Geography
Ecological Tipping Points
Ecological tipping points refer to critical thresholds in ecosystems where a small change can lead to a significant and often irreversible shift in the system. These points can result in abrupt and potentially detrimental changes to the environment, such as the collapse of a species population or the degradation of a habitat. Understanding and managing ecological tipping points is crucial for maintaining the stability and resilience of ecosystems.
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8 Key excerpts on "Ecological Tipping Points"
eBook - ePubEcosystem Crises Interactions
Human Health and the Changing Environment
- Merrill Singer(Author)
- 2021(Publication Date)
- Wiley(Publisher)
In 1985, Yadfon (which means Raindrop), a small development organization, began working with Leam Markham and Thung Dase villagers to rebuild and protect their mangrove forests. Villagers created a 235‐acre community‐managed forest and sea‐grass conservation zone. Mangrove seedlings were planted in degraded areas of the forest, while sea grass, which provides vital nursery areas and feeding grounds for many species of fish and shellfish, was replanted in the lagoon. Within several years, the environment tipped. Community‐managed mangrove forests began regenerating and the coastal fishery revived. This helped spark a regeneration of the village’s society and economy.Martens (2005 , p. 75) describes a parallel local case based on the work of Angel Alcala, a marine scientist from the Silliman University Marine Laboratory in the Philippines:Apo Island in the Philippines provides an example of environmental tipping points in action. The introduction of destructive fishing methods was a “negative tip” that set the regional fishery on a forty‐year downward spiral to virtual collapse. Apo Island escaped the downward spiral with a “positive tip”—the creation of a small marine sanctuary ‐which set in motion a cascade of ecological and social changes that restored declining fish stocks and returned the island’s marine ecosystem to health.The EcoTipping Points Project views such examples of working with environmental tipping points to recover desirable system states as a turn from vicious to virtuous cycles. Lenton et al. (2008 ) refer to them as “Gaia geoengineering,” after the ancient Greek god that personified Earth. While very beneficial at the local scale, however, small projects like those undertaken by Yadfon, the Silliman University Marine Laboratory, and numerous other NGOs and institutions in Thailand, the Philippines, and worldwide are “a stark reflection of our collective inability thus far to act to tackle the [ultimate] causes of climate change” and other anthropogenic ecocrises (Lenton et al. 2008 ). What is needed, in fact, Lenton et al. (2008
eBook - PDFThe Climate Casino
Risk, Uncertainty, and Economics for a Warming World
- William D. Nordhaus(Author)
- 2013(Publication Date)
- Yale University Press(Publisher)
If you think about the differences between modern houses and those of the eighteenth century, you can grasp how difficult it is to estimate the impact of future changes like sea-level rise on hu-man societies two or three centuries from now. (I return to an assess-ment of sea-level rise in Part III.) Other tipping points are even more difficult to assess. Scientists can estimate the scope and timing of melting of Arctic sea ice in the sum-mer. But the impact of this melting on commerce, wildlife, and ecosys-tems is very difficult to measure. What will it mean for Russia or Canada if their northern ports are open to shipping six months of the year? Equally perplexing issues involve the impacts of large-scale changes in the Amazon rain forest or the Sahara region. We might suppose that any change is unwelcome because people have adapted to the world as it is today. But that does not help us understand how serious it would be if the Sahara turned green or if the Amazon rain forest were trans-formed into savannah. The research on tipping points is in its infancy. Scientists have al-ready found new potential tipping elements since the first draft of this book was written. We can take steps to reduce the chances of crossing these boundaries, which are covered later in this book. But the main point to emphasize is that potentially dangerous discontinuities can oc- TIPPING POINTS IN THE CLIMATE CASINO 65 cur in complex systems. This is true of banks, frozen ponds, and global climate processes. Current research indicates that a number of sectors and earth systems may be threatened in the next century or so once the earth has warmed by 3°C or more. You might be wondering whether I am making a mountain out of a bump in the road. Climate change is part of earth’s history, from the warm periods of the dinosaurs to the cold periods when New England lay under a mountain of ice.
