Archive for the 'Regime Shifts' Category

Algal Bloom along the Coast of China

Published by Garry Peterson on July 9, 2008 in Regime Shifts and Visualization. 0 Comments

There has been a lot of news coverage of the large coastal algal bloom at China’s Olympic sailing site in Qingdao. The Chinese government claims the bloom is now under control.

NASA’s Earth Observatory has published some remote sensed images of the bloom from MODIS:
MODIS comparison of algal bloom

On June 28, 2008, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured these images of Qingdao and the bay of Jiaozhou Wan. The top image is a natural-color image similar to what a digital camera would photograph. The bottom image is a false-color image made from a combination of light visible to human eyes and infrared light our eyes cannot see. In this image, vegetation appears vibrant green, including the strips of algae floating in the bay and in the nearby coastal waters.

These images show the bay at the beginning of a local cleanup effort. (Daily images of the area are available from the MODIS Rapid Response Team.)

The long history of human-environment interactions in China

Published by Elena Bennett on July 9, 2008 in Regime Shifts. 0 Comments

In a recent paper, JA Dearing and colleagues (J. Paleolimnology 40: 3-31) use paleolimnological techniques to explore the long-term history of the region around Erhai Lake in Yunnan Province. Lake sediment cores (which can explain catchment vegetation, flooding, soil erosion, sediment sources and metal workings) are complemented by independent regional climate time-series from speleothems, archaeological records of human habitation, and a detailed documented environmental history. The authors integrate these data to “provide a Holocene scale record of environmental change and human–environment interactions.”

They use these data to ask:

  • “How sensitive are the studied environmental system processes to climate and human drivers of change?”
  • “Can we observe long-term trajectories of socio-environmental interactions, or periods of social collapse and recovery?”

The authors identify a number of points at which there were major changes in the human interaction with the landscape, including ~9000 cal year BP, when sediment records show a ‘human-affected environment’, ~4800 cal year BP, when major deforestation for grazing led to the extirpation of forest species and some functional units, and ~2000 cal year BP at the introduction of paddy field irrigated farming, and ~1600 cal year BP at which point surface erosion and gullying were caused by increased exploitation of mountain slopes. They go on to suggest that these records indicate several major ‘periods’ in human-environment interactions in this area:

The earliest of these cases probably represents the dispersion of the population away from the established sedentary agricultural units on alluvial fans to the more inhospitable margins of the lake and the valleys. This perhaps signifies the end of the ‘nature dominated’ phase (Messerli et al.) where society could cause significant modification of the landscape but was still vulnerable to the main risks of drought and flood (though the evidence for climate determinism is weak). In contrast, the introduction of irrigation is associated with a trend of weakening monsoon intensity, increasing numbers of centennial scale dry phases, and population growth. It represents an agrarian society in transition, using technological innovation to raise carrying capacities without increasing greatly the vulnerability to drought or flood. The third period is linked to natural population growth, inward migration and metal extraction brought about by the rise of Nanzhao/Dali as a major center”

The authors then ask at what stage of the adaptive cycle the modern Erhai socio-ecological system exists:

At Erhai, the slow processes of weathering and soil accumulation, in association with vegetation cover held fairly constant by a benign early-mid Holocene climate, were interrupted by fast processes of anthropogenic modification of vegetation. For many centuries, this concatenation of ‘slow–long’ and ‘fast–short’ processes led to a resilient land use-soil system (cf. Gunderson and Holling). But increasing perturbations led to system failure, and we can observe that the late Ming environmental crisis represents the end of the last release phase. Thus, the modern landscape may be approaching a conservation phase (K) characterised by minimum resilience.

Dearing and colleagues explore the meanings of this research for current sustainability and conclude that the main threat to the region is high magnitude-low frequency flooding of the agricultural plain and low terraces, which is exacerbated by:

  1. continued use of high altitude and steep slopes for grazing and cultivation that generate high runoff from unprotected slopes and maintain active gully systems, particularly in the northern basins;
  2. reduction or poor maintenance of paddy field systems, engineered flood defences, river channels and terraces; [and]
  3. increased intensities of the summer monsoon.

This fascinating paper is an excellent example of how historical data sources can be integrated to provide a new perspective on social and ecological change over long periods of time.

