Sunday, 28 December 2014

Lesson, insight, and afterthought.

One Ocean, One Index – a 'Composite Essay' on Opportunities and Limits.

The ocean-health index is a challenging attempt, namely to describe a set of assets through a single index. Setting up the index and reviewing it teaches lessons on the human-ecological intersections of the human-ocean system, including the issue of appropriate mathematical methods "how to calculate its scores".

My first insight:

Setting up an ocean-health index [1] was an a lasting contribution to the management of the human-ocean system. An ocean-health index can be a tool for comparison of national and regional policies, benchmarking, and qualification of development options. That is much needed to manage global commons like the ocean.
Implications of the (simple) mathematics to calculate the score of ocean-health index have been analysed [2] and suggests that the mathematical method chosen for calculating the score is causing bias of the index. The method, “weighted arithmetic average”, makes the score insensitive to less appropriate balances between low-performance assets and better-performing assets. The feature “unconstrained mutual substitution between assets” that is implicit to the averaging method to obtain the score of the index limits its usefulness [2]: "policy assessment and advice based on an index with unconstrained substitution possibilities could result in (a) certifying a healthy human-ocean system for countries that in reality neglect important aspects of ocean health and (b) identifying development trajectories as sustainable although this is not the case."

My second insight:

Constrained mutual substitution of assets should improve the assessment of the various oceanic features that are relevant for societal wealth and human development. Evidently, the substitution of different assets is a societal endeavour. It requires knowledge, social choices and norms and particular the latter may evolve and vary among societies.
Substitution possibilities should be constrained by the boundaries to the elasticity of the ocean system. If we do not know this ‘elasticity’ then “strong sustainability concept” or even the “precautionary principle” should be applied. Substitution possibilities should provide for a margin for management decisions - not everything goes, not all is forbidden – to render the ocean-health index a practical tool with operational value.

My third insight:

For better or for worse, a common and robust ocean-health index is a welcomed management tool, and should be part of any mature ‘blue economy strategy’. Thus, it is important to strengthen the index in a manner that enables its sound use in practice. Thus, furthering the analysis is needed, be it of suitable asset substitution or how to describe the substitution process in mathematical terms, to properly evaluate benefits, risks and development options of the ocean-human system.
In the absence of such an index, the alternative would be to manage all assets one-by-one using the "strong sustainability concept" or even the "precautionary principle". Such a choice has the intrinsic risk of a political process to retain only those assets that the strongest lobby considers to be most relevant. Such a situation certainly will be detrimental for the overall balance among assets, to the comparison of national and regional policies, benchmarking, and qualification of development options.
Thus, one composite index has a strong appeal. However, attention should be given to the averaging procedure, which, if too complex or perceived as too complex, would hamper application. To recall, the attractiveness of estimating the ocean-health index by a weighted arithmetic average is the simplicity of the mathematical procedure.

An afterthought: 

Possibly a two tiers approach may provide a useful compromise for now. Tentatively, such a compromise could be: (i) apply the "strong sustainability concept" to divide the entire set of assets in two sub-sets; one sub-set for the assets that match the respective threshold and the other sub-set for the assets that fail the respective threshold. (ii) calculate the score of the ocean-health index for both sub-sets and the entire set, and (iii) present the score for the full set with the scores for the sub-indexes as lower and upper bounds.

[1], [2] for references see "One Ocean, One Index – a 'Composite Essay' on Opportunities and Limits" 

Excursions - one, two, three.