eBook - PDFA Brief History of the Earth's Climate
Everyone's Guide to the Science of Climate Change
- Steve Earle, Steven Earle(Authors)
- 2021(Publication Date)
- New Society Publishers(Publisher)
127 1 0 TIPPING POINTS I present multiple lines of evidence indicating that the Earth’s climate is nearing, but has not passed, a tipping point, beyond which it will be impossible to avoid climate change with far ranging undesirable consequences. —James Hansen, 20051 While the high-level climate talks pursue their stately progress towards some ill-defined destination, down in the trenches there is an undercurrent of suppressed panic in the conversations. The tipping points seem to be racing towards us a lot faster than people thought. —Gwynne Dyer, 20082 I n a lecture given in 2017, future-thinker Tony Seba showed a photograph of a New York street taken in 1900.3 The street is full of horses and horse-drawn carriages, with just a single motor car visible. He then showed a photo taken at the same location only 13 years later. The street is full of motor cars, with just a single horse visible. Some- time between 1900 and 1913, New York City crossed a tipping point in its transportation system. To put it into a climate-change context, advertising was the likely forcing mechanism, while convenience, speed, ostentation, social status, and envy provided strong positive feedbacks. The result was cleaner streets of course, and, 107 years later, a serious climate crisis. Approaching a climate tipping point is a bit like walking toward the edge of a cliff in the dense fog. You may know it’s out there, but 128 A BrieF History oF the Earth’s Climate you don’t know how close you are, and by the time you’ve crossed it, it is probably too late. To be more specific, a climate tipping point oc- curs when a region (or the Earth as a whole) crosses an irreversible threshold in its ecological or physical state, one that can lead to larger changes. The term “irreversible” is important here because it means that it isn’t possible for us, or any natural process, to undo the change, and that it probably won’t change back naturally, at least not on a human time scale.
eBook - PDFNatural Resources and Social Conflict
Towards Critical Environmental Security
- M. Schnurr, L. Swatuk, M. Schnurr, L. Swatuk(Authors)
- 2012(Publication Date)
- Palgrave Macmillan(Publisher)
It is also true that tipping points are absent from the first four IPCC assessment reports. Yet, since 2005, the concept of climate change tipping points emerged, and has been used primarily to argue that the prevailing discourse-images of climate change are encouraging a false sense of security. 64 Second, the partial reconfigura- tion of the epistemological hierarchy through this discourse-image of an earth system laden with tipping points owes something significant to the political and media strategies of the Blair government, which used this science to underpin (if not authorize) their efforts to move the discussion of climate change to sites not dominated by environmental concerns, namely the G8 summits and UN Security Council. Situating the science All of this suggests that, by the 1960s, two distinct ‘environmental sciences’ had emerged: one biology-centered, focused on problems in ecology and population studies, and funded in part by agencies and managers concerned about human threats to the environment; the other geophysics-centered, focused on the physical environment, and responsive to the operational needs of the military services that supported it. 65 One of the more remarkable findings in recent histories of the geophysical sciences is the extent to which our knowledge of the earth system reflected not only the Cold War context but also the specific operational and foreign policy demands of military actors. In fact, the very term ‘environmental sciences’ appears to predate the emergence of 1960s civilian-scientist research and 1970s regulatory institutions to originate instead from specific projects in the US military. 66 In Ronald Doel’s account, the result is two rather distinct strands of environmental science, and a pervasive military influence on geophysical/earth science research that remained less public – ‘often “born classified”’ – and effec- tively separated from the biological and activist traditions of research.
eBook - PDF- Christian L. E. Franzke, Terence J. O'Kane(Authors)
- 2017(Publication Date)
- Cambridge University Press(Publisher)
2 Tipping Points in the Climate System Peter Ditlevsen Abstract In climatic time series abrupt changes are observed. We hypothesize that these abrupt changes are due to nonlinear responses inherent in the climate system, specifically, so-called tipping points. This behaviour results from non-linear climate response to either external forcing, inter- nal stochastic fluctuations or a combination of both. At some point the forcing will cause the climate to jump from one stable state to another. This scenario is termed a tipping point. The concept of a tipping point is quite broad, but here we shall refrain from any general definitions and consider the following more restricted framework: We consider the climate or some components of the climate as a dynamical system depending on a set of parameters. Factors, not included in the system interacting with components of the sys- tem, can then be considered external forcing or stochastic fluctuations. Two common, and often competing, hypotheses are: The climate system’s steady state loses its stability and disappears as an external system (control-)parameter slowly changes, so-called b-tipping, b for bifurcation-induced; or fluctuations spontaneously push the climate system from one stable state to another, so-called n-tipping, n for noise-induced. The cause of the tipping can be very different in the two cases, and especially the possi- bility of predicting a tipping will be different. In the case that the underlying dynamics or the control-parameter are not completely known, there could still be early warning signals in the statistics of the observed fluctuations prior to a tipping point. 2.1 The Pleistocene Climate Record The Pleistocene climate is documented in a variety of geological records, most prominently in ocean sediment cores and ice cores. These all show that climate has changed abruptly through time both as response to the orbital changes and as a part of internal variability.