Intensive agriculture’s ecological surprises

Published by Garry Peterson on July 4, 2008 in Ecosystem services and Regime Shifts. 2 Comments

regime shift cartoon from TREE paperRhitu Chatterjee has written a news article Intensive agriculture’s ecological surprises in Environ. Sci. Technol. (July 2, 2008) about a paper Agricultural modifications of hydrological flows create ecological surprises (doi:10.1016/j.tree.2007.11.011) that Line Gordon, Elena Bennett and I published in TREE earlier this year.  From the article:

Previous reports have outlined ways that agriculture alters ecosystems by changing hydrology. The new study, led by Line Gordon of the Stockholm Resilience Centre, classifies these changes, or “regime shifts”, from one ecological state to another into three categories: through agriculture’s interaction with aquatic systems, as in the case of nutrient runoff; in the interactions of plants and soil, as in Australia’s salinity issues; or by influencing atmospheric processes such as evaporation and loss of water by plants (transpiration), as in the rapid drying of the Sahel in sub-Saharan Africa.

The authors “make it clear that agricultural practices result in these regime changes by altering water quality and available quantity,” says Deborah Bossio, a water expert at Sri Lanka’s International Water Management Institute.

“The increasing demand for food, feed, and fuel is placing enormous pressure on the world’s arable lands,” says ecologist Simon Donner of the University of British Columbia (Canada). Awareness of agriculture-related environmental problems has been growing in the past few years, says Bossio. But some of that awareness has been lost in the “current frenzy of global food crisis shifting the balance back toward increasing yield.”

Be it the desertification of the Sahel, the dead zone in the Gulf of Mexico, or the increasing salinity in Australia, countries all over the world are already trying to solve some of these problems. But the fixes are not quick, and the results of their efforts are often hard to predict.

Given the difficult-to-repair, or even irreparable, nature of the problems, agricultural systems must be made resilient to change, the authors argue. The new study adds to “the increasing chorus of voices” that emphasizes the need to avoid irreversible ecological damage, says Donner.

However, the science of understanding ecological regime shifts is still young, which makes it difficult to predict when the changes will manifest. “The tipping points aren’t very well understood at all,” says Bossio. Researchers first need to understand the various biophysical factors involved and how those factors interact with one another, the authors say.

For now, ecologists, agronomists, and regulators can acknowledge the problem and encourage certain practices to minimize the likelihood of some of these water-related changes. People should begin by viewing agriculture not simply as a source of food but also as a source of ecosystem services like water and biodiversity, says coauthor Garry Peterson of McGill University (Canada). For example, Australian farmers are adopting mosaic farming, which involves combining annual crops, pastures, and perennial trees into the same landscape. This restores biodiversity and hydrology and prevents the rise of salinity.

“If we don’t heed the management lessons from the past, many of which are listed in the paper, we are bound to face many more ecological surprises in the coming decades,” says Donner.

Regime shifts in the Gulf of Mexico

Published by Garry Peterson on June 25, 2008 in Regime Shifts. 1 Comment

Regime shifts in the Gulf of MexicoEugene Turner, Nancy Rabalais, and Dubravko Justic’s recent article Gulf of Mexico Hypoxia: Alternate States and a Legacy (Env. Sci. Tech., 2008 42(7) 2323–2327) suggests that benthic carbon in the coastal benthic may be a critical slow variable regulating coastal hypoxia. As organic matter accumulates in sediments it demands increasing amounts of oxygen, making the area more vulnerable to nutrient driven hypoxia.

The Gulf of Mexico is one of the most studied coastal hypoxic zones in the world, but it is not the only one. The number of these zones has greatly increased, primarily due to agricultural expansion and intensification (one of the many ways that agriculture has been driving ecological regime shifts). The authors compare changes in coastal hypoxia in the Gulf of Mexico to that found in the Baltic Sea, which has also been suggested to have undergone a regime shift. The authors conclude:

… there has been a system-wide response to the combination of organic buildup in the sediments and higher nitrogen loading, which has increased the area of hypoxia generated for a given nitrogen load and has increased the opportunity for hypoxia to develop. The results discussed above demonstrate that the average [nitrogen] loading of the 1980s would result in a hypoxic zone that is twice as large in the past decade.