The ocean-health index is calculated as a “weighted arithmetic average”. That “weighting” does not look too much as problem. It makes the averaging a bit more complex as taking a simple “arithmetic average”. The “weighting” allows to account for some features that are a bit more important as other. The more important assets get “a bit more” weight and thus they determine the average a bit more as the less important assets. Setting the weights may give some room for tweaking the average, but can be understood easily and therefore “tweaking or cheating” can be made evident.
The mathematics of an "arithmetic average" look even more innocent and non-problematic; likely it is the most frequently used methods to calculate averages. An "arithmetic average" makes good sense, if the same feature is measured several times, and each measurement has a small random error. An "arithmetic average" also makes a good sense if no preferences shall be made among measurements. If preferences shall be made then weighting measurements is a transparent approach to set these preferences. Pushing these considerations further: facing the intrinsic complexity to balance different assets using the arithmetic average is like taking the approach "one asset one vote". And, on the other hand, attributing different weights to different assets can help to reflect social or political choices without excluding a "minority asset"; thus it is like an "affirmative action". Thus, considering the averaging method from a political angle the "weighted arithmetic average" looks much like as "applying first principles".
Nevertheless, these apparently simple averaging is not an innocent choice. It applies a specific “normative frame[s]” [2] embedded into the index and thus applied to the management of the assets. In a nutshell: The difficulty with arithmetic averaging is just that no preference is made. This “normative frame”, the implicit assumption behind arithmetic averaging, may effect the usefulness of the index as a management tool.
Using an “arithmetical average” to score a set of assets implies the assumption: assets can replace each other and the same score is calculated. Thus, “unconstrained substitution possibilities” exist among assets to obtain the same average score. In the term “unconstrained substitution possibilities” the notion “substitution” means that under-performance for one asset can be balanced by better-performance for another asset; “unconstrained” means that under-performance for one asset is not limited by a lower boundary; and “possibility” means that better-performance for any asset may balance under-performance of any asset. These assumptions are quite radical, indeed, and offer a wide range of management choices.
Using a “weighted arithmetic average” does not alter qualitatively the assumption of “unconstrained substitution possibilities”. Using a “weighted arithmetic average” modifies the “cost” of the substitution: performance for an asset with low weight has to improve much to balance a minor drop of performance of an asset with a high weight.

Excursion Two: A radical 'normative frame'?
Let's illustrate - by an example - “unconstrained substitution possibilities among various assets”: Assume first a shopping list of ten items for a tasty dinner; assume further getting these items in different quality and quantity, but so that, and this is the third assumption, the average “palatableness” of the dinner is the same. Evidently, a good starter may make good for an mediocre desert, or a good wine (or beer) compensates for…; but unconstrained substitution possibilities among the various parts of the dinner and same 'palatableness'? Common sense suggests that this may not work. However, consider a hypothetical "palatableness index" that is defined as the weighted arithmetic average of the quality and quantity of the items purchased for the dinner". In terms of that index, a dinner should have the same "average tastiness" as long as the score of the "palatableness index" is the same.
Evidently, “unconstrained substitution possibilities among various assets”, if it works, would be a framework for “a manager’s dream”. Such a framework would maximise the number of operational alternatives to amalgamate assets. In reality, "unconstrained substitution possibilities among various assets" is an exceptional case. It is rather "the real-world's manager's headache" that amalgamating assets is limited by their mutual substitution potential. The substitution potential may be limited for ecological, technical reasons or social preferences or economic viability to name but the most obvious. It is implicit for the application of ocean-health index to managerial or political choices that different assets can substitute each other, at least to some degree. It is implicit also, that assuming the full substitution of assets is problematic. Thus, how to describe these limitations by an appropriate mathematical method.

Excursion three: Mathematics for strong, weak or intermediate sustainability ?
The concepts of "strong sustainability" and "weak sustainability" can be used to compare different options to substitute assets. The "strong sustainability" concept constraints substitution options; all assets shall be kept above an asset-specific critical level. Under the "weak sustainability" concept, the substitution between assets is unconstrained.
In mathematical terms, the concept of “unconstrained substitution” is implicit to the ocean-health index calculated by a [weighted] arithmetic mean. Experienced managers of marine resources will be aware of limitations to substitution of assets, and thus will not accept any 'blind' averaging. However implementing that awareness in a competitive environment is fraught with difficulties, and therefore mathematical methods to describe “intermediate levels of substitution” may be appreciated as management tool.
The mathematical methods to describe "intermediate levels of substitution" are available [d]. Aggregation of scores for individual assets into a composite score under conditions of constraint or limited substitution can be described using ‘generalized averages' [e]. Arithmetic, geometric or harmonic averages are as special cases of the ‘generalized average'.

Obviously, intermediate levels of substitution of assets may be achieved for many real-world situations. Evidently, for many real-world situations it will be difficult to determine "what are boundaries to substitution?" Manifestly, any intermediate level of substitution of assets will depend on the specific ecological-human intersections of the respective human-ocean system. Nevertheless, whatever appears “obvious”, “evident” or “manifest”, it will be hard and tedious work to narrow the range of substitution possibilities. Therefore one may argue that "strong sustainability" should be applied across the board to guide management choices, and be it only for the sake of simplicity.

[2], [d], [e],  for references see "One Ocean, One Index – a 'Composite Essay' on Opportunities and Limits" 

The Ocean Health Index - mathematics visited.

