Category Archives: Visualization

Fishing through marine foodwebs

Tim Essington, Anne Beaudreau and John Wiedenmann have a interesting new paper in PNAS Fishing through marine food webs.

The paper elaborates on Pauly and others influential 1998 paper Fishing Down Marine Food Webs that showed that the mean trophic level of global fisheries statistics declined from 1950 to 1994 (from an average of 3.3 to 3.1).

Essington et al analyzed regional fisheries data from 1950 to 2001. They also found a decline in trophic level in 30 of 48 large marine ecosystems, and that the average decline was .42 trophic levels (almost twice as large as the decline found by Pauly et al). However, they did more than replicate Pauly et al’s work at a regional level, they also tested two alternative models of fishing down foodwebs – sequential collapse (the removal of top levels) vs. sequential addition (adding lower level fisheries). They evaluated these models by examining the temporal dynamics of upper-trophic-level fishery catches when fishing down the food web was occurring:

Under the sequential collapse replacement mode, a decline in the mean trophic level should be accompanied by reduced catches of high-trophic-level species as these species become economically extinct. Under the sequential addition mode, however, we expect catches of upper-trophic-level species to be maintained or even increase.

In the 30 large marine ecosystems that exhibited a decline in trophic level , they found 15 that matched the sequential addition model, 6 that showed no pattern, and 9 that showed sequential collapse. They differences between the two models are illustrated in Figure 1 from the paper, shown below.

Fishing down food websFig. 1. Illustrative examples of the sequential collapse replacement (A) and sequential addition (B) mode of fishing down the food web. Total yearly catch for each 0.1 trophic-level increment is indicated by the color bar on the right (104 kg yr 1). The mean trophic level (white line) was smoothed by using a locally weighted regression smoother. (A) The Scotian Shelf ecosystem exhibited a sharp decline in mean trophic level from 1990 to 2001 owing to the collapse of the cod fishery followed by a decline in the herring fishery and then the growth of the northern prawn fishery. (B) The mean trophic level of the Patagonian Shelf declined from 1980 to 2001, during which time catches for upper-trophic-level species (Argentinean hake) grew substantially while new fisheries for shortfin squid developed.

Essington and his coauthors point out that fisheries science, at least in the published literature, has assumed that fishing down food webs follows the sequential collapse model, and this model has different policy implications to the sequential addition model.

Perhaps the most important policy consideration of the sequential addition mode is that, in most ecosystems of the world, several trophic levels are now exploited simultaneously. These diverse fisheries impose conflicting demands on marine ecosystems that are not generally well represented in single-species management plans that do not consider the effects of these alternative fisheries on each other. As the structure of fisheries and the management environment evolve, the scientific community faces a new challenge of conducting broad-scale ecological research to support the development of more holistic, ecologically based approaches to fisheries management.

Another description of the research is provided in a U Washington press release.

Anthropogenic Modification of Vapours Flows and Tipping Points in the Earth System

Compare the map of soil moisture – atmosphere couplings against Gordon et al’s 2005 map of changes in vapour flows in the Human modification of global water vapor flows from the land surface.

PNAS Vapour Flows

Figure shows spatial distribution of net changes in vapor flows between potential vegetation and actual deforested and irrigated vegetation in mm/yr. The aggregated global change as compared with the potential vegetation is small (400 km3/yr), but the map illustrates the large spatial redistribution of water vapor flows from the land surface at the global scale.

Note that the location of increases in vapor flows in irrigation matches up with several of the hotspots identified in the map of soil moisture – atmosphere couplings – central Great Plains of North America, and India. Change occurs also in less intense hot spots appear in South America and China. Consquently, the combination of these two papers predicts that irrigation should have altered the local climate in these regions more than in other regions.

Leverage Points in the Earth System: Soil Moisture

The 2004 Science paper – Regions of Strong Coupling Between Soil Moisture and Precipitation – by Koster et al. used a dozen independent climate models to estimate ‘hot spots’ on Earth’s surface where precipitation is affected by soil moisture anomalies during Northern Hemisphere summer. They propose that these hot spots are, in a sense, land-surface analogs to the ocean’s “El Niño hot spot” in the eastern tropical Pacific.

Soil moisture is a slowly vary aspect of the Earth system (relative to weather). Soil moisture can persist for months. Soil moisture, influences evaporation and other surface energy fluxes can influence weather.

Soil moisture atmospheric coupling

Figure: Hot spots of soil moisture – local precipitation coupling appear in the central Great Plains of North America, the Sahel, equatorial Africa, and India. Less intense hot spots appear in South America, central Asia, and China.

The hot spots are located in regions that in areas that are at intermediate moisture levels. The authors argue that this is because in wet climates, soil water is plentiful and evaporation is controlled not by soil moisture but by net radiative energy. In dry climates evaporation rates are sensitive to soil moisture but they are small. Consquently the biggest impact of soil moisture on evaporation is in the transition areas between dry and wet climates.

What this analysis suggests is that these hotspots are areas in which changes in land use – especially those that alter soil moisture – such as irrigation or land clearing, will have a larger impact of regional climate.

