Planetary boundaries

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Visual representation of the extent to which the planetary limits are currently exhausted or exceeded (according to Will Steffen et al., 2015)

As planetary boundaries (even planetary boundaries, or load limits of the earth; English planetary boundaries ) are ecological referred to the earth, beyond which the stability of the ecosystem at risk and the livelihood of mankind. Currently, nine planetary boundaries are mostly being discussed, which are intended to define a safe scope for mankind, but several of which have already been exceeded.

The concept of planetary boundaries is part of the future scenarios with regard to global environmental changes . It was originally developed by a group of 28 Earth system and environmental scientists led by Johan Rockström (Stockholm Resilience Center) and first published in 2009. The authors include Will Steffen ( Australian National University ), Hans-Joachim Schellnhuber ( Potsdam Institute for Climate Impact Research ) and Nobel Prize winner Paul Crutzen .

Compliance with planetary boundaries has already been partially adopted as a goal by international climate policy , e. B. with the two-degree climate protection barrier . It is also the basis of the main report of the WBGU from 2011 with the title World in Transition - Social Contract for a Great Transformation and has become the basis of the concept of planetary health .

concept

background

As early as 1713, Hans Carl von Carlowitz formulated the concept of sustainability in his work Sylvicultura oeconomica on forestry . As a reaction to local environmental changes, the first approaches of an environmental movement emerged . It was not until after the Second World War , however, that global environmental changes and future scenarios began to be systematically and scientifically investigated. The Club of Rome's report " The Limits to Growth " presented the effects of unlimited economic growth . This led to concepts such as qualitative growth , green economy , green growth or Green New Deal and, on the other hand, to an ecologically motivated growth critique and the emergence of a growth critical movement .

The original research project on planetary boundaries refers to the concept of the Anthropocene , according to which the geological age of the Holocene has been replaced by a new age since the industrial revolution due to the influence of humans on the earth . In the past 10,000 years of the Holocene, the earth is in a relatively stable state and global fluctuations in biogeochemical and atmospheric quantities only occurred within a narrow range. However, since the industrial revolution, some of these quantities have moved outside the expected variance. This is attributed to the influence of the human species on the Earth system processes. Science therefore asks itself the question of the absolute, non-negotiable biophysical limits on a planetary level, compliance with which ensures the continued existence of humanity and prevents serious global environmental changes. For this purpose, as already done by the German Advisory Council on Global Change (WBGU), from 1994 onwards, using the concept of planetary guard rails, existing research results from Earth system sciences were brought together and summarized under the concept of planetary boundaries.

Research history

Ecological load limits according to Rockström et al. 2009

In 2009, a group of scientists from the fields of earth systems and environmental sciences published an initial overview of the limits of ecosystem services. In addition to Johan Rockström and Will Steffen , the 29-person research group also included Nobel Prize laureate Paul Crutzen and the chairman of the German Advisory Council on Global Change (WBGU) Hans Joachim Schellnhuber . A short version was published in the journal Nature in September 2009 . In doing so, they determined nine planetary boundaries, each of which is essential for the continued existence of the human species. They also determined the quantitative limits for seven of the nine areas and gave an estimate of how far they have already been exhausted. It was found that three limits had already been exceeded at the time of the first publication.

An updated report from the group was published in Science magazine in January 2015 . In this, the planetary boundaries were partially revised and updated with current data. The report was presented in 2015 at the World Economic Forum in Davos .

The planetary limits

description

The planetary boundaries are intended to define a "safe space for maneuver" for human actions on earth. Certain threshold values ​​must not be exceeded or fallen below in order not to endanger the resilience of the earth as a system. In some processes there are tipping elements in the earth system , where exceeding them would cause abrupt and irreversible changes. The planetary boundaries are defined in such a way that, according to the current state of knowledge, there is only a very low probability of crossing tipping points or overloading the resilience of the earth system. The “safe room for maneuver” is followed by a “zone of uncertainty” because, firstly, the limit values ​​cannot be precisely determined due to the complex interrelationships and, secondly, mankind should have time to act before reaching a planetary limit. In addition, the inertia of certain Earth system processes (e.g. the climate system) must be taken into account, where changes require time to take effect. This is followed by the "dangerous zone", in which there is a high probability that the earth system will be impaired. Crossing a planetary boundary does not mean that the earth system is affected as a consequence, but the risk increases with the degree of crossing of the boundary.