One Ocean, One Index – a 'Composite Essay' on Opportunities and Limits.

The scrutiny: Composite averaging and intermediate level of substitution
Rickles and co-workers [2] illustrate how limited substitution possibilities can be implemented for the ocean-health index using appropriate mathematics, i.e. specific functional forms ("functions of functions") [f]. The mathematical methods for calculating the index can get increasingly composite. They may combine nested approaches, generalized means, variable setting of substitution, constraints on the overall score for the less-performing assets, "hard" lower boundaries, etc.
Evidently, such kind of "composite averaging procedure" lacks the simplicity of the arithmetic average. The "composite averaging procedure" is an elaborate model of the substitution possibilities, which has to be analysed with care; not only for its non-linear behaviour. Notwithstanding its complexity, such a model could capture our best understanding of the functioning of the ocean-human intersections through appropriate mathematics. As such it may be a useful research tool.

However, for any index to be a useful management tool (e.g. how to value different resources or options) the method how the score of the index is calculated needs to be understandable. Therefore, the mathematical complexity of the composite model may be too high, and many users may prefer the method "weighted arithmetic average". Rickles and co-workers [2] show how the score of the index depends on the mathematical method.

[2], [f]: for references see "One Ocean, One Index – a 'Composite Essay' on Opportunities and Limits" 

One Ocean, One Index – a 'Composite Essay' on Opportunities and Limits.

Avant propose

How to manage assets that jointedly provide a common resource? How to measure health of the commons? How to assess a composite of assets? How to assess changes of a composite? To consider these questions one may turn to indexes as descriptors, or even to a single index that is designed to provide a middling representation. This kind of descriptors, such as the "Gross Domestic Product per Capita" [#] to name one of the most widely used indexes, appeal to provide first-hand guidance for management options and policy choices. That is their charm and their risk.
Common sense, practitioner's wisdom and expert's knowledge allows to appreciate limitations of indexes and thus may guide their appropriate use. In that sense the ocean-health index illustrates manager's dream and manager's headache, or implications of a simple choice: “using the arithmetical average”.
[#] averaging economic contributions weighted by their monetary value over a group of people


Since the last 3.5 Billion years the ocean, possibly is the essential ecosystem-service-provider of Earth. The ocean produces half of the free oxygen in the atmosphere, stabilises our climate and facilitates plate tectonics. The ocean is a global resource exploited by humankind. The interplay between humankind's economy and marine ecosystems can be described as "the human-ocean system". The ocean is beneficial for societal wealth and human development. It offers access to food, materials, energy, and recreational opportunities. Therefore managing the human-ocean system in a sustainable manner, is paramount to maintain the "health of the ocean".
Many states have policies to ensure their access to marine resources often using a "blue" catch-word to advertise their policies. "The 'Blue Economy' concept has attracted much interest in international fora and become a key to development strategies of international organizations. This cross-cutting initiative aims to provide global, regional and national impact to increase food security, improve nutrition, reduce poverty of coastal and riparian communities and support sustainable management of aquatic resources.”[a]
Regional seas are theatres of competing economic interests that significantly influence the stage of the global ocean. Already today, many seas are in a poor state. Overfishing shifts balances of ecosystems. Pollution caused by extractive industries threatens living resources. Marine litter spoils recreation. Plastic disrupts marine life along the entire food web with eventual health effects on humans. Alterations of coastal zones destroy unique habitats and resilience of living spaces, etc. Rapid deployment of advanced technologies enables penetration and extraction of resources in areas previously too harsh or difficult to get to. And thus, are eliminating the last natural refuges of marine life and this without adequate "compensation" by marine sanctuaries.
On one side, the risk is high that widespread implementation of “blue economy strategies” will increase the general pressure on marine environments. On the other side, treating the marine environment as a jointly managed common resource increases the possibility to foster its sustainable use. Management however needs standardized tools; e.g. to compare options. In that context, a means to assess the ‘health of the ocean’ in a standardized manner would be much appreciated.
Drawing on experiences in coastal zone management, comprehensive assessments of the marine environments are emerging. These assessments consider a composite of oceanic features that influence societal wealth and human development. Nowadays a wealth of information on marine systems is available. Our understanding of marine systems still may be incomplete, but a tentative assessment of global ocean-health issues is possible. Against this backdrop, when proposing a comprehensive ocean-health index [1] and making it available [b] Ben S. Halpern and co-workers pioneered a sustainable human use of the ocean. Annual assessments are published using the best available science and comprehensive data. 

