Planetary boundaries

State boundaries

Atmospheric aerosols, biosphere integrity, fresh water use, climate change, introduction of novel entities, biogeochemical flows, ozone depletion, land system change, ocean acidification

Status of climate change boundary

Crossed

Define core boundary

Crossing the planetary boundary would drive the earth into a new and unpredictable state with severe consequences for the biosphere

Define biodufel

A fuel made by a biological process such as anaerobic digestion rather than geological processes such as long term heat and compression that formed fossil fuels

outline what is meant by planetary boundaries

- 9 global processes regulate the stability of the land, atmosphere and sea

• Safe operating level for humanity/ a threshold value for a global process that is affected by human activity/ limits that global processes or systems must stay within + irreversible damage if exceeded

boundary status for biosphere integrity

crossed

boundary status for land system change

crossed

boundary status for biogeochemical flows

crossed

boundary status for stratospheric ozone

avoided

boundary status if ocean acidification

avoidable

boundary status of fresh water use

avoidable

boundary status for aerosols

not quantified

boundary status for introduction of novel entities

not quantified

outline the problems caused by crossing the climate change

- The Earth's temperature is largely controlled by greenhouse gases in the atmosphere.

- Evidence shows that periods of higher atmospheric carbon dioxide are correlated with higher average global temperature.

- Atmospheric temperature affects wind patterns, ocean currents, rainfall and other precipitation.

- Positive feedback occurs e.g. warmer seas melt polar ice; the sea is less reflective than ice so more heat is absorbed so the sea gets even warmer.

- Thermal expansion and melted ice running off land raise the average sea level. Without significant action, a rise of up to 7 m is predicted by 2100.

boundary for carbon dioxide

350ppm

wats to combat climate change

- international agreements

- Most people accept that the biofuel industry has a role in the reduction of fossil fuel combustion and that renewable resources should provide a greater proportion of the energy we use.

outline international agreements for climate change

Kyoto protocol, agreed by 84 countries in 1997, was the first of many major international agreements to address global warming. It set targets for reducing the greenhouse gases in the atmosphere. Some major polluters did not sign the agreement.

- The COP21 meeting in Paris in 2015, which, by April 2016 had been agreed by 174 countries, made further resolutions.

outline resolutions made in the Paris agreement

- Keep global temperatures 'well below' 2.0oC above pre-industrial times and 'to endeavour to limit' them to 1.5oC

- Limit greenhouse gas emission by human activity to what can be naturally absorbed, to start between 2050 and 2100

- Review each country's achievements every five years

- For rich countries to help poorer nations to adapt to climate change and switch to renewable energy.

state the core boundaries

- climate change

- biosphere integrity boundary

outline the route to biodiversity loss

- Habitat destruction has occurred in many ecosystems e.g. tundra, coral reefs, tropical rain forests.

- Populations of living organisms are reduced.

- If too few individuals in a species remain, the survival of the species may be under threat, and it may become extinct.

- Species interact so entire communities come under threat.

boundary of biosphere integrity boundary

10

ways to protect species

Monitor biodiversity

Species conservation e.g. seed banks, sperm banks

Prohibit international trade in endangered species and their products e.g. ivory

Limit fishing when fish are spawning

Limit logging

Limit the use of agricultural chemicals e.g. fertilisers, pesticides

Increase public awareness

problems with the land system change boundary

- Natural ecosystems, including rain forests, have been used for urban development, raising livestock and farming, including growing biofuel crops.

- Pollutants derived from agriculture and other human activities further degrade the remaining land.

- The production of biofuel crops and crops grown for export means that not enough food may be produced for local use.

how to deal with land system change

- No more than 15% of ice free land should be used for crop growing and human habitation.

- Farming should be concentrated in the most productive areas.

- People should eat less meat to reduce the area under cultivation.

- More efficient crop plants should be grown.

outline the biogeochemical flows

The balance of chemical elements maintained by natural cycles has been disrupted:

- Fertilisers use - atmospheric nitrogen is fixed in the Haber process and phosphorus is extracted from rocks.

- Agricultural nitrogen fixation

- Combustion of fossil fuels and biomass

consequences of biogeochemical flows

- Eutrophication from nitrate and phosphate run-off into bodies of water: algal blooms and anoxic zones are a direct threat to biodiversity.

- Acidification as excess carbon dioxide dissolves in seas, lakes and rivers: effects on aquatic organisms include the disruption of gas exchange in fish and the softening of the shells of Molluscs and exoskeletons of Arthropods.

outline the boundary of biogeochemical flows

No more than 62 million tonnes of nitrogen should be added to ecosystems each year, to prevent disruption of the global nitrogen cycle. Currently we add 150 million tonnes.

Boundaries are defined for other elements

e.g. phosphorus in the context of their biogeochemical cycles.

problems with the stratospheric ozone boundary

By 1970, the concentration of ozone in the stratosphere had decreased so much that in spring, a 'hole' in the ozone layer could be detected over Antarctica.

