Lec 2 Flashcards
(28 cards)
Geologic time scale includes
Eons
Eras
Periods
Epochs
Ages(or series)
Eons (2)
Phanerozoic
Precambrian
Eras (3)
Cenozoic
Mesozoic
Paleozoic
Periods (4)
Quaternary (current)
Cretaceous
Jurassic
Triassic
Epochs (3)
Holocene
Pleistocene (ice age)
Paleocene
Epochs are divided into units called
Ages
Anthropocene
New epoch that we may have entered from the 18th century when global concentrations of CO2 and methane increased (Crutzen and Stoermer 2000)
Clear evidence that the Earth is beyond the Holocene epoch and now in the Anthropocene
Beyond the mid 20th century, there is very clear evidence for fundamental shifts in the state and functioning of the Earth beyond the limits of the Holocene.
Earth system and socio-economic trends show
Drastic increases in many factors in the mid 20th century
Evidence of change of epoch
Human population growth
Urbanization
Fossil fuel consumption
Biogeochemical changes(Carbon/nitrogen cycles)
Damage to the ozone layer
Coastal wetland loss
Fisheries collapse
Production of anthropogenic materials
Radiations
Mass extinctions
Climate change
Animal growth rate vs world population since 1970
Animal growth rate has decreased but overall world population is increasing drastically (due to human growth)
The greenhouse gases
CO2
Water vapor
Methane
Nitrous oxide
Ozone
Chlorofluorocarbons
Biogeochemical changes
Anthropogenic imbalance of the C cycle is superseded by that of the global N cycle
Biogeochemical changes- Nitrogen
Great amounts of nitrogen increase
Fossil fuel emissions release what types of stable isotopes for nitrogen
N-14
N-15 (greatly increasing)
Haber-Bosch Process
Artificial N fixation
Combines N gas and H gas using metal catalyst under high heat and pressure to form NH3, which is used as fertilizer
Forested wetland losses in coastal watersheds are attributed to
Upland land use
Fisheries collapsing
Large drop in fishery production from 1980
Production of anthropogenic materials
Great increase in aluminum, concrete, and plastics
Small increase in synthetic fibers
Radiation changes
Anthropocene can be from 1951 when plutonium was first found in soil after atomic weapons testing
Mass extinctions
Anthropocene could have started after 1950 when great mass extinctions were occurring
We are likely in a new mass extinction
How do we define the Anthropocene
Large change in geological conditions because of humans
Must be scientifically justified and a useful term
Can’t agree on a global stratigraphic marker for the beginning of the Anthropocene (spatially and temporally different opinions)
All agree that change is occurring, simply unsure how to categorize them
3 options for a formal stratigraphic definition in the GTS
The Anthropocene is a new epoch after the Holocene
Anthropocene is a new Epoch, replacing the Holocene
Anthropocene as a new Age/Stage within the Holocene Epoch
Proposed start dates
Ranges from 50k years ago to 1950