…Hypoxia has well-documented catastrophic consequences to the benthos, including animals with multiyear life spans, and creates large areas without commercial quantities of shrimp and fish. The changes in the Mississippi River-influenced continental shelf over the last 30–40 years should be considered to a shift to an alternate state in the sense that (A) the threshold for hypoxia development has been exceeded on a continuing basis and the size of the hypoxic zone has increased and may be approaching its maximum size, given physical constraints on shelf geometry (e.g., width, depth, and length); and (B) the return to a previous system state is more difficult the longer that the current level of nutrient loading is stable or increasing.

… respiratory demand in the sediments remains a legacy influencing water quality of the eutrophied continental shelf in the northern Gulf of Mexico. …The goal of reducing the size of the hypoxic zone to 5000 km2 thus becomes more difficult to achieve for every year without a significant reduction in nutrient loading. Each year without reducing the nutrient loading rates means that it will take longer to realize the Action Plan goal, because the legacy of accumulated organic matter and its respiratory demand increases with time.

The Mississippi dead zone will grow due to this year’s floods

Published by Garry Peterson on June 17, 2008 in Regime Shifts. 1 Comment

Low oxygen anoxic zones due to excess nutrient runoff from agriculture and are increasingly common worldwide. On Maribo Simon Donner writes about how the ongoing floods in the upper Mississippi are likely to produce the largest ever ‘dead zone’ in the Gulf of Mexico. Simon writes:

Nitrogen applied to crops like corn in the Midwest is the major driver of the now famous Dead Zone, as I’ve described in a number of previous posts and this Google News commentary. The blame for the high nitrogen levels in the Mississippi and this year’s record Dead Zone forecast is being placed on the production of more corn for ethanol. A more complete explanation would be that the surge in corn production, and, hence, fertilizer use, the past few years has made nitrogen pollution more sensitive to the climate than ever.

Nitrogen and hydrology are tightly linked in the Mississippi River Basin, and other agriculturally intensive river basins, thanks to nature and to humans. Several nitrogen ’species’ like nitrate are highly soluble. What has exacerbates things in the Mississippi is activities like wetlands, installing artificial drainage under fields and channelizing rivers that reduce chances for nitrogen to be consumed before moving downstream. The result is the amount of nitrogen that the Mississippi sends to the Gulf can actually be predicted from the rainfall in the Corn Belt.

In coverage of our recent paper on corn and the Dead Zone, the prediction that the US Energy Policy would increase average nitrogen loading by 10-34% drew most of the attention. What might be missed is that the nitrogen loading could be much higher if the conditions are wetter.

The reason this matters is the the continental shelf of the Gulf of Mexico has a memory. The usual tale is that the Dead Zone grows each spring and summer when the big flood of Mississippi nitrogen arrives weather and water conditions are ripe for algae growth (it breaks up in the fall when the waters cool and mix, reintroducing oxygen to the bottom waters). However, nitrogen from previous years that is deposited in the sediments can also be recycled and feed algae growth. In other words, the system remembers a big flood of nitrogen. For example, during the 1993 Mississippi floods, the Dead Zone grew to a then-record 17,600 km2; the next year, it grew to an almost equal 16,600 km2, despite 31% less nitrate flowing down the Mississippi. That’s just one reason why it is critical to consider climate and climate variability in ecological management and policy.

This year, the Dead Zone is projected to reach over 25,000 km2 in size, 20% greater than the previous maximum. What will that mean for 2009? For 2010? The longer you wait, the harder problem like the Dead Zone are to solve.

A giant pool of money flows into global agriculture

Published by Garry Peterson on June 5, 2008 in Ecological Economics, Ecosystem services, Greenlash and Regime Shifts. 1 Comment

As part of its interesting Food Chain series, the New York Times writes Food Is Gold, So Billions Invested in Farming about how investment funds are pouring billions of dollars into agriculture. One investment bank has estimated that investments in agricultural commodities has increased over 3X, from $70 billion at the start of 2006 to $235 billion in April of 2008, with roughly half of this growth being due to appreciation and half to new investment (for more details see Financial Times on agricultural funds and why food prices are rising?). However, money is now moving from investments in commodity futures into actual agricultural infrastructure:

Huge investment funds have already poured hundreds of billions of dollars into booming financial markets for commodities like wheat, corn and soybeans. But a few big private investors are starting to make bolder and longer-term bets that the world’s need for food will greatly increase — by buying farmland, fertilizer, grain elevators and shipping equipment.

