibility for keeping Earth habitable, which Gaia once did for us automatically.

The more likely outcome is that we would barely manage them at all. In that case, we would face a sequence of global environmental crises and a steady degradation of the planetary environment that would eventually kill just as many of us as a sudden collapse. Given that, perhaps we had better hope that Lovelock is right, and Gaia does for us — or most of us — before we do for her.

General, Regime Shifts

Caribbean reef fish decline in wake of coral collapse

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A recent paper by Paddack et al in Current Biology (doi:10.1016/j.cub.2009.02.041) that shows that observed declines in fish populations in the Caribbean are  consistent across all subregions of the Caribbean basin (2.7% to 6.0% loss per year) and appear to be linked to coral reef collapse.  In Science Jackie Grom reports on the paper in Reef Fish Threatened by Coral Loss:

Ecologist Michelle Paddack, a postdoctoral student at Simon Fraser University in Burnaby, Canada, teamed up with an international group of scientists to find out. They analyzed data from 48 studies, including peer-reviewed papers, government and university research reports, and unpublished data sets, that covered trends on 318 Caribbean coral reefs and 273 species of reef fish over a 53-year period. Today in Current Biology, the team reports that reef fish populations were relatively constant from 1955 through 1995 but then plunged by about 3% to 6% each year through 2007. The declines occurred in three of six dietary groups, including those that fed primarily on algae, invertebrates, or a combination of fish and invertebrates. The loss of algae-eating fish, such as parrotfish and surgeonfish, is worrying, says Paddack, because they help the reefs thrive by clearing away algae.

The declines don’t appear to be caused by overfishing, because the losses were similar for fished and nonfished species. Paddack says that doesn’t mean fishing doesn’t have an impact but that something even bigger is influencing the entire sea. The researchers suggest that the culprit is unprecedented loss of coral reefs over the past 3 decades. Even though the reduction in fish populations lags nearly 20 years behind the coral loss, the consistency in fish declines across a wide range of species points to the loss of coral as the cause, they say.

“We’ve known that corals are declining and fish are declining, but boy, I think it’s powerful just to see the patterns at the regional scale,” says marine ecologist John Bruno of the University of North Carolina, Chapel Hill. Biologist Richard Aronson of the Florida Institute of Technology in Melbourne says that the suggestion that coral reef loss is behind the declines in reef fish is intriguing. But to nail down the link, he’s hoping to see studies that relate fish declines to the time it takes for the reefs to structurally deteriorate after they die. “I liked this paper a lot; it got me excited [about coral reefs] all over again,” he says.

Regime Shifts

Arctic sea ice begins its annual melt with less old ice

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Arctic Sea Ice News & Analysis from the USA’s National Snow and Ice Data Center reports:

Arctic sea ice extent has begun its seasonal decline towards the September minimum. Ice extent through the winter was similar to that of recent years, but lower than the 1979 to 2000 average. More importantly, the melt season has begun with a substantial amount of thin first-year ice, which is vulnerable to summer melt.

Arctic sea ice extent from: National Snow and Ice Data Center

Arctic sea ice extent

Amount of older ice has declined over the recent past: National Snow and Ice Data Center

Amount of older ice has declined over the recent past

Ecological Management, Ideas, Networks, Regime Shifts

Using the internet to provide early warning of ecological change

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It all started with a discussion I had with Resilience Alliance member France Westley a couple of years ago about early warning and response challenges related to epidemic emergencies. Frances recommended I have a look at a lecture by Google’s Larry Brilliant.  A great lecture, and it triggered some new thinking. Maybe there are smart ways to tap into the noise of the Internet, and find early warnings of pending ecological crises? This lead to a first meeting with colleagues at Stockholm University, where we tried to explore the issue. Some were very positive, others very skeptic. The first group moved on with the idea, which is just about to be published in an article Can Webcrawlers revolutionize ecological monitoring in Frontiers in Ecology and the Environment (doi:10.1890/070204).  See also this press release from Stockholm Resilience Centre and an article in Wired.

worldwhiteSo, here is the key message: Sure there is a lot of junk on the Web (just Google for ”Britney Spears” and ”war Darfur”, and compare the number of hits). And people are certainly using emerging social media and Web 2.0 applications – such as Twitter, YouTube, Facebook, Flickr – in ways that seem quite useless from a resilience perspective. But if you look at how the health community is exploring this topic, you are likely to end up much more optimistic. Information and communication technology (ICT) innovations such as GPHIN , Google Flu , and ProMed , has had a tremendous impact on the speed and amount of information that epidemic intelligence can tap into. And nowadays, around 60% of all early warnings of emerging epidemic emergencies that reach the WHO come from these ICT tools. Not bad compared to the failure of conventional epidemic monitoring systems that were based on official data from governments that preferred to keep things to themselves. And that always reported events only after they had escalated out of control.