Known planetary boundaries

Eight out of nine known planetary boundaries have already been quantified. Only in the dimensions acidification of oceans and freshwater consumption , the planetary limits are not exceeded. The stratospheric ozone depletion will only be exceeded regionally and temporarily and will tend to decrease. The meaning of the limit and the measurands are then explained in detail for each planetary limit.

dimension Measurand Planetary boundaries Current measured value Load limit exceeded
Climate change CO 2 concentration in the atmosphere ( ppm ) or

Radiative forcing ( watts / square meter )

Max. 350 ppm

Max. +1.0 W⋅m −2

405 ppm

1.43 W⋅m −2

Yes
Ocean acidification Mean global aragonite saturation in surface water (Omega units) min. 2.75,

(80% of the pre-industrial value)

3.03

(88% of the pre-industrial value)

No
Stratospheric ozone depletion stratospheric ozone concentration ( Dobsonian units ) min. 275 YOU 220-450 DU regional and temporal yes
Atmospheric aerosol pollution Aerosol optical thickness (without unit) no global limit

South Asia: max. 0.25

-

South Asia: 0.3-0.4

-

regional yes

Biogeochemical cycles Phosphorus cycle Global: Phosphorus input into oceans ( teragrams / year )

Regional: phosphorus input into freshwater systems ( teragrams / year )

Global: max. 11 Tg yr −1

Regional: max. 6.2 Tg yr −1

Global: 22 Tg yr −1

Regional: 14 Tg yr −1

Yes
Nitrogen cycle Industrial and intended biological binding of nitrogen ( teragrams / year ) Max. 62 Tg yr −1 150-180 Tg yr −1 Yes
Fresh water consumption global consumption of surface and groundwater ( cubic kilometers / year ) Max. 4,000 km³ yr −1 2,600 km³ yr −1 No
Land use change Proportion of the original forest area min. 75% 62% Yes
Integrity of the biosphere Genetic diversity Extinction rate (number of species per million per year, E / MSY) Max. 10 E / MSY 100-1000 E / MSY Yes
Functional diversity Biodiversity Intactness Index (BII) min. 90% 84% for southern Africa regional yes
Introduction of novel substances No control variable or limit defined so far.

Climate change

The planetary boundary “ climate change ” aims to minimize the risk of climatically induced and potentially irreversible changes in the earth system. The boundary setting takes into account disturbances in regional climate systems, influences on important climate dynamics patterns such as thermohaline circulation, and other effects such as the rise in sea level .

Steffen et al. used a two-part approach to setting boundaries. On the one hand the atmospheric CO 2 concentration is used, on the other hand also the global radiative forcing . Although radiative forcing is a comprehensive variable (taking into account the total anthropogenic emissions that affect the earth's energy balance), CO 2 is still set as an additional limit. This is due both to the long residence time of the molecules in the atmosphere and the large amount of emissions by humans.

The currently set limit for CO 2 is 350 ppm (uncertainty zone: 350–450 ppm), at a concentration of currently (2017) 405 ppm. For global radiative forcing , the limit was set at +1.0  watts per square meter (W⋅m −2 ) compared to the pre-industrial age (uncertainty zone: +1.1–1.5 W⋅m −2 ). The current global radiative forcing was estimated by the NOAA (National Oceanic and Atmospheric Administration) to be 3.06 W⋅m −2 or 1.43 W⋅m −2 in comparison to the pre-industrial age. Accordingly, both values ​​and thus the planetary limits of "climate change" have already been exceeded.