Part of the article is reminiscent of the TechnoGarden scenario of the MA, in which rich companies invest in the underdeveloped African agriculture infrastructure. The article states:

Emergent is raising $450 million to $750 million to invest in farmland in sub-Saharan Africa, where it plans to consolidate small plots into more productive holdings and introduce better equipment. Emergent also plans to provide clinics and schools for local labor.

One crop and a source of fuel for farming operations will be jatropha, an oil-seed plant useful for biofuels that is grown in sandy soil unsuitable for food production, Ms. Payne said.

“We are getting strong response from institutional investors — pensions, insurance companies, endowments, some sovereign wealth funds,” she said.

The fund chose Africa because “land values are very, very inexpensive, compared to other agriculture-based economies,” she said. “Its microclimates are enticing, allowing a range of different crops. There’s accessible labor. And there’s good logistics — wide open roads, good truck transport, sea transport.”

However, unlike the TechnoGarden scenario, this investment seems focussed on increasing yields of food and fuel, rather than producing multiple ecosystem services. Consequently, such investments attempts to increase yields by practicing intensive agriculture are likely to lead to negative impacts on other people and ecosystems using water, and potentially leading to local or regional ecological regime shifts (see our paper Gordon et al 2008).

Also, many of these investments are not aimed at increasing agricultural yield on the ground, but hedging against inflation risk, and providing market power for large funds to leverage investments in other financial instruments, such as options, derivatives and other more complicated packages. This coupling of financial markets, to the already coupled food, fuel, and climate systems means that the systemic consequences of these investments are likely to be unexpected and novel.

Brian Walker’s Research Areas for Resilience Science

Published by Garry Peterson on May 20, 2008 in Adaptation, Ecological Economics, Ideas, Reflections, Regime Shifts, Reorganization and Vulnerability. 1 Comment

Brian Walker, the former director of the Resilience Alliance reflected on the future of resilience science in his introductory talk at Resilience 2008. In his talk Probing the boundaries of resilience science and practice, he identified seven important research areas for resilience science:

  1. Test, criticize and revise the propositions about resilience made in Panarchy: Understanding Transformations in Human and Natural Systems and Ecology and Society special issue – Exploring Resilience In Social-Ecological Systems.
  2. Develop models of social-ecological systems that can produce the key aspects of the rich behaviour of the world. In particular these models should be able to produce:
    i) dynamics in which systems cross multiple thresholds,
    ii) produce “backloop” dynamics, and
    iii) incorporate models of adaptive governance that incorporate leadership, trust, ‘shadow’ networks, sleeper links, and poly-centric governance arrangements.
  3. Extend resilience theory from local or regional scales to the global to address questions such as:
    i) Do we need new propositions for global resilience issues?
    ii) Over what ranges of scale can we apply existing theory?, and
    iii) How important are scale-dependent processes?
  4. Resilience theory needs to better understand the consquences of multiple simultaneous shocks, because transformative change seems to be often triggered by two (or more) simultaneous shocks. For example an environmental shock and an economic (or political) shock occurring at the same time.
    Resilience theory needs to understand what coupled or sequential shocks are likely, and how could we go about assessing resilience to them. An example of this is the current food crisis that developed from the coupling of agriculture, energy, and climate issues.
  5. What are the differences between transformational change, adaptability and resilience? Transformability is the capacity to create a fundamentally new system when conditions make the existing system untenable. In much of the world the need is to transform, not to make the existing system regime more resilient. What are the design principles of transformations?
  6. How can we assess the costs and values of resilience? What is the difference between general (broad spectrum resilience to many things) vs. specified resilience (to a few specific things)? How can we conceptualize the danger in ‘optimizing’ for specified resilience? How much should we spend (or forego) to increase resilience?
  7. How can the value of different regimes be assessed? The desirablity of a regime usually depends upon the perspective it is viewed from, and different people have different perspectives. Coping with these perspectives is a challenge. But more fundamentally, this requires not just assessing the value of different ecosystem services, but also understanding the identity of a system, and its ability to maintain itself.
  8. Non-mathematical approaches to resilience. While mathematics is beautiful to some, it is difficult to communicate and in some situations is insufficient. We need to increase our ability to represent resilience in a variety of forms. This presents a challenge to the humanities and arts community. At Resilience 2008 we saw contributions towards this understanding, but there is much more to develop. Can science and the humanities work together to provide the impetus towards a richer, more resilient world?

