Lecture 1: Anthropocene Flashcards
Anthropocene=
a proposed epoch dating from the start of significant human impact on Earth’s geology & ecosystems
geologic time = ____ time
what is the geological time scale? (GTS) List in order
deep
Eons
Eras
Periods
Epochs
Ages (subunits of epochs)
How old is the Earth? (aprox)
4.6 billion years old
___ are the largest time unit in the GTS
____ are the smallest time unit in the GTS
eons
ages
where are we now in the GTS?
eon: phanerozoic
era: Cenozoic
period: quaternary
epoch: holocene
Why is it hard to define a new epoch right now?
Defining a period while in it has never been done before- this is problematic
list a few reasons that support that we’ve entered a new epoch
- human pop growth rate explosion
- inc urbanization
- mass extinctions
- climate change
- damage to ozone layer
- anthropogenic materials (plastic, concrete)
- coastal wetland loss
When did the Anthropocene start?
This is not solved yet!
Some proposed start dates are:
- some dates pre-industrial revolution
- 1760: industrial revolution
- 1945: nuclear weapon denotation
- 1950s: Beginning of the great acceleration; persistent industrial chemicals, plutonium from atomic weapon testing found in soil in 1951 could mark the Anthropocene
What’s a recent alternative to adding the Anthropocene as an epoch?
Anthropocene as an ongoing event, not an epoch
geological event= major transformative episode in Earth’s history that varied spatially and and temporally (they are very important and change our planet)
Who proposed the Anthropocene and made it popular? When?
Biologist Eugene Stoermer and Chemist Paul Crutzen
(in the Global Change Newsletter)
Year published= 2000
Pleistocene epoch=
ice age
When did Paul Crutzen suggest that the Anthropocene started?
In the late 18th century, when analysis of air trapped in polar ice showed the beginning of growing global concentrations of CO2 and methane
In 1873, Italian geologist Antonio Stoppani suggested we were entering an:
Antropozoic era
T/F
our socioeconomical trends show logarithmic growth of almost everything (population, urbanization, water use, paper production, fertilizer consumption, tourism)
False
These all show exponential growth :(
What do graphs show about our earth system trends?
eg.
- surface temp
- atmospheric CO2 and methane
- tropical forest loss
- domesticated land
these are all growing exponentially
T/F
urbanization is growing at a similar rate all around the world
true
people everywhere are moving to the cities for jobs
What are some changes that are happening with Carbon?
overall levels of CO2 and CH4 are increasing; there are lots of fluctuations- not following trajectories of the past
What are the 6 most important greenhouse gases? List them in order of potency, not abundance
- CO2 (most abundant, least potent)
- water vapor
- methane (21x as potent as CO2)
- N2O (laughing gas): 310 CO2
- tropospheric ozone: 1000 CO2
- CFCs: 4750 CO2
___ are responsible for breaking down the ozone layer
CFCs (chloroflourocarbons)
the layers inside ice cores indicate ____
The bubbles=
larger chunks=
seasons (summer= light, winter= dark)
bubbles= gasses from the atmosphere at a certain time
larger chunks= sediments
T/F
the anthropogenic imbalance of the C cycle is superseded by that of the global N cycle
true!
Anthropogenic flux for C= +13%
Anthropogenic flux for N= +108%? (much more of a change)
nitrogen leaves a clear trace in the geological record. Describe trends of soil nitrogen (nitrate NO3) N15, and N14
soil N (NO3)= doubled in the past century b/c of fertilizer
N15 is retained in animal tissued: decrease in N15= increase in N14 (more anthropogenic emissions)
What are 2 reasons causing N14 to increase?
- Fossil fuel emissions: NOx (nitric acid etc) emitted into the atmosphere
- The Haber- Bosch Process
- Artificial N fixation
Describe the Haber-Bosch Process
this is artificial nitrogen fixation. It combines N gas and H gas using a metal catalyst under high heat and pressure to form NH3
NH3 gets into the N cycle b/c animals in the soil immobilize it, then die and break down
___ is the main source of anthropogenic nitrogen fixation
fertilizer production (Haber Bosch process)
What could be one of the causes of the more powerful/ frequent storms we have been experiencing recently?
anomalies in temp of ocean surface
What is the Montreal Protocol?
the banning of CFCs to decrease damage to our ozone layer
- it is helping
____ ___ provide habitat, water purification, etc, and they are being destroyed by urbanization and global warming.
coastal wetlands
The collapse of fisheries is connected to the loss of ___
wetlands
also overfishing is out of control!
What has been appearing in our oceans/ sediments?
anthropogenic materials
- aluminum
- concrete
- plastics
- synthetic fibers
Explain the spikes in radioactive materials in the 1960s
these spikes were not natural; used for fuel of atomic weapons
the huge spike in 1964= date of atomic bomb testing
this increase in radioactive materials is evidence of anthropogenic change
How do we define the Anthropocene?
= profound change in geological conditions and processes due to humans
- must be scientifically justified
- can’t agree: on a spatial and temporal marker for the onset of the Anthropocene
- agree: changes are occurring- just don’t know how to categorize it
what are 3 alternatives for the Anthropocene?
- Add the Anthropocene as a new epoch after the Holocene
- Replace the epoch Holocene with Anthropocene (not popular)- downgrade holocene to age
- the anthropocene as a new age/ stage within Holocene epoch
*know what these look like on the GTS scale
Summary of proposed start dates/ events for the Anthropocene (9)
- Megafauna extinction- 50,000- 10,000 yr BP
- Origin of farming- 11,000 yr BP
- Extensive farming- 8,000yr BP to present
- Rice production- 6500yr BP to present
- anthropogenic soils- 3000-500ys BP
- New-Old world collision- 1492-1800
- industrial revolution- 1760- present
- Nuclear weapon denotation- 1945- present
- persistent industrial chemicals- 1950 to present
what was the proposed formal definition of the Anthropocene in 2017 by the “working group on the Anthropocene”?
Anthropocene as a new epoch
- starting mid 20th century (~1945- plutonium fallout)
In ___ Gibbard et al. proposed that the anthropocene is:
2022
an ongoing event, not an epoch
- this is informal, but still a geological definition (but does not appear in the GTS)
geological event=
major transformative episode in earth history that vary spatially and temporally
- very important; they change our planet
- Gibbard et al. suggested that the anthropocene is an ongoing geological event
give 2 examples of ongoing geological events
- great oxidation event (an increase of oxygen in atmosphere 2.4-2.0 Ga)
- forestation of continents in the middle-late Devonian
(land was colonized by plants- very important, but didn’t happen at the same time everywhere)
