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03. Scott Hocknull - Dinosaur Man

CLIMATE OVER THE LAST 500,000 YEARS

The last 0.5Ma

Graph of CO2 (green graph), temperature (blue graph) and dust concentration (red graph) measured from the Vostok, Antarctica ice core as reported by Petit et al, 1999. Higher dust levels are believed to be caused by cold, dry periods. Graph: Wikimedia Commons. Permission is granted to copy, distribute and/or modify this under the terms of the GNU Free Documentation Licence.

The last 500,000 years (0.5Ma) have been marked by very distinctive glacials (cold troughs) and inter-glacials (warm peaks). Temperature has fluctuated from up to 4°C warmer to 8°C colder than today.

What major factors affected the Australian continent?

Humans first arrived in Australia about 50,000 years ago (or 50ka; 1ka = 1000 years.) To understand how climate has affected our fauna and flora without human influence, we therefore need to concentrate on the fossil record that is more than 50,000 years old. We also need to focus on a time of sudden climate shifts.

As well as the temperature cycling between warm and cold, there have been changes in rainfall patterns. Australia has experienced intensifying aridity that overrides these global climate wobbles.

This intensifying aridity is the most significant change in Australia’s climate over the last 4-5 million years. Our deserts, rainforests, reefs and woodlands have all been affected by this change.

INTENSIFYING aridity
Central Australia Southern Australia Northern Australia
4-1 million years ago ~500,000 years ago ~300,000 years ago

Gibber-Stony Desert Formation Lakes Drying

Lake Drying
Arid Weathering

Lake Drying
Grasslands increase
Rainforest change
Weakened Monsoons
Dust increases
Sea Surface Temperature increases

How did our animals respond to this change?