Possible Causes of Climate Change Plate Tectonics and Mountain Building

Theory of plate tectonicsRidge and subductionMountain interaction with airflow and ocean

currents Variation on the Earth’s Orbit

Milankovitch Theory○ Eccentricity○ Precession○ Obliquity

Possible Causes of Climate Change Plate Tectonics and Mountain Building

Theory of plate tectonicsRidge and subductionMountain interaction with airflow and ocean

currents Variation on the Earth’s Orbit

Milankovitch Theory○ Eccentricity○ Precession○ Obliquity

Eccentricity

Evolution of Earth’s eccentricity. Data taken from Berger and Loutre (1991)

Comparison of Antarctic temperature reconstructed from Vostok ice core deuterium measurements, with the Earth’s eccentricity cycle. Vostok temperature data was taken from Peteet et al. (1999)

Precession

Evolution of precession angle relative to the Northern Hemisphere Summer Solstice, and the associated July insolation at 65N. Data taken from Berger and Loutre (1991)

Obliquity

Evolution of the Earth’s obliquity. Data taken from Berger and Loutre (1991)

Evolution of Mars’ obliquity. Data taken from Laskar et al. (2004)

Possible Causes of Climate Change External Causes

Change in incoming radiationChange in composition of the atmosphereChange in Earth’s surface

Feedback MechanismsInfrared radiation (-)Snow-albedo feedback (+)Water vapor-greenhouse gas feedback (+?)Cloud feedback (+ or - ?)

What is feedback? Feedback describes the situation when output from an

event or phenomenon in the past will influence an occurrence or occurrences of the same event / phenomenon in the present or future.

Feedback is used in many applications, and here are a some examples:

1. Biology

2. Engineering

3. Computing systems

4. Social Sciences

5. Climate Science

Stefan-Boltzmann (Infrared Radiation) Feedback:

Negative

Snow Albedo Feedback Mechanism:

Positive

Water Vapor Feedback Mechanism:

Thought to be positive by climate models and most climatologists

Cloud Feedback Mechanism:

Sign of feedback basically unknown