Ocean acidification

The planetary boundary “acidification of the oceans” is closely linked to the boundary of climate change. The oceans serve as a carbon sink, both through direct dissolution of CO 2 in water and through the uptake of carbon by aquatic organisms. An increase in the CO 2 content in the oceans leads to acidification (lowering of the pH value ) of the upper seawater - this is synonymous with a decrease in the concentration of carbonate ions in the water. However, numerous organisms, such as corals or mollusks , require dissolved calcium carbonate, from which they form their shells and / or skeletal structures in the form of aragonite or calcite . If the content of carbonate ions in the water and thus the saturation of calcium carbonate falls below one, the calcium carbonate dissolves from the shells of marine organisms. Since aragonite has a greater solubility than calcite, this planetary limit regards the saturation value of aragonite in sea water as a decisive variable (Ω arag ).

The threshold value for the dissolution of the structures of organisms is Ω arag  = 1. However, severe impairments of the organisms are to be expected well before this is reached. The proposed limit should therefore be 80% of the annual average pre-industrial value of Ω arag   = 3.44. However, it must be taken into account that the saturation value of aragonite fluctuates both locally and over time. A study from 2015 puts the current value (area- weighted global annual mean) at around 88% of the pre-industrial level (Ω arag  = 3.03).

Stratospheric ozone depletion

Ozone in the stratosphere filters ultraviolet light from solar radiation. This is of crucial importance for living things on earth, as it can damage the DNA and thus have a carcinogenic effect. A sufficiently strong ozone layer filters certain wavelengths of UV light.

Certain substances lead to the breakdown of ozone in the stratosphere and thus to a reduction in the protective effect. These include a. Chlorofluorocarbons (CFCs). Furthermore, natural phenomena such as polar stratospheric clouds contribute to ozone depletion. The thickness of the ozone layer is measured in DU, Dobson units . A value below 220 DU is called an ozone hole . Typically, the largest ozone holes occur during the Antarctic Spring in the southern hemisphere, after the ozone-depleting substances accumulated over the winter are released by the sunlight in the spring.

The by Steffen et al. The proposed planetary boundary refers to the areas outside the polar region, as these are affected by regional effects, but significantly more serious effects on people and ecosystems are to be expected outside the region. A specific number is given as a limit of 275 DU, with the addition that for each degree of latitude the value must not be less than 5% of the comparative mean value from 1964 to 1980. Current values ​​outside the polar regions are well above the limit value. During the Antarctic spring, however, the polar regions sometimes fall well below the 200 DU mark.

With the ban on CFC gases in the Montreal Protocol , the ozone layer has been recovering steadily since 1989. The limit of the stratospheric ozone depletion is thus a first example that after a one-off regional exceedance, a return to the safe area of ​​action is possible through human efforts.

Atmospheric aerosol pollution

Aerosols in the atmosphere can affect both the climate system and human health. They influence cloud formation and the greenhouse effect via the albedo , but they are also the cause of acid rain. Aerosols also cause respiratory diseases in humans. In addition, they are often not tied to a specific region, but are passed on over great distances from the place of origin to the place of activity. A quantifiable planetary limit was not specified by Steffen and Rockström in their original contribution, because too many uncertainties and dependencies play a role in the formation and effect.

In their revised contribution to the planetary boundaries of 2015, the measurement of aerosol pollution via aerosol optical thickness (AOD) was proposed, a measure of the attenuation of solar radiation when particles pass through the atmosphere. Example measurements in South Asia showed that the normal aerosol load corresponds to an AOD of 0.15 and increases to approx. 0.4 due to human emissions from heating or combustion engines, for example. Since an influence of the aerosols on the monsoon rain events in the region could be observed from an AOD of 0.35, the limit (regional) was set at 0.25. Current values ​​for the region are between 0.3 and 0.4 and have an increasing tendency in numerous subregions, so that this limit must also be viewed as exceeded. A global (planetary) boundary cannot yet be determined due to the regionally specific effects.