Anoxic zones – mapping ecosystem tradeoffs (a start)

Current industrial agricultural practices, particularly the overuse of fertilizer and its sloppy management, frequently create a tradeoff between agricultural production and coastal eutrophication. That is increases in agricultural yields have produced low oxygen zones around the world. The UNEP Global Environmental Outlook 2003 maps the location of coastal anoxic zones world wide (somewhat confusingly the worst cases – the persistent ones are coloured yellow, next worst red and orange, and least worst blue).
Global distribution of oxygen-depleted coastal zones.

Global distribution of oxygen-depleted coastal zones. The 146 zones shown are associated with either majorpopulation concentrations or with watersheds that deliver large quantities of nutrients to coastal waters.


  • Annual – yearly events related to summer or autumnal stratification
  • Episodic – events occurring at irregularintervals greater than one year
  • Periodic – events occurring at regular intervals shorter than one year
  • Persistent –all-year-round hypoxia

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Bruce Mau @ McGill

Bruce Mau, a Canadian designer, recently gave the McGill School of the Environment‘s annual Environment Public Lecture at McGill University, on the ‘Future of Environmental Design,’ based upon the Massive Change exhibit developed for the Vancouver Art Gallery. The show was at the Art Gallery on Ontario in 2005, and will be at the Museum of Contemporary Art Chicago, in the fall of 2006.

The Massive Change project takes an optimistic, design oriented look at global social and environmental problems and suggests there are many existing resources and abilities that can be mobilized to improve the global human well-being, in areas such as transportation, cities, and manufacturing. My favourite part of the Massive Change exhibit was the visualization room – which filled the walls and floor of a room:

Visual Room VAG

The room is set up like a three-dimensional electromagnetic spectrum. The images made from low frequency waves (radio waves) are near the entrance, images made with visible light (red, orange, yellow…) are in the middle of the room, and images made using high frequency waves (gamma waves) are near the exit of the room.

Massive Change is oriented towards market based technological solutions to environmental problems and therefore in the language of the Millennium Ecosystem Assessment, it fits withthe TechnoGarden scenario, and indeed addresses many of the same issues, such as bus-rapid transit systems.

The exhbit/book/radio show/website were developed by Bruce Mau and a group of design students.

After hearing from Bruce Mau about the what the students did in these project I was inspired to try and build on our project courses in the McGill School of the Environment.
I think it would be great if we could run a similar type of workshop course here at McGill. That is a course that would encourage a team of students (somewhere between 7-25) to imagine what a sustainable McGill or Montreal could look like, and how we could get there over the next (5 – 25 years) and make there visions/proposal/syntheses into a series of public products such as an exhibit (ideally on the streets of Montreal), lecture series, a book, and website. I think they could build upon lots of work in synthesis and communication done by Massive Change, the Millennium Ecosystem Assessment, WorldChanging, and many others, to develop practical proposals for McGill and Montreal.

It is also interesting to think about what type of resilience oriented course with a larger international vision could be developed as a Resilience Alliance project. In either case, there are many details of time, money, and credit to work. But I think, there is a lot of potential for learning and innovation in real world, positive, synthetic courses.

Some other articles on Bruce Mau and Massive Change:
From architecture/design magazine MetropolisMag.comAt the Parsons Table with Bruce Mau, and from the business magazine Fast Company, Making a Map to a New World.

Mapping ecological footprint

The Ecological Footprint Network has some interesting maps and animations of “Footprint Intensity” between 1961 and 2001. The maps also show how the human Footprint has increased 2.5 X between 1961-2001.
Ecological footprint intensity is the footprint per 1/2 degree grid cell. These maps are made by combining population distribution maps and national level ecological footprint data.

The maps were created by Chad Monfreda at SAGE University of Wisconsin – Madison.

I previously posted on SAGE maps of disease burden and mapping humanity’s footprint.

Also, Marc Imoff et al (Nature 2004) have another map of human ecological appropriation.

Mapping Possibility of Alternative States in African savannas

At the end of last year M. Sankaran et al had a paper Determinants of woody cover in African savannas (Nature 2005 438(8) 846-849) that maps the possibility of savannas that can exist in alternative states based on rainfall.  This is the first map I have seen that maps the possibility of alternative states at a large  scale.

Map of alt savanna states in africa

Figure: The distributions of MAP-determined (‘stable’) and disturbance determined (‘unstable’) savannas in Africa. Grey areas represent the existing distribution of savannas in Africa. Vertically hatched areas show the unstable savannas (>784mm MAP); cross-hatched areas show the transition between stable and unstable savannas (516–784mm MAP); grey areas that are not hatched show the stable savannas (<516mm MAP).

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Has the world become a better place?

global development

Gapminder, which I mentioned in March 2005, has a nice visualization that shows changes in family size and child mortality between 1960 and 2003 to address the question – has the world become a better place?

The visualization shows huge changes in child mortality and family size, with some countries in Africa lagging behind. This convergence in well-being is much stronger – as mentioned in this earlier post.
The site also has a new visualization of data from UNDP’s 2005 Human Development report.