Recently Wilfried Rickels and co-workers [2] scrutinized the mathematical method that is used to calculate the score of the index; showing that the score varies depending on the method that is used. Their analysis shows that perplexing issues are hidden in the use of apparently very simple methods; that is what this essay attempts to discuss as "manager's dream or manager's headache"; see the sections:

Post Scriptum

How to generalize this experience? What has been discussed above for the ocean health index applies mutatis mutandis to other indices that are calculated as a single score for a composite of assets that can substitute each other.

Reference for all sections:
[c] The single assets of the ocean-health index are: (1) Artisanal Fishing Opportunities, (2) Biodiversity i.e. species and habitats, (3) Coastal Protection, (4) Carbon Storage, (5) Clean Waters, (6) Food Provision i.e. fisheries and aquaculture, (7) Coastal Livelihoods & Coastal Economics, (8) Natural Products, (9) Sense of Place i.e. iconic species’ and special places, and (10) Tourism & Recreation [x].
[e] http: //

[1] An index to assess the health and benefits of the global ocean (2012). Benjamin S. Halpern, Catherine Longo, Darren Hardy, Karen L. McLeod, Jameal F. Samhouri, Steven K. Katona, Kristin Kleisner, Sarah E. Lester, Jennifer O’Leary, Marla Ranelletti, Andrew A. Rosenberg, Courtney Scarborough, Elizabeth R. Selig, Benjamin D. Best, Daniel R. Brumbaugh, F. Stuart Chapin, Larry B. Crowder, Kendra L. Daly, Scott C. Doney, Cristiane Elfes, Michael J. Fogarty, Steven D. Gaines, Kelsey I. Jacobsen, Leah Bunce Karrer, Heather M. Leslie et al., Nature 488.

[2] How healthy is the human-ocean system? (2014). Wilfried Rickels, Martin F. Quaas and Martin Visbeck. Environmental Research Letters Vol. 9(4). doi:10.1088/1748-9326/9/4/044013

The Ocean Health Index - summary & revisited

One Ocean, One Index – a 'Composite Essay' on Opportunities and Limits.

The Ocean Health Index – summary: Ten amalgamated assets
To set up the ocean-health index, Ben S. Halpern and co-workers identified ten "assets" of the human-ocean system [c]. The assets are ranging from "Artisanal Fishing Opportunities" and "Biodiversity" through "Carbon Storage" and "Food Provision" to "Sense of Place" and "Recreation". The assets were selected to cover a wide range of ecological, social, and economic benefits or 'use cases'; in that sense they are a possible choice but not necessarily the most obvious. Some of the assets are composites of sub-assets.

To calculate the index, a composite assessment of the state of each asset is undertaken that is applying reference values, studying current situations and development paths. A score is calculated for each asset, and finally one single number, the average score of the ocean-health index, is calculated. That number describes the state of the human-ocean system as a "composite-asset". Obviously, if different composites of result in the same average score then the index indicates a comparable "healthiness" of the human-ocean system.
Considering mathematics, the average score for the ocean-health index is calculated as the weighted arithmetic average of the individual score of each asset. That choice and its implications will be the subject of the following discussions.
However, before turning to that subject following has to be stressed: Selecting these ten assets, identifying indicators for each, gathering data measuring the indicators is a tedious and complex undertaking. That process itself gives ample space for biases, nuanced choices or simple errors. Improving the ocean-health index is a very valuable subject of research and study. Attempts to improve the index do not render it meaningless; they will, on the contrary, strengthen its role as a means for global benchmarking and comparison that otherwise would be missing. Wilfried Rickels and co-workers discuss methodological improvements, while recognising the legitimacy of the data on which it is based. However, these improvements have other limitations that argue for the initial approach of Ben S. Halpern and co-workers.
The annual ocean-health index is calculated at regional level, for coastal seas or Exclusive Economic Zones of countries, for high sea areas, and at global level for the world ocean. For 2012 to 2014, the score of the ocean-health index for the world ocean was estimated to be a modest ~65 of 100. The score for Exclusive Economic Zones of different countries varies between "below 50" and "above 90". Compared to the average score the scores for individual assets may differ considerably. For example, Belgium scores about 100 for coastal protection scores, about 30 for tourism/recreation and has an average score of around 80 for its EEZ.
The index is designed to compare different natural and economic settings and different choices how countries manage their Exclusive Economic Zones. Thus the question arises what is implied when the average score of the ocean-health index for the EEZ of Norway and Netherlands is about 80 and the average score for Iceland's EEZ is about 70. Looking for detail, e.g. what are the scores for single assets, one notices that the scores for single assets vary in a different manner for each of the countries.
In face of these variations the question arises, what kind of simple guidance a manager or the public can get. Consequently one may turn back to the average score and conclude: Norway and Netherlands manage their EEZ equally well and, overall, a bit better than Iceland. If correct, than this is a bold statement. Consequently the question moves into focus "how the average score is obtained?"

