L1: Quaternary glaciations to global warming

What has Quaternary climate been like and where does much of the data for this period originate from?

• Dominated by long, cold, glacial cycles interleaved with short, warm inter-glacials.

• Much of this data comes from proxy data and oxygen isotopes.

How has anthropogenic activity influenced Quaternary climate?

Estimated that human activity has delayed the next cold glacial period by 500,000 - 600,000 years.

How do IPCC projections suggest that Quaternary climate is changing?

Suggest that we could be approaching a hothouse/warmhouse phase similar to that of the Paleocene and Eocene.

What are two major drivers of climate change?

• Forcing mechanisms → mechanisms that cause a system to deviate from its equilibrium state (external or internal).

• Feedbacks → amplify or stabilise the climate system (positive or negative).

Why did the Earth transition into an icehouse period?

• Tectonic activity.

• Feedback mechanisms.

• Increased volcanism.

What is orbital forcing?

A process which affects glacial/interglacial cyclicity due to changes in proximity to the sun.

How does the Earth’s distance from the Sun change seasonally?

• Perihelion → Earth is closest to the Sun during N hemisphere winter.

• Aphelion → Earth is furthest from the Sun during Northern hemisphere summer.

What are the three other major phases of orbital theory that control the insolation of Earth?

Eccentricity → change in the shape of orbit from circular to elliptical. 100,000 year cycles.

Obliquity → change in axial tilt from 21.8 degrees to 24.4 degrees.

Precession → axial wobble due to gravitational attraction from the Sun and Moon.

What is the current period we live in called?

The Holocene. Short inter-glacial.