Quaternary EnvironmentsQuaternary EnvironmentsPaleoclimatic ReconstructionPaleoclimatic Reconstruction
Paleoclimatic ReconstructionPaleoclimatic Reconstruction
“… “…paleoclimatic data provide the basis for paleoclimatic data provide the basis for testing hypotheses about the causes of testing hypotheses about the causes of climatic change. Only when the causes of climatic change. Only when the causes of past climatic fluctuations are understood past climatic fluctuations are understood will it be possible to fully anticipate or will it be possible to fully anticipate or forecast climatic variations in the future forecast climatic variations in the future (Bradley and Eddy, 1991).” (Bradley 1999)(Bradley and Eddy, 1991).” (Bradley 1999)
ThresholdsThresholds
Nonlinear responsesNonlinear responses Critical thresholdsCritical thresholds
http://kevin.atkinson.dhs.org/fractals/
Strange AttractorsStrange Attractors
http://www.geocomplexity.com/Global_climate.htm
Lorenz attractorLorenz attractor Meteorologist, 1963Meteorologist, 1963
Signal to Noise RatioSignal to Noise Ratio Proxy records catalog the phenomenon in Proxy records catalog the phenomenon in
which we are interested. This is called which we are interested. This is called signal.signal.
At the same time they filter that signal and At the same time they filter that signal and also respond to other drivers. This we call also respond to other drivers. This we call noise.noise.
If you examine the signal to noise ratio you If you examine the signal to noise ratio you can determine the quality of the record.can determine the quality of the record.
CalibrationCalibration Direct information on the phenomenon or Direct information on the phenomenon or
other proxy materials are used to other proxy materials are used to demonstrate the relationship.demonstrate the relationship.
The principle of uniformitarianism.The principle of uniformitarianism. Never 100% accurate.Never 100% accurate.
Analog SituationsAnalog Situations Comparable situations in the pastComparable situations in the past No-Analog situationsNo-Analog situations Multiple proxiesMultiple proxies
ExtentExtent Spatial coverageSpatial coverage
Palynology – Size of catchmentPalynology – Size of catchment Dendrochronology – Coherent climate signalsDendrochronology – Coherent climate signals Packrats – Range from midden along with Packrats – Range from midden along with
coherent ecosystemscoherent ecosystems Temporal coverageTemporal coverage
Dendrochronology – 1,000 years on averageDendrochronology – 1,000 years on average Palynology – often 10,000 yearsPalynology – often 10,000 years Marine Sediments – 100,000 yearsMarine Sediments – 100,000 years
ResolutionResolution Sampling intervalSampling interval
Dendrochronology – AnnualDendrochronology – Annual Lake Sediments – 50 - 200 yearsLake Sediments – 50 - 200 years Marine Sediments – 500 - 1000 yearsMarine Sediments – 500 - 1000 years
Sedimentation RateSedimentation Rate Non-Continuous RecordsNon-Continuous Records
Glacial AdvancesGlacial Advances
Frequency DependenceFrequency Dependence Low Frequency SignalLow Frequency Signal High Frequency SignalHigh Frequency Signal
InertiaInertia Response Time - LagsResponse Time - Lags
Pollen Assemblages – 100 years for the Pollen Assemblages – 100 years for the vegetation to respond to climate changevegetation to respond to climate change
Insect Assemblages – Quick generation time, Insect Assemblages – Quick generation time, so change very quickly with climateso change very quickly with climate
AutocorrelationAutocorrelation Dendrochronology - Climate responsesDendrochronology - Climate responses
Climatic Forcing FactorsClimatic Forcing Factors Proxies record climate changeProxies record climate change Also record forcing factorsAlso record forcing factors
Volcanic aerosolsVolcanic aerosols Dust in ice coresDust in ice cores Carbon DioxideCarbon Dioxide MethaneMethane Nitrous OxideNitrous Oxide
FeedbacksFeedbacks Positive FeedbacksPositive Feedbacks Negative FeedbacksNegative Feedbacks
http://www.geocomplexity.com/Global_climate.htm
DatingDating Utmost importance to determine timing of Utmost importance to determine timing of
eventsevents Synchronicity of timingSynchronicity of timing Forcing factorsForcing factors Lagged timingLagged timing
Levels of AnalysisLevels of Analysis Level ILevel I
Field data collection, analysis, and Field data collection, analysis, and measurementsmeasurements
Level IILevel II Calibrated and converted to paleo recordsCalibrated and converted to paleo records
Level IIILevel III Regionalized paleo recordsRegionalized paleo records SynthesisSynthesis
ModelsModels Simplify a system to its basic componentsSimplify a system to its basic components Types of ModelsTypes of Models
Physical ModelsPhysical Models GlobeGlobe
Computer ModelsComputer Models GCMsGCMs
Conceptual ModelsConceptual Models Flow chartFlow chart
Test HypothesesTest Hypotheses