Environmental Systemic Risks

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Biological stress factors, environmental risks

The first version of this article was made in 2004/2005, the interdiscipline called "Earth System Science" was still in the making, it only appeared on Wikipedia in 2009.

On an international scale, setting up programs to set up indicators, map and monitor all the systemic risks that could weigh on the planetary environment will appear - more and more - as a major priority.

It is interesting to note that these risks - over the years - are gradually taken into account, especially where long-term societal and economic issues are observed (World Forum, UN).

Direct measures of biodiversity

Biodiversity responds to the pressure that the environment exerts on living beings. The measurement of this biodiversity indirectly makes it possible to measure biological stress.

In the current state of knowledge and means of measurement, it seems difficult to assess biodiversity on the scale of entire regions: this cannot be envisaged other than locally. There are a few methods for this:

  • Abundance biomass comparison method (ABC): calculation of the level of disturbance (Clarke and Warwick, 2001a)
  • Shannon or Shannon-Wiener (H') diversity index (Pohle et al. 2001)
  • Species abundance curve
  • Average taxonomic distance (AvTD) and variation in taxonomic distance (VarTD) (after Clarke and Warwick, 2001b): their average values ​​are independent of the sampling effort: the response to increasing environmental stress is monotonic (i.e. it decreases or increases with the level of disturbance)

Biodiversity responds to the environment and the pressure it exerts; if such that within the framework of this study we are interested precisely in what disturbs this biodiversity, it is not necessarily useful to measure it directly, but rather to be interested in the pressures which the environment exerts.

This is assessed by listing the sources of biological stress.

Biological stress

It is expressed by attacks on the environment, it promotes the development of certain species to the detriment of many others. A "stressed" ecosystem will respond by an impoverishment in the absolute number of species to the benefit of a few that will occupy the most affected or even disappeared ecological niches.

Species average ranked abundance (or dominance) curves (a) and ranked cumulative abundance curves (k dominance curves) (b), for samples from weathered stations located near (dashed line) an operation of oil drilling and relatively unaffected stations (solid line), representing populations under different types of biological stress (after Clarke and Warwick, 2001a).

Abundance-biomass comparison(h6b585ku) (ABC) method for calculating the level of disturbance, from the comparison of curves of biomass (specific) and abundance (dominance k), showing the relative positions of the curves at different pollution levels (after Clarke and Warwick, 2001a).

"abundance": % of individuals of species i
"biomass": % of the biomass represented by species i

Environmental Vulnerability Index (IVE)

Drawing up a list of vulnerabilities is a task that should increasingly preoccupy future generations, all the more so as they will increasingly be confronted with global climate change.

For example, the Environmental Vulnerability Index (EVI) is a measure that was devised by the South Pacific Applied Geosciences Commission (SOPAC), the United Nations Environment Program to characterize the relative severity of various types of problems environmental conditions suffered. EVI results are used to focus on planned solutions to negative pressures on the environment, while promoting sustainability.

These vulnerabilities are articulated according to a logic in 3 levels (cf, following chapter):

  • Original environmental system(s)
    • Disturbing natural or man-made factors (stress)
      • measurable indicators

Also see Environmental Vulnerability Index on Wikipedia.

Examples of stressors

  • climatic phenomena,
  • Rainfall,
  • Droughts,
  • amount of heat,
  • Storms,
  • Gels,
  • Pollution,
    • boreholes,
    • Acid rain,
    • Mutagenic elements, electromagnetic radiation ,
    • Change in dissolved oxygen concentration,
  • Fires,
  • Biological balances,
    • Nutrient content in food,
  • Geological phenomena,
    • Volcanic eruptions,
    • Avalanches,
    • Landslides, ...

Examples of measured variables

In any case, from these environmental factors, it is a question of finding measurable indicators and managing to identify the most important factors. It is necessary that these are measured over sufficiently long durations to be considered "relevant/critical". For example:

  • Modification of the ph level,
  • Sulphate concentration (SO4/SO2),
  • Concentration of phosphorus / Phosphates (P/PO4),
  • Nitrogen concentration (N/NO3),
  • Vertical and horizontal concentration of ozone (O3),
  • Active radiation for photosynthesis,
  • Air temperature at the surface of the oceans (by satellite),
  • Measurement of chlorophyll concentrations,
  • Concentrations of dust in the atmosphere,
  • CO2 rate, ...

Classification of Environmental Systems

We can classify environmental risks according to their environmental sphere of origin. On U-Sphere this division was made:

  • The Heliosphere, the Magnetosphere,
  • Atmosphere,
  • The Litosphere,
  • The Hydrosphere, Cryosphere,
  • The "Cosmosphere",
  • The Anthroposphere


Generally, volcanic dusts or explosions create a cooling of the earth's atmosphere, because reflecting a certain part of the solar energy in space and cooling the earth. However, very energetic cosmic rays do not interact much, but when this happens, they break the molecules of the upper atmosphere, typically CO2. This thwarts the greenhouse effect, and on the other hand, the broken molecules will recombine to form clouds of water vapor which will modify the alabedo of the planet and cause imbalances.

