Orbital-Scale Climate Change

Earth’s Orbit and Its Variations

Orbit and Insolation

How Does the Tilt Affect Climate?

Tilt Creates Seasons

How Does Orbit’s Shape Affect Climate

Perihelion and Aphelion

Seasons and the Elliptical Orbit

Seasonal Temperature Contrast

Tilt Change (Obliquity Variation)

Slide 11

Eccentricity of The Elliptical Orbit

Eccentricity Variations

Precession of Axis

Precession of Ellipse

Time Scales of Precession

Eccentricity and Seasonal Insolation

Tilt and Seasonal Insolation

Precession and Seasonal Insolation

Precession and Seasons

Impacts of Precession and Eccentricity on Insolation

Seasonal Insolation Changes

Insolation Control of Ice Sheets

Milankovitch Theory

Temperature and Ice Mass Balance

Seasons and the Size of Ice Sheet

Insolation Control of Ice Sheet Size

Three Factors that Control Ice Sheets

Insolation Control of Ice Sheet Size

Ice Sheet Lags Behind Summer Insolation Forcing

Delayed Bedrock Response Beneath Ice Sheets

Full Cycle of Ice Growth and Decay

Factors in Long-Term Evolution of Ice Sheets

Conceptual Phases of Ice Sheet Evolution

Evidence of Ice Sheet Evolution

Ice Sheet Changes Over the Last 150,000 Years

Insolation and Ice Volume

Orbital-Scale Changes in CO2 and CH4

Orbital-Scale Changes in CO2 and CH4

Trapping Gases in the Ice

Ice Core Drilling

Slide 42

Orbital-Scale Changes in Methane

Monsoon and Methane

Insolation Control of Monsoons

The Orbital Monsoon Hypothesis

How Did Monsoon Affect Methane?

Orbital-Scale Changes in CO2

Ice Sheet and CO2

The Basic Questions

Possibility 1: Physical Oceanographic Explanation of CO2 Changes

Possibility 2: Deep Ocean Reservoir

Ocean Carbon Pumping Hypothesis

Where Did the Pumping Occur?

How Glaciations Increased Productions at Low Latitudes?

How Glaciations Increased Productions Near Antarctica?

Changes in Ocean Chemistry

Changes in North Atlantic Deep Water

Changes in Circulation of Deep Water During Glaciations

Carbon System Controls on CO2 in the Glacial Atmosphere

The Mystery of the 100,000-Year Cycle

Why Have Ice Sheets Grown Larger Since 0.9 Myr Ago?

Slide 63

Why Have Ice Sheets Grown Larger Since 0.9 Myr Ago?

What Causes Abrupt Deglaciations?

Slide 66

Slide 67

Roles of Internal Climate Interactions