Glaciations

Glaciations

A period when global climate cools significanltly

What happens in glaciations?

Continental ice sheets expand, sea level drop, ecosystems shift.

Repeated glaciations in the last ___ million years

2.6 my

~___ major glaciations in the past million years

~10

major glaciations in the last _

3, 150,000 years

Last Glacial Maximum(LGM) was ___ years ago.

~18,000 ya

Last Glacial Maximum (LGM)

Sheets of ice, sea level drop ~120m

Causes of Glaciation

Linked to variation in Earths Orbit, Eccentricity, Tilt, Orbital precession

Linked to variation in Earths Orbit

Cyclic variation Affects solar heating, Milankovitch Cycles

Eccentricity

Shape of orbit

Eccentricity happen when ..

Orbits shifts between circular and elliptical

Eccentricity was ____

~95,000-100,000 years ago

Eccentricity affects the…

Distance to the sun

More elliptical:

Cooler summers, ice sheets grow, ice and snow don’t melt

Obliquely - Tilt

Earth can slightly shift how tilted it is

Tilt was roughly…

~ 41,000 years ago

Larger Tilt

Stronger seasons, warmer summers (more melting), cooler winters (more snow, cannot offset melting)

Smaller tilt

Cooler summers, glaciers grow

Precision - Wobble

Changes timing of seasons

Wobble - changing timing of seasons