eBook - PDF- Marten Scheffer(Author)
- 2020(Publication Date)
- Princeton University Press(Publisher)
The birth of the Sahel–Sahara desert was most likely a critical transition related to such a feedback, and the Amazon basin may have a tipping point leading to a drier alternative stable state in which much of the forest is replaced by savanna. Terrestrial Ecosystems ■ 239 CHAPTER 12 Humans T he dynamics of human history are as jerky as the dynamics of ecosystems and the climate. Quiet periods occur but are inevitably interrupted by jumps varying from paradigm shifts to revolutions, wars, and state collapses. Although external disturbances such as abrupt climate change have been implicated in more than one example of so-cietal collapse, 1,2 many other dramatic societal changes seem to come without large external impacts. In this chapter, I will suggest that, just as in natural systems, gradual changes occasionally undermine re-silience, bringing a social system to a tipping point resulting in a self-propagating critical transition. Such transitions may be unwanted at times. However, as you will see, individuals as well as groups, compa-nies, and societies also have a tendency to get “locked” into a particular attitude or behavior, making them less responsive to changes. “Good” critical transitions may be needed to escape from such situations and other unwanted stable states, such as poverty traps and social disorder. Before highlighting similarities in dynamics, it is good to note some fundamental di ff erences in the mechanisms that govern dynam-ics social systems as opposed to “natural” systems. Learning, spread of information, and innovation play an overwhelmingly important role in societies. An important implication is that social systems never really shift back to a state that they have been in before, as ecosystems or the climate system sometimes do. Progressive change does occur in ecosystems through evolution and in the Earth system through conti-
eBook - PDF- Noel Castree, David Demeritt, Diana Liverman, Bruce Rhoads, Noel Castree, David Demeritt, Diana Liverman, Bruce Rhoads(Authors)
- 2009(Publication Date)
- Wiley-Blackwell(Publisher)
190 MATTHEW D. TURNER These disjunctures are surprising given the emphasis within policy and scientific circles, illustrated by terms such as sustainability and degradation, on understanding the longer-term persistence of an ecosystem’s productive potential. They are not surprising however when we consider temporal framing issues. Changes that are short with respect to human lifetimes and planning horizons are less likely to be ignored by researchers. Changes that are seen as long are more easily ignored. This is due to conceptual, policy and methodological issues. It is more difficult to study processes that transcend human lifetimes. These changes are less tractable and actionable by policymakers. Returning back to the deforestation example, the time needed for forest structures to be reestablished is longer than those for the reestab-lishment of herbaceous cover on a burned prairie. But is this the appropriate crite-ria? Are we not interested in post-deforestation ecological changes for their own sake not simply with an eye towards the reforested landscape? Adopting the defor-ested landscape as the endpoint implicitly treats subsequent ecological change as long-term and therefore emphasises structural recovery or return to ‘climax’ as the post-disturbance change of concern. Endpoints of change are necessarily established in all research. The choice of endpoints reflects not only how social-environment interaction is conceptualised and framed both spatially and temporally (as described above) but also the environmen-tal change’s policy relevance, economic importance, and feasibility of study. Political ecologists are more likely to incorporate the effects of resource extraction on eco-logical relations that have a direct influence on economy and politics. This results from their interest in the recursive relations between political economy and ecology over time.
- Olav Slaymaker, Thomas Spencer, Christine Embleton-Hamann(Authors)
- 2012(Publication Date)
- Cambridge University Press(Publisher)
The notion of temporal transition is intended to cover ways in which environmental changes are uniquely expressed. Although processes and landforms are driven by contemporary heat and moisture conditions, available relief and lithologies, they are not directly responding to them. They involve mechanisms or patterns of adjustment that are not readily obvious in climate change or tectonics. When geomorphic processes are modifying past land-scapes, the adjustments do not travel directly from one equilibrium to another. There are combinations of interven-ing constraints, self-adjusting mechanisms or ‘ epicycles ’ peculiar to the earth surface processes affected. In Canada, Church et al . ( 1999 ) have suggested that, at all scales above the order of 1 km², the landscape is still adjusting to the perturbation of continental glaciation. The fact that geomorphic systems have variable relaxation times following disturbance (i.e. time taken to return to the same conditions as those which prevailed prior to disturbance) has been well understood, but few careful quantitative studies have been available until recently. The response of the cryosphere to global environmental change, which demonstrates high sensitivity to temperature change through the threshold 0 ºC, is a more obvious exam-ple than the response of such an extensive and resistant landscape as the whole of Canada. There are radical differences in the role of geomorphol-ogy in global environmental change whether one takes the characteristic form approach or the transitional landscapes approach. At one level, it is a question of different punc-tuated equilibrium models of the landscape, where one is dominated by quiescence and the other by change. But it is not necessary to choose between the two approaches. There are elements of the landscape that have remained unchanged for long periods of time and others that are highly sensitive. The challenge and the opportunity of global environmental O. Slaymaker et al . 26
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