  • Meteors, Comets

The Solar System is crossed by objects of different sizes that could represent a major risk for the Earth. These risks escaped until now any possibility of control, today the space agencies and NASA in particular set up surveillance programs like Sentry II.

Heliosphere, Magnetosphere

Le soleil est à l'origine d'un grand nombre de phénomènes pouvant impacter l'environnement Terrestre

The variability of solar activity and the little hindsight humanity has makes this risk still largely neglected.

Surface du sun

Solar Plasma

Radiations from the sun

Interplanetary Magnetic Field EM fields generated by solar plasma (/EUV?)


Essentiellement une interface de stokage des aérosols, particules et de transformation de ceux-ci sous l'effet des températures et du rayonnement solaire.

Outre les phénomènes climatique, l'atmosphère est un médiateur pour un ensemble de phénomènes liés à l'activité humaine.

Hydrosphère, cryosphère

  • Sécheresses,
  • Innondations,
  • Tsunamis,
  • Vitesse de fonte des glaces,
  • Modification des cours d'eau ou des plans d'eau,
  • Taux d'oxygène, de CO2 dissous, ...


Il s'agit ici de rétroactions liées à l'activité des espèces vivantes en relation avec les modifications environnementales et la modification d'équilibres.

  • L'eutrophisation,
    • augmentation de la biomasse algale,
    • augmentation de la biomasse du zooplancton gélatineux,
    • dégradation des qualités organoleptiques de l'eau (aspect, couleur, odeur, saveur),
    • développement de phytoplancton toxique,
    • diminution de l'indice biotique,
    • diminution de la concentration en dioxygène dissous,
    • mort des organismes supérieurs (macrophytes, insectes, cnidaires, crustacés, mollusques, poissons, etc).
  • la modification des courants marins.

(Ces causes n'étant pas strictement liées à l'hydropshère mais liées à des facteurs humains et écologiques exogènes)

Marqueurs/variables liées

  • biodiversité du plancton

il est essentiel à la biodiversité des espèces qui s'en nourissent, mais aussi pour répondre aux variations spatiales et temporelles des contraintes environnementales. Ainsi, la qualité d'un écosystème marin peut se baser sur la qualité du spectre "planctonique" (zooplancton et phytoplancton)

  • croissance des coraux

ce sont des marqueurs du climat passé et des niveaux de pollution.


Il s'agit de mesurer l'empreinte systémique au travers des activités humaines.

  • Zones de décision et de contrôle (gouvernements, centres de commandement),
  • Zones de pollution et de contamination:
    • Nucléaire,
    • Bactériologique,
    • Chimique et industrielle,
  • Zones d'exploitation des ressources :
    • Ressources naturelles (encore) disponibles,
    • Exploitation des ressources naturelles / biologiques,
    • Contamination du milieu écologique,
    • Destruction des espèces, des habitats,
  • Zones de conflit


  • Tectonique des plaques
    • Volcanisme,
      • Poussières et gaz >> atmosphere
    • Tremblements de terre,
      • Tsunamis,
  • Inclinaison, Précession, Ecliptique

Couplage des risques et des flux

File-vsd.gif biosphere-risques.vsd

Biosphère, couplage des risques environnementaux

Attitude de l'homme face aux risques systèmiques

Un plan stratégique de surveillance

La survie de l'espèce et des équilibres environnementaux dépend en amont de la surveillance des paramètres listés précédemment.

L'environnement agit sur l'homme et en retour l'homme agit sur l'environnement : les facteurs d'évolution sociale sont donc à prendre en considération.

De même, l'évolution des moyens scientifiques et techniques (Technosphère) vont peser dans les interactions entre l'homme et son environnement, sur sa capacité à modifier l'environnement dans lequel il vit.

Voici donc des paramètres supplémentaires qu'il faudrait prendre en compte :

Développement humain

  • Industriel,
  • Démographique,
  • Social,
  • Idéologique,
  • Scientifique,
  • Biologique de l'espèce.

Capacités de réaction de la société

  • Tendances psychosociales à la soumission,
  • Tendances psychosociales à la conservation des attitudes,
  • Subordination de la Technologie.

Nous réalisons ici un parallèle entre cette surveillance et la surveillance que pourraient réaliser d'autres espèces intelligentes dans l'univers, dans l'objectif de leur survie et/ou de la compréhension des systèmes écologiques qu'elles sont susceptibles de rencontrer.