As ozone absorbs ultra-violet light, much more uv was penetrating the atmosphere than in the past.

Ultra-violet light generates mutations in DNA and cause damage to living organisms.

outline the Montreal protocols

By international agreement, the manufacture and use of chlorinated and brominated hydrocarbons, which are ozone-destroying, was to be phased out.

The stratospheric ozone boundary is the only one that has been avoided by deliberate action.

outline the problems with ocean acidification

Atmospheric carbon dioxide dissolves in bodies of water such as the oceans, and decreases their pH.

Before the advent of industry, the pH of the oceans was 8.16 but it is now about 8.03. This means that H+ ions are 30 times as concentrated.

effects of lowered pH of oceans

Absorbing excess H+ ions decreases the internal pH of phytoplankton. Their ability to perform enzyme-mediated reactions e.g. photosynthesis is compromised. So less oxygen is produced and less carbon dioxide is removed from the water.

Gas exchange in fish is less efficient.

Calcium leaches out of the calcium carbonate skeletons of corals, out of the shells of Molluscs and out of the exoskeletons of Arthropods. Even if the organisms survive this, they become more susceptible to predators.

outline the boundary of the ocean acidification

The boundary is defined in terms of the 'saturation ratio' of aragonite, a form of calcium carbonate. The saturation ratio describes how much aragonite is present in surface waters compared with a saturated solution.

Current levels are very close to the proposed boundary. Preventing a large increase in atmospheric carbon dioxide is likely to prevent this boundary being permanently crossed.

the fundamental problem of fresh water use

Only 2.5% of the water on Earth is fresh, and 61% of that is frozen.

Not all available fresh water is drinkable as it may contain toxic ions or dust.

Fresh water is not uniformly distributed around the world so some places have very little.

human activity that further reduces water availability

Increased use e.g. irrigating crops, daily life

Climate change

Pollution

Change in land use e.g. draining wetlands, deforestation

Increased human population and longer life spans

consequences of fresh water use

Desertification

Rives may fail to reach the sea

Fisheries are destroyed

The loss of bodies of water gives a wider area more extreme temperatures and makes it more arid e.g. following the drying of the Aral Sea.

how to avoid the fresh water boundary

We should limit the volume of water we take from rivers to 4000 km3 y-1.

Stop irrigating non-food crops e.g. biofuels

Use drip irrigation for food crops

Apply the 3Rs i.e. reduce, reuse, recycle

Use desalinated water

outline the problem of the atmospheric aerosol loading boundary

The atmosphere contains minute particles. Some are natural e.g. the ash from volcanoes, but others are put there by human activity.

Their effect depends upon their physical and chemical nature.

They are so varied that their effects have not been quantified, but they are estimated to cause 800 000 premature deaths each year.

examples of atmospheric aerosols

Soot absorbs heat and contributes to global warming.

Sulphates reflect heat and have a cooling effect.

Particles from diesel engines are inhaled and lodge in the lungs, increasing the risk of lung cancer, or, if small enough, pass into blood capillaries and increase the risk of cardio-vascular disease.

consequences of the atmospheric aerosols

The 'Asian Brown Cloud' over India comes from coal power stations, wood burning stoves and heavy industry. It blocks about 10% of the sunlight, lowering the temperature, evaporation rates and rainfall, disrupting the monsoon, increasing floods and droughts.

The extreme drought in the Sahel in the 1970s and1980s is linked to pollution from Europe and America reducing moisture in the air that moves over Africa.

Soot, especially from burning felled trees after deforestation, accumulates in the atmosphere, largely over the poles. It falls and darkens the ice sheets, which reflect less heat and melt more quickly.

boundary of atmospheric aerosols

The effects of atmospheric particulates are so variable that it is not currently possible to determine safe limits .

outline problems with the introduction of novel entities boundary

Novel entities may be persistent and have irreversible effects. They include:

synthetic organic pollutants e.g. DDT, PCBs

radioactive materials e.g. 131I, 32P, 14C, 90Sr

genetically modified organisms

nanomaterials i.e. particles with at least one dimension no bigger than 100 nm e.g. coatings on computer chips, self-cleaning textiles, antimicrobial silver nanoparticles in socks

micro-plastics e.g. plastic beads in cosmetics

outline useful novel entities

Nanoparticles: - thin films or surface coatings on computer chips

- self-cleaning textile surfaces

- protective insulating clothing

- antimicrobial silver nanoparticles in socks

- health and health care advances e.g. targeted methods drug delivery, new cancer therapies, early detection of diseases

Genetically modified organisms are recognised as being part of the solution to many problems e.g. those associated with world food shortages, drug manufacture, cleaning up pollution

outline the boundary of the introduction of novel entities

Some novel entities are already controlled e.g. the use of DDT is banned.

But of the estimated 100 000 manufactured chemicals and other entities, few have been properly assessed.

It is widely agreed that a defined boundary would be useful but it is not yet possible to establish one.