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Quaternary Environments
Paleoclimatic Reconstruction
Paleoclimatic Reconstruction
“…paleoclimatic data provide the basis for
testing hypotheses about the causes of
climatic change. Only when the causes of
past climatic fluctuations are understood
will it be possible to fully anticipate or
forecast climatic variations in the future
(Bradley and Eddy, 1991).” (Bradley 1999)
Thresholds
Nonlinear responses
 Critical thresholds

http://kevin.atkinson.dhs.org/fractals/
Strange Attractors

Lorenz attractor
 Meteorologist,
1963
http://www.geocomplexity.com/Global_climate.htm
Signal to Noise Ratio
Proxy records catalog the phenomenon in
which we are interested. This is called
signal.
 At the same time they filter that signal and
also respond to other drivers. This we call
noise.
 If you examine the signal to noise ratio you
can determine the quality of the record.

Calibration
Direct information on the phenomenon or
other proxy materials are used to
demonstrate the relationship.
 The principle of uniformitarianism.
 Never 100% accurate.

Analog Situations
Comparable situations in the past
 No-Analog situations
 Multiple proxies

Extent

Spatial coverage
– Size of catchment
 Dendrochronology – Coherent climate signals
 Packrats – Range from midden along with
coherent ecosystems
 Palynology

Temporal coverage
– 1,000 years on average
 Palynology – often 10,000 years
 Marine Sediments – 100,000 years
 Dendrochronology
Resolution

Sampling interval
– Annual
 Lake Sediments – 50 - 200 years
 Marine Sediments – 500 - 1000 years
 Dendrochronology
Sedimentation Rate
 Non-Continuous Records

 Glacial Advances
Frequency Dependence
Low Frequency Signal
 High Frequency Signal

Inertia

Response Time - Lags
Assemblages – 100 years for the
vegetation to respond to climate change
 Insect Assemblages – Quick generation time,
so change very quickly with climate
 Pollen

Autocorrelation
 Dendrochronology
- Climate responses
Climatic Forcing Factors
Proxies record climate change
 Also record forcing factors

 Volcanic
aerosols
 Dust in ice cores
 Carbon Dioxide
 Methane
 Nitrous Oxide
Feedbacks
Positive Feedbacks
 Negative Feedbacks

http://www.geocomplexity.com/Global_climate.htm
Dating

Utmost importance to determine timing of
events
 Synchronicity
of timing
 Forcing factors
 Lagged timing
Levels of Analysis

Level I
 Field
data collection, analysis, and
measurements

Level II
 Calibrated

and converted to paleo records
Level III
 Regionalized
 Synthesis
paleo records
Models
Simplify a system to its basic components
 Types of Models

 Physical
Models
 Globe
 Computer
Models
 GCMs
 Conceptual
 Flow

Models
chart
Test Hypotheses