Wasting class time?

Wasting class time?

Please get out your objectives #3-9 for a stamp.

Add new learnings as you compare your work with your neighbor’s.

Climate – on a geologic scale

First, try this:

Take the average of the following numbers: 100, 0

Take the average of 100,100,100,100,100,100,100,100,100,& 0

(that’s 9 sets of 100)

How does having more data affect an average?

2013 global average temperature

58.3 oF

Observations?

Three important inferences

Climate change is natural 100,000 year cycles between glacial

maximum (ice age) and interglacial periods (maximum warmth)

A change in -3oC (about -5oF) can create an ice age

*Historically, the RATE has been slow enough that species could evolve to keep up with the changes.

Milankovitch cycles create the 100,000 yr pattern Obliquity (Axial tilt) Eccentricity (orbit eliptical or circular) Precession (wobble on axis) Combination of these creates 100,000 year

cycle of warming and coolingEarth’s orbitaround the sun

CO2 levels

Where did CO2 come from thousands of years ago? Response of ocean to increased radiation: warm ocean

releases CO2

CO2 at beginning of Industrial revolution: 280 ppm Current CO2 levels: 396ppm

Where did this data come from?

Studying geologic climate

Historic records exist 150 years Inferred/Implied records Fossil records Tree rings – relative amounts of oxygen

isotopes (proxy methods) Ice cores - paleothermometers

Tree rings – isotopes of Oxygen

Ice core sampling

Check for understanding

Which is surprising to climatologists – that the climate changes or the current rate of change?

What is the name of the 100,000 year cycles of warming and cooling?

How do climatologists study the ancient atmosphere? (name 4 ways)

Why is a .7oC change significant?

Climate and civilization

Human civilizations change when climate changes

20,000 ybp (years before present) ice age: Bering strait freezes, people migrate to the Americas

8,000-7,000 ybp – warming period Mesopotamia flourishing, Jericho established

Mayan civilization – collapses suddenly 950 CE (common era – used to be called AD)Leif Erikson – 950 CE sails to Greenland

Black Death in Europe – famine 1315-1317 – needed to import grain from China

Little Ice age – 1550-1850Irish Potato Famine

Dust Bowl – 1930’s

Mild but persistent La Nina conditions coupled with changes of sea surface temperatures + poor farming practices

Wrap it up – discuss with your neighbor: Identify the evidence for and against

anthropogenic climate change.