Biogeochemical cycles

Phosphorus and nitrogen have become almost indispensable as fertilizers in agriculture , but also in industrial use. The influence on the ecosphere caused by the excessive application of these substances should be quantified in this limit.

In their 2009 contribution to the planetary limits, Steffen et al. considering the possibility of setting a separate limit for both the phosphorus and nitrogen cycles. Due to the close connection and the mutual influence of the two material flows, a single limit with two limit values ​​(each for nitrogen and phosphorus) was created. The original designation “disruption of the N and P circuits” was replaced in the 2015 revision by simply naming the circuits under consideration, as it cannot be ruled out that further elements will have to be considered within this limit in the future.

Phosphorus cycle

The first part of the boundary of the biogeochemical cycles relates to the influence of phosphorus on the biosphere. Phosphorus is a degradation product, but under natural circumstances it enters the biological cycle through weathering processes. In the original contribution by Steffen et al. the entry of phosphorus into the oceans was set as the main criterion for the limit. It is intended to reduce the likelihood of an oxygen depletion in the oceans ( oceanic anoxic event ) and thus a mass extinction of marine life. The limit of 11 Tg P yr −1 ( teragram of phosphorus per year) was set at 10 times the value of the natural weather rate. A possible OAE should therefore only become probable in over 1000 years. The current value is estimated by Steffen et al. to about 22 Tg P yr −1 .

In addition to the global phosphorus input, a regional limit was added in the 2015 article. It is intended to limit the entry of phosphorus into water bodies on a smaller scale, mainly through the use of fertilizers. Therefore, the global agricultural areas in particular contribute to a large part of the phosphorus input rate. The limit of 6.2 Tg P yr −1 of entry into freshwater systems set by the scientists has already been exceeded in numerous regions as of 2018, in some cases by more than double (> 14 Tg P yr −1 ).

Nitrogen cycle

The nitrogen cycle is influenced by numerous anthropogenic processes. Atmospheric nitrogen is bound in ammonia production , but the cultivation of nitrogen-fixing plants ( legumes ) also contributes to nitrogen fixation. Burning fossil fuels and biomass releases nitrogen into the atmosphere. The effects of nitrogen are varied and depend on the compound entered into. As laughing gas (N 2 O), for example, it contributes directly to the greenhouse effect as one of the most powerful climate-affecting gases. It collects as nitrate (NO 3 - ) in waters and soils. Nitrate can be converted into nitrite by certain bacteria, which is toxic to numerous organisms.

Steffen et al. suggested in their first contribution limiting global nitrogen input to around 35 Mt per year, which was around 25% of the input at that time, without any further scientific assessment. In their revised concept, the limit was defined as "industrial and intended biological fixation" and set at a value of 62 Tg per year. In doing so, they adopt the calculations of de Vries et al., Who do not consider a limit of 35 Tg per year to be feasible due to the need for nitrogen as a fertilizer in food production. Current values ​​of nitrogen input range from 150 Tg N yr −1 to around 180 Tg N yr −1 , which means that this limit is more than doubled.

(Fresh) water consumption

The water balance has a major influence on the functions of the earth system. Water has an impact on food security and the habitat of many species. It is also of great importance for climate regulation. For better differentiation, Steffen et al. between water stored in the ground (so-called green water) and surface and ground water (so-called blue water). Both types of water are closely linked through the water cycle . The evaporation of soil moisture in the atmosphere creates water vapor , which turns into blue water again in lakes and rivers through precipitation . In turn, irrigation turns blue water into green. A limit to fresh water consumption must therefore be set in such a way that there is enough green water to maintain soil moisture and stimulate precipitation, but at the same time enough blue water to maintain aquatic ecosystems such as lakes flows away.

In order to reduce the complexity, the consuming use of blue water was chosen as the planetary limit of fresh water consumption. The amount was set at 4000 km 3 per year. Current values ​​assume a world consumption of around 2600 km 3 / year. It is predicted that the consumption of blue water for irrigation for food production will increase by 400–800 km 3 / year by 2050 . Exceeding this limit is therefore not expected.