Biofuel prodcution vs. Aquatic ecosystems

Published by Garry Peterson on March 12, 2008 in Ecosystem services, Greenlash and Regime Shifts. 2 Comments

Simon Donner writes about his new paper Corn-based ethanol production compromises goal of reducing nitrogen export by the Mississippi River (Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0708300105) on his weblog maribo:

A new paper by my colleague Chris Kucharik and I looks at the new US Energy Policy, will calls for growing more corn to produce ethanol, will affect the “Dead Zone” in the Gulf of Mexico. For a quick summary, see Reuters, the CBC or AFP.

The Mississippi dumps a massive amount of nitrogen, largely in the form of the soluble ion nitrate, into the Gulf each spring. It promotes the growth of a lot of algae, which eventually sinks to the bottom and decomposes. This consumes much of the oxygen in the bottom waters, making life tough for bottom-dwelling fish and creatures like shrimp. The Dead Zone has reached over 20,000 km2 in recent years.

The primary source of all that nitrogen is fertilizer applied to corn grown in the Midwest and Central US. Reducing the Dead Zone to less than 5000 km2 in size, as is suggested in US policy, will require up to a 55% decrease in nitrogen levels in the Mississippi.

The new US Energy Policy calls for 36 billion gallons of renewable fuels by the year 2022. Of that, 15 billion can be produced from corn starch. Our study found meeting those would cause a 10-34% increase in nitrogen loading to the Gulf of Mexico.

Meeting the hypoxia reduction goal was already a difficult challenge. If the US pursues this biofuels strategy, it will be impossible to shrink the Dead Zone without radically changing the US food production system. The one option would be to dramatically reduce the non-ethanol uses of corn. Since the majority of corn grain is used as animal feed, a trade-off between using corn to fuel animals and using corn to fuel cars could emerge.

Paul Krugman on Resilience Economics

Published by Garry Peterson on March 11, 2008 in Regime Shifts. 2 Comments

On Paul Krugman’s Blog he presents a graphical model of the current financial crisis in the US that implicitly discusses how the system lost resilience. He identifies leveraged investments as a slow variable which can lead to the creation of alternative regimes, the possibility for a shock to flip the system from one regime to another, and now possibly a new regime.

Krugman RS

The other day I realized how much the Fed’s attempts to resolve the financial mess resemble sterilized foreign exchange intervention. That set me thinking about other parallels — and I realized how much the stories now being told about “systemic margin calls” and all that resemble the stories we all tried to tell about the Asian financial crisis of 1997-98. Leverage, balance sheet effects, self-reinforcing financial collapse — the details are different, but there are some clear common themes.

…Think of the demand for “securities” — lumping together all the stuff that’s in trouble, from subprime to Alt-A to corporate bonds, as if it were all the same. Ordinarily we’d think of a downward sloping demand curve. At a given point in time, there’s a fixed supply of these securities that has to be held by someone [Normal Situation]

But in the current situation, a lot of securities are held by market players who have leveraged themselves up. When prices fall beyond a certain point, they get calls from Mr. Margin, and have to sell off some of their holdings to meet those calls. The result can be a stretch of the demand curve that’s sloped the “wrong way”: falling prices actually reduce demand.

In this case, there are two equilibria, H and L. (there’s one in the middle, but it’s unstable) And this introduces the possibility of self-fulfilling panic: if something spooks the market, you can get a “systemic margin call” that causes the whole financial market to go to L, and causes a big, unnecessary price decline. [Highly leveraged investment]

Implicitly, Fed policy seems to be based on the view that if only they can restore confidence — with extra liquidity to the banks, Fed fund rate cuts, whatever — they can get us out of L and back to H. That’s the LTCM model: Rubin and Greenspan met a crisis with a rate cut and a show of confidence, and the whole thing went away.