I’m pretty sure there is a revolution in the pipeline for ecological monitoring if we are smart enough to tap into emerging ICT innovations. Feel free to agree, or disagree by posting your comments on our discussion site.

Regime Shifts

Icehouse to greenhouse tipping points

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icehouseA better understanding of the transition from an ice-free greenhouse to the current glaciated icehouse world suggests that there exist a tipping point dynamics due to hysteresis global ice cover dynamics. Lee Kump reflects on recent research by Liu et al in a the Science Magazine perspective Tipping Pointedly Colder:

For much of Earth history, the climate has been considerably warmer than it is today. But 33.7 million years ago, at the Eocene-Oligocene boundary, the world became trapped in the glacial state that continues to this day. Within just 200,000 years, Antarctica went from being a rather hospitable place to a polar continent buried under kilometers of ice. The transition was abrupt, but also overshot the new equilibrium with a super-glaciation–dubbed the Oi-1 climate event–that lasted a few hundred thousand years.

In an earlier study, Lear et al. (3) found evidence from deep-water sites that there was little if any cooling during the transition. This finding challenged common sense: Surely the planet needs to cool if ice sheets are to grow. Recent work on better preserved shallow-water sites by Lear and colleagues (4) and others (5), together with the results presented by Liu et al. from a geographically diverse suite of locations, shows that cooling did indeed accompany the growth of ice sheets on Antarctica.

…

Simultaneous cooling at high northern and southern latitudes points strongly to a greenhouse gas reduction. It is puzzling, though, that the tropics show little cooling. Climate model simulations, including those conducted by the present authors, cool both tropics and higher latitudes when atmospheric carbon dioxide concentrations are reduced from greenhouse climate conditions.

Using a climate model, Liu et al. can only reproduce the cooling indicated by the temperature proxies when they impose a reduction in atmospheric carbon dioxide concentrations from 8 to 2 times the preindustrial level across the transition. This reduction is much larger than that previously interpreted from atmospheric CO2 proxies, from 4 to 2 times the preindustrial level. If the atmospheric CO2 proxies are correct, then the models are missing something that amplifies the climate sensitivity to changes in atmospheric CO2.

Given the strong evidence that cooling accompanied the transition into the glacial world, the playing out of the onset of Antarctic glaciation follows the script of a tipping-point climate transition. …

In thinking about the future, we must recognize that threshold behavior in one direction–like the Eocene-Oligocene boundary studied by Liu et al.–is normally accompanied by threshold behavior in the reverse direction, although the barriers to transition can differ in size (see the figure). For example, modern climate/ice-sheet models exhibit considerable hysteresis, requiring atmospheric carbon dioxide concentrations to rise well above the original initiation level to melt the Antarctic ice sheet. Future tipping behavior into a warm Eocene-like climate state may thus be delayed, but if and when it does occur, the transition will likely be abrupt.

Regime Shifts

Christian Robert on Black Swans

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Christian Robert, a Bayesian statistican at  Université Paris Dauphine comments on Taleb’s book the Black Swan in his blog article Of black swans and bleak prospects:

… I think that the book can be criticised solely from a statistical point of view as mostly missing the point. For instance, the notions of probable/improbable and randomness [that are constantly in use within the book] are always used in a vague sense and they thus mostly loose their meaning. (The distinction between random—that is, driven by a probability distribution—and fortuitous—that is, lacking any kind of reproducibility to be considered as a probability outcome—comes so late within the book as to be rather useless.) The extreme events that are called black swans are never analysed in terms of model shift, although they mostly correspond to cases where the background model had changed but the players were not aware of it. This somehow gives the impression that the author expects there exists a (deterministic) model that should explain even the most extreme phenomena. When considering some examples in the book like 09/11, this sounds ludicrous: the attack on 09/11 has nothing to do with randomness or a probabilistic model! Similarly, there is no discussion of the possible non-homogeneous nature of the time series leading to black swans.

…It is obviously a difficult exercise to write about popular Science without being populist and it must be almost inevitable to oversimplify one’s discourse by emphasizing a few examples over others, but I think the book overdoes it! By a fair margin. Worse, by attacking modelling tools like the Gaussian, models and modelers as a conglomerate of “charlatans”, it contributes to the anti-Scientist discourse that is unfortunately so prevalent today. Being a skeptic is commendable and scientists should never cease questioning their models, but throwing all models to the winds and using only “facts” to drive one’s decisions is not very helpful. As put by George Box (or by someone else before him), “all models are wrong, but some models are useful” and we (as statisticians) can devise tools to assess how wrong and how useful. Encouraging a total mistrust of anything scientific or academic is not helping in solving issues, but most surely pushes people in the arms of charlatans with ready answers.

via Andrew Gelman