Geology 102
Lecture 37 – Climate and Climate Change
1) What is the difference between weather and climate? And how does climate
change?
Weather is the daily status of the atmosphere.
_________ and __________ pressure zones in the atmosphere transfer heat across the
surface of the earth and is always in motion
Heat is provided to the earth through ________ __________________, excesses at the
equator are transferred to the poles by ocean and atmosphere circulation.
Climate is a record of the long-term trends in weather.
Atmospheric Circulation is driven by __________________ ______________ and
produces a Convection model - produces Meridional Circulation
Winds mover over land due to changes in albedo, insolation and thermal capacity.
Insolation – amount of sun reaching the planet, changes ______________ but is generally
constant over time. However, the amount of insolation has evolved over ___________
time. During Archean ~ 80-90% of present values, by PC-C boundary it was 94%.
Albedo – how much energy is reflected or radiated away from the earth.
Thermal capacity – the _______________ amount of energy that can be stored by fluids
and gasses.
a) with ice and low sea levels, ocean cools from the bottom up and has _________
thermal capacity.
b) With no ice and high sea levels, salty bottom waters, oceans warm from the
bottom up and has ___________ thermal capacity.
2) Milankovitch Orbital Parameters and their affect on climate
The shape of ___________ orbit around the _____________, and its orientation in this
orbit has greatly affected Earth’s climate throughout it’s history. Named for Serbian
mathematician who figured out the affects while in prison.
Eccentricty – change in shape of earth’s orbit (small variations from elliptical orbit).
Large deviations from the ______________________ orbit leads to high seasonality with
colder winters and warmer summers. Nearly elliptical orbits leads to lower seasonality
and more equitable climate. Variations in this orbital parameter change every
___________________ years.
Obliquity – change in the tilt of the earth within its orbit (varies from 21-24). This
parameter affects the distribution of heat between the hemispheres and changes ~ every
___________________ years.
Precession – change in the earth’s seasons that occurs every ________________ to
________________ years.
3) Ancient Climate Indicators
Coal – ________________________________ climate
____________ Sandstones – _________________________________ climate
Carbonates – ___________________________, warm climate, warm waters
Red Beds – ________________________ climate
Bauxites/Laterites – soils that formed in _____________________ climate
Evaporites – _____________ climate
_____________ Indicators: till, dropstones, glacial landforms, ____________ climate
4) Icehouse, Greenhouse and Transitional Climate Periods
Global Climate is subdivided into Icehouse, Greenhouse and Transitional Periods
Icehouse Periods are marked by __________________________; large, rapid _____
______________ _________________ (40-100 m); low atmospheric _________
contents
Transitional Periods are marked by intermediate to small ice caps;
___________________ _____ _________ __________________________ (10-40 m);
intermediate ________ content
__________________ Periods are marked by no permanent ice caps; ____________ sea
level fluctuations, ____________ atmospheric _______ content
Most of earth’s climate record is marked by greenhouse periods. Icehouse periods occur
at 2.2 Ga, 680-570 Ma (Snowball Earth), 440 Ma, 320-270 Ma, 45 Ma to current.
The initiation of the _______________-Antarctic current ~ 45 Ma ushered in our current
glacial period. Prior to this event global climate was warmer and more equable. This
glaciation intensified about 2 million years ago. Climate change during this period is
recorded in oxygen isotope records from deep sea sediment cores and ice cores on land.
During glacial periods the isotopically light oxygen is preferentially retained in the ice,
making the oceans “heavier”, whereas when there is no ice the oceans are “lighter”. Dust
and ice rafting events indicate global temperatures changed up to 2C in less than 10
years!!
Terrestrial Evidence for Pleistocene Glaciation
1. ____________________ and other glacial depositional features, also eolian
deposits
2. Changes in vegetation
3. Large Lakes
The glacial ice that covered North America was up to _____ miles thick at its maximum
and took more than _________________ years to melt. Large lakes also formed
throughout the western US and their remnants are all that is left.
5) Current and Future Climate
Anthropogenic input has likely changed climate. ______, _________, _________, and
SO4 all show rapid, abrupt increases in the last 1000 years. All of these increase surface
temperatures and are at their highest levels of the last ______________ years it is unclear
if this is out of their natural variation limits.
____________ is linked to climate change by increasing the greenhouse gases in the
atmosphere which hold in more heat. The CO2 levels recorded in the last 100 years are at
their highest level in the last 400,000 years and possibly the last 20-30 million years.
The temperature rise since the late 1800’s is unprecedented in the last 1000 years,
however, whether this is outside the realm of natural variaitions is unclear.
Models for global climate in the next 100 years indicate CO2 and SO2 emissions will
continue to rise, which may to lead to an increase in global temperatures of
_________C. This may be _______ as much as the natural variations during the last
______________ years. This amount of temperature increase may lead to a sea level rise
of _____________ m. Complete melting of the current ice sheets would raise sea level
_________________ m which would affect 2/3 of the world’s population. What will
(can) we do to stop (resist) climate change? Should we do anything?