1 - Anthropocene Flashcards
Etymology of the word anthropocene
Greek ‘anthropos’ = human being, mankind
-cene = word-forming element in geology, from latinized form of greek kainos “new”
What is deep time? How is it measured?
= geologic time
Geologic Time Scale (GTS):
eons->eras->periods->epochs->ages
What are the eons?
Only two:
Phanerozoic (current)
Precambrian
Name the eras
Cenozoic (current)
Mesozoic
Paleozoic
Current period? Commonly known periods?
Current = quaternary
Cretaceous, jurassic, triassic
What was the ice age epoch? Current epoch?
Ice age = pleistocene
Current = holocene
Epochs are also divided into subunits called
Ages
When did the holocene start?
11.7k years ago
Where are we now? (Eon, era, period and epoch)
Eon = phanerozoic
Era = cenozoic
Period = quaternary
Epoch = holocene
What makes the anthropocene unique compared to other geological units?
Trying to define a geological event as it is happening
Support towards the idea that we have entered a new epoch with the anthropocene (11)
- human population growth explosion
- increased urbanization
- fossil fuel consumption
- biogeochemical changes
- mass extinctions
- climate change
- damage to ozone layer
- coastal wetland loss
- fisheries collapse
- anthropogenic materials
- radiogenic fallout
What is the great acceleration?
After WW2, economic activity of the human enterprise continues to grow at a rapid rate, clear evidence for fundamental shifts in the state and functioning of the Earth system that are driven by human activities
Nuclear testing, radioactive materials, increasing population, increased N in soils…
Socio-economic increases since the great acceleration
Energy use, fertilizer consumption, water use, paper production, urban population…
Earth system trends since the great acceleration
Increasing carbon dioxide, methane, % loss of stratospheric ozone, surface temperature, tropical forest loss, marine fish capture
What happened to human population growth in 1950 (great acceleration?)
Annual growth rate of the world population was spiking, peaked at 2.1%
Name the greenhouse gases
- carbon dioxide (main focus bc remains in atmosphere longer)
- water vapor
- methane
- nitrous oxide (N2O)
- Ozone (O3)
- chlorofluorocarbons (CFCs)
last four: smaller amount can cause greater impact on global warming
How is there biogeochemical change with regard to the carbon cycle? briefly describe the cycle
There is an anthropogenic flux in the amount of carbon available for the cycle since the 1950s
Sources preserve carbon, during the cycle it moves from one reservoir to another and is available for certain processes (e.g. forest fire -> released into the atmosphere -> absorbed into ocean -> decreased pH)
Biogeochemical changes that are evidence of the anthropocene
Imbalances in the carbon and nitrogen cycles
Changes in biogeochemical cycle of nitrogen
Two main nitrogen isotopes are nitrogen 14 and 15
Nitrogen 15 is found in animal tissues
Nitrogen 14 is found in fertilizers and is increasing
What is the Haber-Bosch Process? provides evidence of…
Artificial N fixation. Combines N gas and H gas using a metal catalyst under high heat and pressure to form NH3 (ammonia), which is used as fertilizer
Evidence of biogeochemical change in N cycle = anthropocene
Explain the damage to the ozone layer
“Good” ozone that protects us from UV radiation
A hole in the ozone was discovered around arctic, caused by chemicals called CFCs
Ozone is now recovering
Why are coastal wetlands being lost? Main causes?
Big cities around coastal areas lead to modification of the landscapes
- Silviculture
- Development
- Agriculture
Why did the fisheries collapse
In a lot of areas, there is no regulations on how much fish you can take.
Over 200 nautical miles offshore, you are no longer fishing in Canada so there are no regulations
Production of anthropogenic materials as evidence of the anthropocene
Production of plastics, synthetic materials, concrete, aluminum
Anthropogenic materials have entered the food chain
Why are mass extinctions considered evidence of the anthropocene?
There is an increase in lost species
Extinctions have happened throughout geological history, but more are going extinct than is normal
What are background extinctions?
Natural ‘background extinctions’ occur periodically at a background rate
e.g. 10% species lost/1 MY; 30% species lost /10MY
What are mass extinctions?
Higher extinction rates than normal (over shorter time)
Higher magnitude (% species lost) and rate (how quickly)
e.g. 75% of species in a short time period (2 million years)
How do we define the anthropocene?
- profound change in geological conditions and processes due to humans
- must be scientifically justified, and useful term for the scientific community
- can’t agree on a global stratigraphic marker for the onset of the anthropocene, but all agree that changes are occuring
What are the three options for a formal stratigraphic definition of anthropocene in the GTS
- The anthropocene as a new Epoch, following the Holocene
- The Anthropocene as a new Epoch, replacing the Holocene (that would be downgraded to terminal age/stage of the pleistocene epoch)
- the Anthropocene as a new age/stage within the Holocene epoch
Examples of proposed start dates for the anthropocene
- Origin of farming ~11000 BP
- Extensive farming ~8000 BP
- Industrial revolution 1760 to present
- Nuclear weapon detonation 1945 to present
Slide 66
What start point was suggested in 2017 by the “Working group on the anthropocene”
Use the plutonium fallout in the mid 20th century as a start point (can be measured)
Recent alternatives to the anthropocene classification (rather than as an epoch)
Anthropocene as an ongoing event
- informal but still a geological definition (not stratigraphic = not appearing in GTS)
Describe geological events
- tend to span for several million years and don’t happen at the same time everywhere
- better reflects the reality of historical and ongoing human-environment interactions and their spatial and temporal differences
- geological events are major transformative episodes in the earths history that varied spatially and temporally
