THERMOHALINE CIRCULATION:THE GREAT OCEANIC CONVEYOR BELT

The Movie Story

NOT CORRECT!

Air is pulled down in a high pressure system This causes warming and nice weather!

The Complexity of Global Climate Change

1. Introduction to the Greenhouse Effect On Earth On Other planets

2. Global Warming Today? We need a record for comparison

3. Earth has a History of Climate Change Measuring climate change

in Earth’s geologic past. Climate cycles in Earth’s past.

4. Scientific Uncertainty What’s Fact What’s Probable What’s Uncertain

5. Global Warming Today! Why should we care? Possible effects.

GLOBAL WARMING

1. Introduction to the Greenhouse Effecta. Greenhouse Gases – CO2, Water Vapor, etc.b. Absorption of long wave radiationc. Effects on Earthd. Effects on other planets – Venus and Mars

VENUS

MARS

EARTH

Isotope Atomic Mass Abundance

16O 15.99491463 99.7587% 17O 16.9991312 0.0374% 18O 17.9991603 0.2039%

How can we examine past climate?

Hydrogen Deuterium Tritium0 neutrons 1 neutrons 2 neutrons

Isotopes – Varieties of an element that contain different #’s of neutrons

Oxygen has several isotopes

Seawater (H2O)has oxygen in it.

Evaporationfrom oceans

Polar Ice is 30 p/milEnriched in 16O

2. Earth has a History of Climate Change

Measuring climate change in Earth’s geologic past.

Microfossil shells preserve ancient δO18 from seawater. A record of past temperature

Coccolith Foraminifera

2. Earth has a History of Climate Change Measuring climate change

in Earth’s geologic past. Paleothermometry with Oxygen Isotopes Oxygen Isotopes – O16, O17, O18

Ratio in Water Controlled bya. Temperatureb. Phase Change (e.g., liquid to

gas)

δO18 ~ O18/ O16

Cold Climate: δO18 in ocean

Warm Climate: δO18 in ocean

2. Earth has a History of Climate Change

The δO18 Record

Other Sources of Climate Dataa. Ice Cores

Other Sources of Climate Datab. Pollen

Other Sources of Climate Datac. Historical Records

Winter Landscape by Peter Brueghel, 1601The Little Ice Age in Holland

2. Earth has a History of Climate Change Climate cycles in Earth’s past. 1st Order – Hot House/Ice House:Millions of years

2. Earth has a History of Climate Change Climate cycles in Earth’s past. 2nd Order – Glacial/Interglacial:Thousands of years

The Pleistocene Epoch:1.8 million to 10,000 years ago

A Much Different World

North America During the Pleistocene

What If Today’s Glaciers Melted?

2. Earth has a History of Climate Change Climate cycles in Earth’s past. 3rd Order – Years To Hundreds of Years: The Historical Record

2. Earth has a History of Climate ChangeWhy are there climate cycles? Hypotheses - a. First Order: Changes in Greenhouse

Effect from Plate Tectonics b. Second Order: Changes in amount

and distribution of incoming solar radiation - Milankovitch Cycles

c. Third Order – Sunspots, Volcanism, Other??

3. Global Warming Today? Evidence for and against. Atmospheric Rise in CO2

GLOBAL TEMPERATURES?

4. Scientific Uncertainty What’s Fact

a. The Greenhouse Effect is real and has operated throughout Earth history.b. Atmospheric concentrations of

CO2 are increasing due to human activity.

What’s Probablea. 1 – 3o C Temp rise by 2150b. Sea-level rise of 10 –30 cm

What’s Uncertaina. Effects on ocean/atmosphere circulationb. Weather Patternsc. Effects on Agricultured. Runaway Greenhouse Effect?