But at this point a series of rate cuts and other stuff just hasn’t done the trick — which suggests that maybe there isn’t a high-price equilibrium out there at all. Maybe the underlying losses in housing and elsewhere are sufficiently large that the situation really looks like this [current situation?]

And in that case, the Fed can’t rescue the financial markets. All it — and the feds in general — can do is to try to limit the effects of financial crisis on the rest of the economy.

Climate Change May Transform Fire Regime in Tundra

Published by Garry Peterson on March 6, 2008 in Regime Shifts. 0 Comments

arctic tundraPhilip Higuera and collaborators suggests that based on paleo-ecological analysis of past fire regimes, climate change could lead to abrupt shifts in tundra fire frequency as climate change vegetation shifts from herb to shrub dominated tundra.

In their article (Higuera PE, Brubaker LB, Anderson PM, Brown TA, Kennedy AT & Hu FS. 2008 Frequent fires in ancient shrub tundra: implications of paleorecords for Arctic environmental change. PLoS ONE DOI: 10.1371/journal.pone.0001744) the authors write:

… paleorecords from northcentral Alaska imply that ongoing shrub expansion and climate warming will result in greater burning within northern tundra ecosystems. The geographic extent of fire-regime changes could be quite large, as shrubs are expected to expand over the next century in both herb and low shrub tundra ecosystems, which comprise 67% of circumpolar Arctic tundra [10], [15] (Fig. 1). Over this same period, annual temperatures in the Arctic are projected to increase between 3–5°C over land, lengthening the growing season and likely decreasing effective moisture (in spite of increased summer precipitation) [8]. How long might it take for the current shrub expansion to trigger a significant change in fire frequencies? Within the chronological limitations of our records, past shrub expansion and fire-regime changes at each site occurred within a few centuries (Fig. 2). The duration of this shift is consistent with the estimated rate of shrub expansion within a large area of northern Alaska [0.4% yr−1 for ca 200,000 km2; 10]. Based on a simple logistic growth model and the assumption of a constant expansion rate, Tape et al. [10] hypothesize that the ongoing shrub expansion in this region started roughly 125 years ago and should reach 100% of the region in another 125 years. Thus, if fuels and low effective moisture are major limiting factors for tundra fires, we predict that fire frequencies will increase across modern tundra over the next several centuries.

…

Despite these uncertainties, Alaskan paleorecords provide clear precedence of shrub-dominated tundra sustaining higher fire frequencies than observed in present-day tundra. The future expansion of tundra shrubs [10], [16] coupled with decreased effective moisture [8] could thus enhance circumpolar Arctic burning and initiate feedbacks that are potentially important to the climate system. Feedbacks between increased tundra burning and climate are inherently complex [3]–[5], but studies of modern tundra fires suggest the possibility for both short- and long-term impacts from (1) increased summer soil temperatures and moisture levels from altered surface albedo and roughness [24], and (2) the release soil carbon through increased permafrost thaw depths and the consumption of the organic layer [24], [25]. Given the importance of land-atmosphere feedbacks in the Arctic [26]–[28], the precedence of a fire-prone tundra biome should motivate further research into the controls of tundra fire regimes and links between tundra burning and the climate system.

Climate driven changes in vegetation cover across the most northern land surfaces on the planet will likely result in more carbon-releasing fires, according to a study published this week in PLoS ONE. Philip Higuera, currently at Montana State University, and colleagues examined charcoal and pollen samples from Alaskan lakes, which provide a historical record of plant composition and fire frequency between 14000 and 10000 years ago. Back then, the tundra was dominated by extensive thickets of resin birch Betula glandulosa, and the warming climate is likely to see its widespread return to areas currently occupied by somewhat less flammable herbs. The mass of tangled, resin-laden twigs could turn the area into a tinderbox, with the double whammy that such fires encourage vigorous birch regrowth, making it prone to further blazes. The likely consequence is that another source of carbon dioxide will enter the scene, as vegetation and long-frozen soil go up in smoke.

via SCB’s Journal Watch Online

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