planetary boundaries

Question 1

define planetary boundaries

Answer 1

safe operating space for humanity

once human activity has passed certain thresholds (planetary boundaries), there is a risk of ‘irreversible and abrupt environmental change

Question 2

how many planetary boundaries are there?

Answer 2

nine

Question 3

which planetary boundaries have been crossed?

Answer 3

biodiversity
climate change
nitrogen
land use

Question 4

which planetary boundaries are avoidable?

Answer 4

fresh water
ocean acidification
ozone boundary

Question 5

which planetary boundaries are unquantified?

Answer 5

chemical pollution
aerosol boundary

Question 6

biodiversity - planetary boundary

Answer 6

human activity –> environmental changes too fast for natural selection to produce organisms that adapt to changes and many species have become extinct

changes in habitat –> reduction in biodiversity in regions like tundra (increase in temperature) and marine environments (pollution with oil, acid and sewage)

coral reef bleaching and costal plain submersion –> rising sea levels, reducing biodiversity

Question 7

climate change - planetary boundary

Answer 7

greenhouse gases are continually being added to the atmosphere

causing an increase in global temperature, climate change, rise in sea levels

Question 8

nitrogen - planetary boundary

Answer 8

denitrification due to waterlogged soils

use of agricultural fertilisers leading to eutrophication

Question 9

land use - planetary boundary

Answer 9

deforestation –> farming and urban development has led to a conflict between the need to grow food and the need to grow biofuels and protect natural habitats

Question 10

fresh water - planetary boundary

Answer 10

organisms need fresh water to live

crossed if do not have enough fresh water to survive

2.5% of water is still fresh

important as it only contains a low concentration of dissolved salts

decrease in supply of freshwater is due to changing landscapes, agriculture, increased demand from humans, water pollution and climate change

Question 11

ocean acidification - planetary boundary

Answer 11

pH of the oceans is decreasing –> dissolving carbon dioxide forming carbonic acid –> releasing hydrogen ions

low pH –> mollusc, coral shells and arthropod exoskeletons softening, making them vulnerable

gill structure in fish is also affected by low pH and their functioning is damaged

Question 12

ozone - planetary boundary

Answer 12

chloro-fluorocarbons (CFCs) favour the breakdown of the ozone

CFCs were widely used in spray cans, solvents, refrigerator coolants and manufacture of food and drink containers

resulted in the thinning and development of a ‘hole’ in the ozone layer

use of CFCs in spray cans was banned in 1978

ozone layer is now recovering naturally

Question 13

chemical pollution - planetary boundary

Answer 13

organic pollutants, radioactive materials, nanomaterials and micro-plastics

could all interact with each other and produce harmful effects

variable we cannot suggest a boundary

Question 14

aerosol - planetary boundary

Answer 14

atmospheric aerosols are the microscopic particles put into the atmosphere by combustion of fuels and by creating dust from digging and quarrying

sulphates in aerosols reflect sunlight, providing a cooling effect, but other particulates reradiate it, increasing warming

can lead to respiratory problems and cause death from lung disease

Question 15

what can we do to help biodiversity - planetary boundary

Answer 15

monitoring biodiversity
collecting materials for gene banks
raising public awareness
reduce human behaviour that has generated biodiversity loss

Question 16

what can we do to reduce climate change - planetary boundary

Answer 16

production of biofuels – these fuels are made by biological processes

growth of biofuel crops takes in carbon dioxide from the atmosphere, the release of carbon dioxide when they’re burnt has less impact – carbon neutral

biofuels can be made by anaerobic digestion of plant material

Question 17

what can we do to help nitrogen - planetary boundary

Answer 17

planting fields of legumes to increase nitrogen fixation

ploughing soil to improve aeration

prevent anaerobic conditions

Question 18

what can we do to help land use - planetary boundary

Answer 18

changing farming practices to concentrate it in the most productive areas

reducing consumption of meat would reduce land being cultivated

Question 19

what can we do to help fresh water - planetary boundary

Answer 19

water conservation (not irrigating non-food crops)

water efficiency

waste water reclamation

drip irrigation systems

desalination is an important technology that removes minerals from salt water to produce fresh water

Question 20

what can we do to help ocean acidification - planetary boundary

Answer 20

reduction in the burning of fossil fuels