March 30: Planetary Boundaries Flashcards
What is meant by planetary boundaries and how are they different from tipping points?
Planetary boundary: Concept that describes the environmental limits within which humans can operate safely and sustainably.
Tipping points are Earth system components that may exhibit large-scale, long term changes upon reaching critical global warming, greenhouse gas, or other thresholds.
What are the 9 planetary boundaries?
- Climate change
- Chemical pollution
- Stratospheric ozone depletion
- Atmospheric aerosol loading
- Ocean acidification
- Biochemical flows
- Freshwater use
- Land-system change
- Biodiversity integrity
What’s the status of (1.) climate change and what’s the problem associated with it?
yellow: in zone of incertainty (increasing risk)
Climate change can increase the water stress of a region. Reduce water availability, increasing evaporation rate.
Dramatic increase in atmospheric CO2 coincided with the Great Acceleration.
What’s the status of (2.) chemical pollution and what’s the problem associated with it?
Boundary not yet quantified
Chemical pollution can reduce the abundance of species and increase organisms’ vulnerability to other stresses. (like climate change).
The introduction of novel entities cause dramatic impacts on the stratospheric ozone layer.
Plastic are also novel entities. Accumulation of plastic is bad.
What’s the status of (3.) stratospheric ozone depletion and what’s the problem associated with it?
Green: below boundary (safe)
Antarctic ozone hole is expected to stay for several decades and the Arctic ozone hole may continue for the next decade or two. Dangerous because UV radiation comes from the sun and reaches the Earth, and that can cause cancer, health problems, it can harm crops and reduce ocean productivity.
Montreal Protocol: actions taken to avoid transgression of this boundary, ozone-depleting gases decreased.
What’s the status of (4.) atmospheric aerosol loading and what’s the problem associated with it?
Boundary not yet quantified.
Influence Earth’s radiation balance by scattering incoming radiation back to space and by influencing cloud reflectivity and persistence.
Air pollution is responsible for 800 000 deaths
Indoor smoke from solid fuels: 1.6 million deaths
Occupational airborne: 300 000 deaths
What’s the status of (5.) ocean acidification and what’s the problem associated with it?
Green: Below boundary (safe)
Elevated CO2 levels interfere with neurotransmitters in finfish, and they go towards predators.
Affect hearing of fish because of Otoliths.
Loss of marine organisms.
Loss of corals (which means loss of an habitat for many organisms)
What’s the status of (6.) biochemical flows and what’s the problem associated with it?
Red: Beyond zone of uncertainty (high risk)
Nitrogen and Phosphorus
Causing eutrophication, lead to the impairement of freshwater and coastal marine ecosystems around the world.
What’s the status of (7.) freshwater use and what’s the problem associated with it?
Green: Below boundary (safe)
Humans are altering river flow, spatial patterns and seasonal timing of vapor flows.
25% of river basins run dry before reaching the ocean (use of fresh water in the basins).
What’s the status of (8.) Land system change and what’s the problem associated with it?
Yellow: In zone of uncertainty (increasing risk)
Deforestation
Might turn the Amazon rainforest into a semi-arid savanna, because of conversion from rainforest to cultivated systems.
Land degradation, loss of irrigation water
What’s the status of (9.) Biosphere integrity and what’s the problem associated with it?
Genetic diversity: Red: Beyond zone of uncertainty (high risk)
Functional diversity: Boundary not yet quantified
rate of extinction of species is 100 to 1000 times more than natural.
What do the green, yellow and red zones represent on the planetary boundary diagram?
The green zone is the safe-operating space (below the boundary), yellow represents the zone of uncertainty (increasing risk), and red is the high-risk zone.
Where are we in relation to the proposed atmospheric carbon dioxide parts per millions concentrations boundary?
There is a dramatic increase in atmospheric CO2, that coincided with the Great Acceleration, but we’re still in the yellow zone for the climate change boundary, so we need to act, before it reaches the high risk zone.
What key human activities influence the boundary proposed for nitrogen?
The manufacture of fertilizer for food production
The cultivation of leguminous crops
Agriculture
Haber-Bosch method
What human activities influence the boundary proposed for ocean acidification? (see previous lectures)
From energy use.
Oil, gas, coal, biomass
Cars, deforestation, pipelines, using the internet, television, planes
