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