EARTH 10 - Antarctica
Spring 2021
Lab 8:
Antarctica Paleoclimate
and CO2 records
General informa,on
• Course informa-on: see GauchoSpace materials
• Labs issued: ~Friday 11:59 pm.
• Lab due date: Friday 11:59 pm, the following week.
• Submit lab answers only via the designated quiz on GauchoSpace.
• Virtual office hours: see GauchoSpace course homepage
• Before star-ng the lab, you need to be up to speed on the corresponding lectures. Also
carefully read all the lab materials provided before you aKempt the ques-ons as many
answers are already in those materials. If you s-ll have ques-ons, then contact any TA.
Defini-ons
• Range= difference between the maximum and minimum value. You will need to
show the work on how you calculate these.
• Varia,on (for this lab)= the values of the maximum and minimum values over a
given period of -me.
• Ka= kilo annum, which is “thousands of years ago”.
• Example: 10ka is 10,000 years ago. A paleontologist found a fossil from 10ka.
A paleontologist found a fossil from 10,000 years ago.
• PPM= parts per million
• SST= sea surface temperature
• kyr= thousand years
Glacial Cycles
•
•
Glacia,on – glaciers forming as
temperatures get colder
Deglacia,on – glaciers mel-ng
as temperatures get warmer
•
•
•
This process transi-ons the planet
from full glacial condi-ons to
warm interglacial periods
characterized by less con-nental
ice and changes in sea level
A glacial cycle - Glacial à
interglacial à glacial
•
Aka peak ice back to peak ice
Or interglacial cycle - interglacial
à glacial à interglacial
•
One interglacial cycle
minimum ice back to minimum ice
One glacial cycle
What controls climate?
Short term controls (less 1 Ma):
• Solar Energy varia-ons (Milankovitch cycles)
• Greenhouse gas concentra-ons control how much heat can leave Earth’s atmosphere. Without
greenhouse gases the planet would be frigid.
Long term controls (greater than 1 Ma):
• Plate tectonic processes
Earth’s present ice age:
Earth is presently in the midst of an interglacial period within an ice age. A glacial period
corresponds to maximum ice cover, such as during the Pleistocene.
Ice Age: interval of geologic -me in which the world has significant ice cover (essen-ally, any ice
sheets in the world)
Milankovitch Cycles
Incoming radia-on periodically changes with:
1. Eccentricity of Earth’s orbit - 100,000 year cycle
2. Tilt of Earth’s axis - 41,000 year cycle
3. Precession of Earth’s axis - direc-on is -lted (wobble of
Earth’s axis), 23,000 year cycle
These varia-ons are caused by the gravita-onal pull of the sun
and the other planets. Although complicated, they are fairly
predictable if all of the necessary parameters are included.
LGM, Glacial Maximums, glacia-ons, deglacia-ons
• LGM= Last glacial maximum ~20ka
• Glacia-ons= temperatures are geeng colder through -me
• Deglacia-on= temperatures are geeng warmer through -me
Earth has undergone glacial and interglacial
periods. This episodic nature is primarily caused
by cyclical changes in the Earth’s eccentricity,
axial ,lt, and precession, which cause varia-ons
in the amount of solar radia-on reaching Earth,
impac-ng the advance and retreat of Earth's
glaciers.
Think of precession similar to the axis of the
Earth behaving as a top as it begins to falter ager
being spun.
Greenhouse effect Refresher
CO2 and other greenhouse gases interrupt the return
of heat as long wave radia-on heading out to space.
The CO2 absorbs the radia-on and emits it in all
direc-ons… some out to space, but much of it back
to Earth.
Fossil Fuels:
The vast majority of the CO2 that has been added to
the atmosphere has come from burning fossil fuels.
Fossil fuels are used to generate electricity,
temperature control (AC and heat), industry, and
transporta-on.
Tips…
• Ensure your units are what the ques-on is asking for
• Keep in mind there is a correct and incorrect direc-on to read the graph. Leg to
right or right to leg. Think of which way -me is moving and keep the order of
events in that logical order.
• Pay aKen-on to the x-axis scales in figure 1: some may increase going ’up’ on the
graph and some may decrease
• Rate calcula,ons:
Magnitude of change measured/-me period it took for change to occur =
rate of change per unit of measurement.
• For this lab it will be per 1,000 years or per 1 year, be mindful of what the
ques-on is asking.