Quaternary Environments Paleoclimatic Reconstruction

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