Further restrictions on this limit were made in the 2015 concept. Since rivers carry different amounts of water over the course of a year, for example due to rainy and dry seasons, an upper limit for water withdrawal was set as a percentage of the average monthly flow for different times. In times of low flows, a maximum of 25% of the average monthly flow per month should be withdrawn, in times of high flows 55% of the average monthly flow may be withdrawn per month. The aim is to ensure that the dependent ecosystems can be supplied with sufficient fresh water even in dry periods .

Land use change

Originally, this limit represented the proportion of the agricultural area used worldwide. An increasing proportion of the ice-free areas is used for food, feed and energy crop production, often in monocultures. The resulting side effects include influences on numerous other planetary boundaries, such as the integrity of the biosphere, biogeochemical cycles and freshwater use. Steffen et al. suggested limiting agricultural areas to 15% of all ice-free areas, with 12% being used for agriculture as of the first publication in 2009.

In the updated concept, the focus of this limit was placed on the proportion of the forest-covered area. The reason for this is the important role of forests on climate regulation, e.g. B. by evaporation effects of tropical rainforests or the influence on the reflection effect of boreal coniferous forests. Since forests are also cleared for non-agricultural uses, the limit is aimed at the proportion of existing forest areas and no longer the proportion of agriculturally used areas. Specifically, the limit is set at 85% coverage for tropical and boreal forests and at 50% coverage for forests in temperate latitudes. In addition to the regional boundaries, the global mean value of the forest types is used as a limit and is set at 75% (as a proportion of the pre-industrial global forest area). Steffen et al. quantified the degree of coverage to 62% in 2015, which would have already exceeded the limit. The FAO puts the annual loss of forest area at around 0.13%.

Integrity of the biosphere (formerly loss of biodiversity)

In the original concept by Steffen et al. the limits of biodiversity loss were introduced. Large changes in biodiversity can have serious effects on the functions of the Earth system. However, many of the consequences of the extinction of certain species cannot yet be estimated because the interdependencies and interdependencies in the biosphere are very high. It is also expected that there will be certain tipping points, beyond which the entire system of the biosphere will collapse.

To determine the loss of biodiversity, the extinction rate E / MSY (Extinctions per million species and year) was proposed. The background mortality rate - the extinction of species without human influence - was estimated by paleontologists to be around 0.1–1 U / MSY. The disadvantage of this measured variable is the low accuracy and the time lag in the determination.

For a more differentiated view, Steffen et al. In the 2015 concept, the planetary boundary was divided into the sub-boundaries “genetic diversity” and “functional diversity”. In addition, the name was changed to "integrity of the biosphere".

Genetic diversity

It encompasses the diversity of all genetic material from which the potential for future developments of new life emerges. The more different genetic species there are, the higher the chance of living organisms to adapt to abiotic changes in a more resilient manner due to an enlarged gene pool.

To determine the genetic diversity of the concept is phylogenetic (phylogenetic species variability - PSV) biodiversity proposed. It indicates to what extent species are phylogenetically related to one another and can therefore be used as a measure of the level of genetic diversity. However, since no data are available on a global level, the extinction rate used in the 2009 concept was used and the global limit was set at 10 E / MSY. Current estimates assume that the extinction rate has risen to 100–1000 E / MSY since industrialization, which is equivalent to mass extinction.

Functional diversity

The functional diversity depicts the functionality of the biosphere, which is given by the organisms and their distribution and properties in ecosystems. For this purpose, the control variable of the biodiversity intactness index (BII) is used. It indicates how the population has changed as a result of human influences, such as land or resource use. A BII of 100% represents the pre-industrial state of the biosphere. Human influences can both reduce and increase the BII, so that theoretically values ​​above 100% are possible.

The proposed planetary limit was set at a BII of 90%. However, since the connection between BII and the reactions of the earth system has not been fully clarified, a high uncertainty band of 30–90% was introduced. So far, studies on BII have only been carried out in countries in southern Africa, with the values ​​between 69% and 91% with an average value of 84%.

