Main dimensions and their tipping points

Following the climate conference held in Copenhagen, the scientifi c team organised by the Stockholm Resilience Centre in Sweden published a study in Nature magazine which affected professionals‘ thinking at least as much as The Limits to Growth did when published in 1972. The authors claim that in three out of 8+2 dimensions³ humanity has already overstepped the lim-its of a safe existence. The main limlim-its that have been crossed involve the emissions of the greenhouse gases that cause climate change, increases in nitrogen fl ows due to fertilisation and concentrated animal farming, and the radical decrease in biodiversity.

3 1. climatic change, acidifi cation of the oceans, 3. the thinning of stratospheric ozone, 4. the nitrogen cycle, 5. the phosphorus cycle, 6. global fresh water consumption, 7.

changes in land use, 8. changes in biodiversity, 9. changes in the aerosol content of the atmosphere, 10. chemical pollution

Figure 3-1. Planetary Boundaries (Rockström, 2009)

Fig. 3-2. Planetary Boundaries II (Steffen et al., 2015)

The authors of the study felt certain enough in eight areas to be able to defi ne critical limits and state how far mankind is from the so-called tipping points.

Regarding chemicals and atmospheric particles, the analysis was postponed.

As far as the climate goes, we know that the carbon dioxide concentration in the air was 280 ppm in the Holocene, which created ideal conditions for hu-man evolution over the past fourteen thousand years. The ‘critical concentra-tion’ is somewhat higher than this; some professionals suggest it lies around

400 ppm. As indicated by the fi gure below, scientists think that until the criti-cal point is reached, changes can be prevented, and Earth will be capable of compensating by fl exibly adapting. Beyond the limits, effects are irreversible.

Planetary

Boundary Threshold

Control variable (e.g., ppm CO₂)

Responsce variable (e.g., extent of Land ice)

Safe operating

space

Zone of uncertainty

Figure 3-3. Planetary boundaries III (Rockström, 2009)

GEO-5, the latest global assessment report of the UN‘s Environmental Pro-gramme, also mentions the limits of planet Earth. Of course, scientists only agree that such limits exist, but opinions as to where these limits are tend to be very di-verse. Our knowledge is insuffi cient, the context is extremely complex, and thresh-olds will probably only allow more precise defi nitions to be created later on. Some limits have been overstepped with no spectacular results, while changes at the global scale may occur without ever overstepping a single threshold. Spectacular changes like the melting of the polar ice caps or the retreat of glaciers can occur, while there are less spectacular ones like decreases in biodiversity. Overstepping the thresholds occasionally results in global effects such as damage to the ozone layer; other cases only have local effects such as pollution caused by nitrogen compounds. However, sudden changes (‘tipping over’) are well known in ecology.

Conditions that cause rapid fi sh mortality may arise overnight, or even on a shorter timescale as the combined impact of a number of ecological factors. This can be true of larger systems, which is what is really dangerous. The mixing of local and global dimensions of issues may also cause problems. Nitrogen overdoses may cause local problems in China, while Africa may welcome the increased use of fertilisers for fi ghting famine. Many scientists claim that human interventions into the functioning of Earth have by now become so signifi cant that the Holocene is already over and has been replaced by the so-called Anthropocene – a time when the future of the planet is fundamentally infl uenced by human activity.

‘The history of life on Earth – as Rachel Carson says – has been a history of interaction between living things and their surroundings. To a large extent, the physical form and the habits of earth‘s vegetation and animal life has been molded by the environment. Considering the whole span of earthly time, the opposite effect, in which life actually modifi es its surroundings, has been rela-tively slight. Only within the moment of time represented by the present cen-tury has one species – man – acquired signifi cant power to alter the nature of his world.’ (Carson, 1962, Chapter 2)

In ecology, the ‘carrying capacity’ of a given territory is considered to be the largest possible population with a long-term survival ability that does not cause harm to the given territory. We may raise the theoretical question how many people the Earth can accommodate at an acceptable or preferred level.

The calculation is complex because we have no knowledge about:

• the resources future generations will use, or,

• the course of development developing countries will take.

The best possible and the worst possible scenario may be very different.

Historical experience proves that optimists may have grounds for their beliefs:

they claim that individuals make discoveries, so if enough individuals think about the solution to a problem they will be able to fi nd one (Julian Simon). The recent change in the dimensions of the problems, however, counters the more optimistic perspectives. So far the economy has been dwarfed by the size of the biosphere, but it is now becoming dominant.

Supporters of the optimistic approach claim that today‘s generation may leave less natural resources for generations to come, but that our successors will have a higher standard of technology and a larger amount of capital (Vorosmarty, 1991) .

Regarding the future of the Earth, it is crucial how limited the planet‘s carrying capacity is, and how much the limits of carrying capacity are resistant to erosion.

Carrying capacity, ~ of a landscape, ~ of environment: 1. The possible rate of complex exploitation (living, production, recreation) of the landscape in a given territory that expresses the largest possible number of population it is able to accommodate for the purpose of living and manifold social activ-ity. The ~ of a landscape may be examined separately by the basic forms of activities with the consideration of how ~ is limited or intensifi ed by the rest of the activities. – 2. Ecological strategies. – 3. A central category of ecological economy. Its meaning is identical to sustainability, only it refers directly to ecosystems (unlike the previous term which is an indicator of human activity. (Láng, 2002)