Earth System Science: The History of our Planet
QUATERNARY EARTH SYSTEM DYNAMICS
1. INTRODUCTION TO THE QUATERNARY I : Climatic and environmental change
2. INTRODUCTION TO THE QUATERNARY II : Palaeoclimate reconstruction
3. ICE AGE EARTH : THE NORTHERN HEMISPHERE I
4. ICE AGE EARTH : THE N...
Earth System Science: The History of our Planet
GEO1121
QUATERNARY EARTH SYSTEM DYNAMICS
1. INTRODUCTION TO THE QUATERNARY I : Climatic and environmental change
2. INTRODUCTION TO THE QUATERNARY II : Palaeoclimate reconstruction
3. ICE AGE EARTH : THE NORTHERN HEMISPHERE I
4. ICE AGE EARTH : THE NORTHERN HEMISPHERE II
5. ICE AGE EARTH : THE SOUTHERN HEMISPHERE
6. ICE AGE EARTH : ASIA AND THE TROPICS
7. RAPID CLIMATE CHANGE IN THE QUATERNARY
8. THE PRESENT INTERGLACIAL : THE HOLOCENE
9. QUATERNARY INTERGLACIALS : ANALOGUES FOR THE FUTURE
10. HUMANS IN THE QUATERNARY : HUMAN EVOLUTION
11. HUMANS IN THE QUATERNARY : THE PALAEOLITHIC TO THE NEOLITHIC
12. HUMANS IN THE QUATERNARY : DAWN OF THE ANTHROPOCENE
13. HUMANS IN THE QUATERNARY : THE LAST 1000 YEARS
, Earth System Science: The History of our Planet
GEO1121
(1)
INTRODUCTION TO THE QUATERNARY I : Climatic and environmental change
CLIMATE CHANGE IN CONTEXT
May 2019 - University of Exeter declares climate and environment emergency
We passed the 400ppm mark on 6th of May 2015, now around 411
(ppm = parts per million)
THE QUATERNARY PERIOD
Deep time : everything prior to the quaternary
The Quaternary : the current and most recent of the three periods of the Cenozoic Era. It follows the
Neogene Period
Pleistocene : the first and majority part of the quaternary 2.6mil-11,000 years ago
Holocene : 11.5k to now
Anthropocene : the commencement of significant human impact upon the earth
Hominids :
‘NATURAL’ CLIMATE VARIABILITY
Layers of snow trap air bubbles, which can be studied to reveal ppm in the atmosphere over time
The oldest record we have is 800,000 years ago, an ice core in Vostok Iceland.
Amount of CO2 has increased 10% in our lifetime
When we were born we were already at higher levels than any measure recorded in our history - up to
the 800,000 year mark
ANTHROPOGENIC CLIMATE CHANGE
Evidence is everywhere: atmospheric composition, temperature rise, sea level rise (sea temps - ice
melt)
By 2100, global average temperatures will probably be 5 to 12 standard deviations above the
Holocene temperature mean
WHY THE QUATERNARY?
Geologically it is recent
Coincides with the evolution of hominids and the birth of ‘modern society’
Provides long term context for understanding the Earth System
A BRIEF HISTORY OF QUATERNARY SCIENCE
Differing interpretation of geomorphological features in the landscape
‘Erratics’ - rock that differs in size and type from those in the area often very large
- Eg. Yaeger rock, Washington - 400 tons
- Champlain Mountain, Maine
- Saunton Sand, N Devon - Pink Granite (from Scotland…!?)
, Earth System Science: The History of our Planet
GEO1121
‘Till’ - unsorted sediment, variety of rock types and sizes, found across northern hemisphere
Large scale geomorphological features
- Eg, ‘Parallel roads’, Glen roy, scotland
‘Catastrophism’ vs ‘Uniformitarianism’
C = rocks and sediments covering landscape, products of biblical flood.
Earth's surface the result of succession of catastrophes
Features form during individual events
U = physical, chemical, biological laws that operate today also operated in the past
Earth history dominated by small scale events and processes ‘gradualism’
Scottish Enlightenment produced the modern geologists
- David Hume (1711-1776)
- “All inferences from experience suppose that the future will resemble the past”
- James Hutton (1726-1797)
- “The past is the key to the future”
- Charles Lyell (1797-1875)
- “The present is the key to the past”
1787 - Bernard Kuhn (Switzerland) ‘erratics are dumped by glaciers’
1790 - James Hutton visited and agreed
Charles Darwin - 1839 - ‘Shorelines are raised beaches of marine origin’
Louis Agassiz - 1840 - ‘Shorelines were cut by freeze-thaw processes of an ice-dammed loch,
created by a glacier which formed during the Younger Dryas climatic reversal’
1837 - Agassiz lectured on ‘Ice Ages’ at Swiss Society of Natural Sciences, Most Scientists thought
the earth had cooled gradually from molten state
1840 - Wrote book ‘Study on Glaciers’ and lectured with Buckland and Lyell on cyclic ‘Ice Age
Theory’ at the Geological Society, London
Lack of a plausible mechanism to explain climatic changes required to drive ice sheet formation
1842 - Joseph Adhémar introduced concept of orbital ‘eccentricity’
Shape of the earth’s elliptical orbit oscillates from more circular to less circular
Variations in eccentricity affect seasonality (i.e. mild winters, cool summers; cold winters, hot
summers)
1864 - James Croll wrote a paper suggesting that variations in eccentricity could drive cyclic ice ages
(i.e. cool summers – year-round ice – glaciers/ice sheets)
Eccentricity :
‘Insolation’ : solar radiation that reaches the earth's surface.
Milutin Milanković (1879-1958) - Developed mathematical explanation for climate change
In 1920, published calculations of heat changes at different latitudes, and periodicities of these
changes
Identified 65°N as place where biggest insolation changes occur
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