The Ocean Health Index – revisited: intermediate level of substitution
Recalculating the ocean-heath index with a modified methodology to estimate the average score [2], showed a considerable dependence of the ocean-health index on the choices for the substitution possibilities including substantial swings of countries between camps of comparatively "well-performing countries" and "under-performing countries". The bulk result of the study [2] is that the global ocean-health index decreases by 20%; namely from a score of 65 of 100 to the score of 52 of 100 if the "weighted arithmetic average" is replaced by a revised methodology limiting substitution among assets. The revised index reduces less-realistic possibilities for offsetting poorer performances in certain assets by better performances in other assets. The associated drop of the global ocean-health index is important, and possibly many decision makers, who would find a score of 65 of 100 "still tolerable" - two good for one bad -, would modify that view for a score of 52 of 100.
Even more striking is the finding [2]:“...when we turn to the assessment of individual countries. Countries with an unbalanced performance across the assets significantly deteriorate in the ranking compared to countries with a balanced performance. For example, Russia and Greenland fall in the ranking for 2013 by about 107 and 118 places (out of 220) respectively, while Indonesia and Peru improve by about 78 and 88 places respectively.” Similarly striking changes are observed regarding the assessment of change over time, for one out of four countries the direction of change is inverted.

These changes of the score of the index in function of the mathematical method is worrisome. An overall shift of scores likely is a simple feature with less impact on management choices. However inverting either relative ranking positions or trends are changes that put in question the usefulness of the index as management tool.

Main-streaming Interest in Earth Science Topics

Call for Contribution - Annual Assembly European Geosciences Union

12-17 April 2015  Vienna


Session EOS 9: Main-streaming Interest in Earth Science Topics

Convener: Martin Bohle with Marion Burgio, Giuseppe Di Capua, David  Grinspoon, Jesús Martinéz-Frias, Cornelia Nauen 
Participants at this session will explore experiences how to mainstream curiosity for earth science topics or how to appraise them as a matter of public interest.

Participants are invited to tease out lessons how to achieve main-streaming curiosity for earth science topics, addressing both successful outreach activities and obstacles. Experiences from diverse approaches are welcome; i.e. using traditional or modern media or engaging with arts or story-telling. Deliberately, the perspective on valuing earth science topics is cast widely: inviting perspectives on the beauty or particularity of ordinary or special phenomena, evaluating hazards for or from mundane environments, or connecting the scholarly investigation with concerns of citizens at large.

The following reflections illustrate how experiences from a wide range of earth science topics might be woven into common threads of the session: 

"Weather" is the earth science topic that gains regular attention in "prime-time", and consequently, meteorology is among daily interests of citizens. Why have other earth science topics not received the same sort of interest? Was it essential that since the early 1950-ties the public discussion of weather benefited from broadcasting of weather forecasts? What other examples exist and might inspire opportunities for connecting earth science topics more firmly with citizens' interests?
    Earth sciences are relevant for knowledge societies: in addition to provide insights into the functioning of Earth's systems, they permit looking into the evolution of live-bearing planets and the impact of humankind's activities on biogeochemical systems on Earth. When discussing how to main-stream earth science topics into the daily interests of citizens, participants may consider both, the bearing of earth sciences topics on economy, living conditions and individual well-being, and citizens' experiential connections to earth science topics.

    Most traditional earth-centric story-telling of rural societies has disappeared in the global urbanisation process. However, the relevance of understanding functioning of the Earth has increased, be it for economy or values adapted to the Anthropocene. In the last decade a public discussion of anthropogenic global change and geoengineering took off building on the discussions about weather and hazard mitigation, but also weaving demographics, linguistics and cultural histories into a richer narrative of change. What teach such interdisciplinary explorations for main-streaming interest in earth science topics?