Introduction of new substances (formerly exposure to chemicals)

The ninth planetary boundary was originally intended to cover exposure to chemicals. These included radioactive elements, heavy metals and a variety of organic, man-made chemicals. Due to their influences both directly on human health and in the interplay with other planetary limits, the introduction of a separate limit for these substances was justified. However, due to the large number of chemicals traded worldwide (approx. 85,000 in the USA , 100,000 in the European Union ), it is practically impossible to quantify a limit value . In the concept of planetary limits from 2009, therefore, only suggestions were made for the introduction of such a limit: either the monitoring of very mobile substances or the setting of limits for certain chemicals based on their effects on health systems of various organisms.

In the revised publication from 2015, chemicals include newly created and modified forms of life as well as nanomaterials and microplastics . Therefore, the authors proposed a planetary limit "introduction of novel substances". No quantified limit is set in the revision either; Instead, it was suggested that chemicals be tested for the following three points prior to authorization and release:

  • The substance has a disruptive effect on earth system processes.
  • The disruptive effect is only discovered when it has become a global problem.
  • The effect is not easily reversible.

On the basis of these properties, previously released substances could be tested and a respective limit set. However, so far there has been no measurement of chemical pollution on a global level, which is why this limit only provides qualitative measures to reduce this pollution.

Developments and criticism

Criticism of the concept

In the original publication of the concept of planetary limits in 2009, only global standards were adopted and global limits were set. This ignored the fact that some processes show great spatial heterogeneity (e.g. nitrogen and phosphorus input). As a result, the limit values ​​have already been exceeded in some regions without affecting global borders.

In the 2015 revision, this criticism was taken into account: “sub-global” boundaries were defined that are in line with global boundaries. These regional boundaries do not necessarily have the same units as the global boundaries and are not included in the graph, but they provide a way of assessing the extent of Earth system use at the regional level.

Suggestions for a tenth limit

In addition to the nine planetary limits developed by Steffen and Rockström, several scientists suggest further limitations, which are referred to as the tenth limit. The ecologist Steve Running proposes the introduction of terrestrial plant production as a measurable parameter and thus a quantifiable limit. Terrestrial plant production (net primary plant production; NPP) includes all plant growth processes that take place on the earth's land surface. These could be quantified and assessed using satellite images. The proposed limit contains aspects of four limits postulated by Steffen and Rockström: land use change, fresh water consumption, integrity of the biosphere and biogeochemical cycles. The NPP of two original borders, climate change and the introduction of novel substances is influenced. Running points out that of the 53.6  Pg of terrestrial plant production per year, only 10% are additionally available for human use, as either the rest is not available because it is protected or inaccessible land, or it is NPP acts through root growth and is therefore unusable. Accordingly, the proposed limit has not yet been exceeded, but there is little room for maneuver for the future.

Casazza, Liu and Ulgiati take a similar approach. They propose to introduce the energy consumption of mankind as a control variable of their developed tenth limit. The researchers also used the net primary production as a limiting factor, but they take into account the energetic value of the NPP of 7.5 ⋅ 10 13 W. Forecasts for the future show strong deviations from each other, but came to the conclusion that the current western lifestyle does not all an estimated nine billion people can be led by the year 2050 without crossing the border.

Environmental footprints and planetary boundaries

Various studies examined the greenhouse gas and other environmental footprints of Sweden, Switzerland, the Netherlands, Europe and the world's major economies, based on the planet's load-bearing capacity. Different methodological approaches were used. The common result is that the resource consumption of wealthy states - extrapolated to the world population - is incompatible with several of the planet's limits. For Switzerland, for example, this applies to the greenhouse gas, biodiversity and eutrophication footprints (due to nitrogen). Not to be equated but related to these studies are comparisons of the ecological footprint (in global hectares) with the global biocapacity.

