Lecture 2 - Anthropocene

Question 1

Formal definition of Anthropocene

Answer 1

3 options for a formal stratigraphic definition in the GTS:
1) The Anthropocene as a new Epoch, following the Holocene
2) The Anthropocene as a new Epoch, replacing the Holocene
3) The Anthropocene as a new Age/Stage within the Holocene Epoch

Question 2

Debate about the Anthropocene

Answer 2

Idea of the Anthropocene: asking if we have entered a new epoch
- Can’t agree on a global stratigraphic marker for the onset of the Anthropocene; agree changes are occurring, unsure how to categorize

Question 3

Who introduced the term Anthropocene in scientific literature and when

Answer 3

Paul J. Crutzen and Eugene F. Stoermer (2000)

Question 4

What the evidence of change that supports the idea of the Anthropocene are, and why this is important

Answer 4

1. Human population growth rate explosion
2. Increased urbanization
3. Fossil fuel consumption
4. Biogeochemical changes
   - anthropogenic imbalance of the C cycle is superseded by that of the global N cycle; due to fossil fuel emissions and the Haber-Bosch process (artificial N fixation for the production of fertilizers)
5. Mass extinctions
6. Climate change
7. Damage to ozone layer banned the use of chlorofluorocarbons in several countries and since then we’ve been doing better
   - Montreal Protocol
8. Coastal wetland loss
   - Due to: silviculture > development > other uplands > agriculture
9. Fisheries collapse
   - Related to coastal wetland loss
10. Anthropogenic materials
    - Aluminum, concrete, plastics, synthetic fibers
11. Radiogenic fallout

Question 5

What are the potential start dates for the new geologic unit that are being considered

Answer 5

1. Megafauna extinction
   - 50,000-10,000 yr BP
2. Origin of farming
   - ~ 11,000 yr BP
3. Extensive farming
   - ~8,000 yr BP to present
4. Rice production
   - 6,500 yr BP to present
5. Anthropogenic soils
   - ~3,000-500 yr BP
6. New-Old World collision
   - 1492-1800
7. Industrial Revolution
   - 1760 to present
8. Nuclear weapon detonation
   - 1945 to present
9. Persistent industrial chemicals
   - ~1950 to present

Question 6

Where are we now in the GTS?

Answer 6

Geologic time scale:
Eons
Eras
Periods
Epochs
Ages

Where we are now:
Eon: Phanerozoic
Era: Cenozoic
Period: Quaternary
Epoch: Holocene

Question 7

Is the debate among scientists over?
- Informal definition of the Anthropocene

Answer 7

No! The debate is whether to describe it in terms of Geologic Time Scale. Can’t agree on a global stratigraphic marker but all agree that changes are occurring, simply unsure how to categorize them. Some still think that the term ‘Anthropocene’ is best used informally.

Recent alternative: Anthropocene as an ongoing Event, not an epoch
- informal but still a geological definition (though not appearing in the GTS)
- comparable to other significant events, informally marked in the Earth’s geological record (events span for millions of yrs but don’t happen at the same time everywhere)

Question 8

What are the 6 GHGs?

Answer 8

1. CO2
2. Water vapor
3. Methane
4. Nitrous Oxide
5. Ozone
6. Chlorofluorocarbons