The donut model

Here is a picture showing Kate Raworth's donut model.
Kate Raworth's donut model with the state of the boundaries visualized

In 2012, economist and Oxfam employee Kate Raworth published a discussion post in which she criticized the restriction of planetary boundaries to ecological dimensions. As an extension to the classic representation of the planetary boundaries, she suggested a circle open on the inside, reminiscent of a donut. Internally, the model shows the lack of social and societal foundations; externally, it continues to show the ecological limits based on Steffen and Rockström. Raworth's key message about her model is that humanity's goal must be to live “inside the donut”. In 2018 she published her book "The Donut Economy", in which the most important social foundations are quantified:

dimension Measurand % Data period
food Malnourished population 11 2014-2016
health Population in countries with child mortality rates (under five years of age) greater than 25 per 1,000 live births 46 2015
Population, in countries with a life expectancy at birth of less than 70 years 39 2013
education Illiterate people (adults over 15 years) 15th 2013
Children between 12 and 15 years without access to schooling 17th 2013
Income and work Population living below the international poverty line of $ 3.10 a day 29 2012
Proportion of jobseekers aged 15 to 24 13 2014
Peace and justice Population living in countries that score 50 or less out of 100 in the Corruption Perceptions Index 85 2014
Population living in countries with a homicide rate of 10 or more per 100,000 13 2008-2013
Political participation Population in countries with a score of 0.5 or less out of a total score of 1 in the voice and accountability index 52 2013
Social justice Population in countries with a Palma Ratio of two or more (i.e. where the richest 10% of people have at least twice as much of the gross national income as the poorest 40%) 39 1995-2012
equality Representation gap between women and men in national parliaments 56 2014
Worldwide income gap between women and men 23 2009
Living Global urban population living in slums in developing countries 24 2012
Networks Population declaring that they are without someone to count on during difficult times 24 2015
Population without access to the Internet 57 2015
energy Population without access to electricity 17th 2013
Population without access to clean cooking facilities 38 2013
water Population without access to drinking water 09 2015
Population without access to sanitary facilities 32 2015

An empirical application of the donut model by O'Neill et al. showed that none of 150 countries simultaneously meets the basic needs of their citizens and achieves a globally sustainable level of resource use.

Planetary limits of agriculture and food

Environmental impacts of agriculture and nutrition in the context of planetary boundaries

The areas of agriculture and nutrition are globally responsible for exceeding four of the nine exposure limits examined. Excessive nutrient inputs into terrestrial and aquatic ecosystems make the nitrogen and phosphorus cycle the most important, followed by excessive land use change and biodiversity loss caused by agriculture and food. Nutrition includes food processing and retailing as well as the preparation of food in households and restaurants. Food-related environmental loads are not quantified for the exposure limits of freshwater use, air pollution and ozone depletion in the stratosphere on a global level.

Political application

Climate policy

The concept of planetary boundaries is already finding its first fields of application. It has already been partially adopted as a goal by international climate policy , e. B. with the two-degree climate protection barrier. However , the authors do not consider the two-degree target to be sufficient to prevent tipping points in the climate system from being exceeded.

Concept of planetary guard rails

The concept of planetary boundaries is the basis of the main report of the German Advisory Council on Global Change (WBGU) from 2011 entitled World in Transition - Social Contract for a Great Transformation . The basic structure of the planetary guard rails there is comparable to the planetary boundaries.

dimension Measurand
Limit global warming to 2 ° C The global CO 2 emissions from fossil sources are to be completely stopped by around 2070.
Limit ocean acidification to 0.2 pH units Global CO 2 emissions from fossil sources are to be completely stopped by around 2070 (ditto climate change).
Stop the loss of biodiversity and ecosystem services The direct anthropogenic drivers of biodiversity loss are to be brought to a standstill by 2050 at the latest.
Stop land and soil degradation The net land degradation is to be stopped worldwide and in all countries by 2030.
Limit exposure to long-lived anthropogenic pollutants
12 mercury The substitutable use and anthropogenic mercury emissions are to be stopped by 2050.
12 plastic The release of plastic waste into the environment is to be stopped worldwide by 2050.
12 Fissile material The production of nuclear fuels for use in nuclear weapons and for use in civilian nuclear reactors is to be stopped by 2070.
Stop loss of phosphorus The release of non-recoverable phosphorus is to be stopped by 2050 so that it can be recycled worldwide.

The ozone hole is no longer viewed as a planetary guard rail. The same thing says in Die Zeit: "We [...] assume that the ozone layer will gradually recover since the ban on ozone-depleting substances."

Fresh water consumption and aerosols are also not listed as planetary guard rails in the WBGU concept.

Web links

literature

Individual evidence

  1. a b c d e f g h i j k l m n o p q r s t u v w x y Will Steffen et al .: Planetary boundaries: Guiding human development on a changing planet . In: Science . tape 347 , no. 6223 , 2015, doi : 10.1126 / science.1259855 .
  2. Dieter Gerten, Hans Joachim Schellnhuber : Planetary limits, global development. In: Udo E. Simonis et al. (Ed.): Jahrbuch Ökologie 2016. Hirzel, 2015, pp. 11–19.
  3. Four out of nine “planetary limits” have already been exceeded. Press release, Potsdam Institute for Climate Impact Research, January 16, 2015.
  4. Christoph Streissler: Planetary limits - a useful concept? (PDF; 86 kB). Economy and Society, Volume 42 (2016), Issue 2, pp. 325–338.
  5. ^ Advisory Council for Environmental Issues (SRU): Environmental Report 2012. Responsibility in a limited world. (PDF; 6 MB). June 2012. p. 41 f.
  6. ^ Scientific Advisory Council of the Federal Government on Global Change (WBGU): Welt im Wandel. Social Contract for a Great Transformation. Main report 2011 (PDF; 5 MB). 2nd revised edition, ISBN 978-3-936191-38-7 , Berlin 2011, p. 66, accessed on January 19, 2020.
  7. Resources. Humanity drives nature beyond its limits. Der Spiegel from January 15, 2015.
  8. a b c d e f g h i j k l m n o Steffen, Rockström et al .: Planetary boundaries: Exploring the safe operating space for humanity . In: Ecology and Society . tape 14 , no. 2 , 2009 ( ecologyandsociety.org ).
  9. a b c Johan Rockström, Will Steffen, Kevin Noone, Åsa Persson, F. Stuart Chapin: A safe operating space for humanity . In: Nature . tape 461 , no. 7263 , September 2009, ISSN  0028-0836 , p. 472-475 , doi : 10.1038 / 461472a .
  10. Potsdam Institute for Climate Impact Research : Planetary Limits: A Safe Space for Mankind. Press release of September 23, 2009, accessed February 17, 2013.
  11. a b c Scientific Advisory Council of the Federal Government on Global Change (WBGU): Welt im Wandel. Social Contract for a Great Transformation. Main report 2011 (PDF; 5 MB). 2nd revised edition, ISBN 978-3-936191-38-7 , Berlin 2011, p. 34, accessed on January 19, 2020.
  12. Alessandro R. Demaio, Johan Rockström: Human and planetary health: towards a common language. (PDF; 420 kB). In: The Lancet. Volume 386, No. 10007 (2015), pp. 1917-2028.
  13. Joachim Radkau: The era of ecology. A world story. CH Beck, 2011, ISBN 978-3-4066-1902-1 .
  14. Federal Agency for Political Education : Economic Growth. Growth, Quantitative Growth, Qualitative Growth. Lexicon of Business, accessed on September 14, 2018.
  15. Herwig Büchele , Anton Pelinka (ed.): Qualitative economic growth - a challenge for the world. Innsbruck University Press, Innsbruck 2012, ISBN 978-3-902811-65-3 .
  16. ^ AC Newton, E. Cantarello: An Introduction to the Green Economy. Science, Systems and Sustainability . Taylor & Francis, 2014, ISBN 978-1-134-65452-9 .
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