Extracting a Climate Signal Extracting a Climate Signal fromfrom

169 Glacier Records (2005)169 Glacier Records (2005) Johannes OerlemansJohannes Oerlemans: Professor of : Professor of

Meteorology, Faculty of Physics and Meteorology, Faculty of Physics and Astronomy, Utrecht University (the Astronomy, Utrecht University (the Netherlands)Netherlands)

Research interests: Research interests: glaciers, sea-level glaciers, sea-level change, palaeoclimatology, and change, palaeoclimatology, and dynamic meteorologydynamic meteorology

ScienceScience: 3 times: 3 times NatureNature: 8 times: 8 times

Supplement to Supplement to Oerlemans (2005)Oerlemans (2005)

Complexity in Natural Complexity in Natural Landform Patterns Landform Patterns

(1999)(1999) Brad WernerBrad Werner, Professor of Geophysics, , Professor of Geophysics, Scripps Institution of OceanographyScripps Institution of Oceanography

All degrees from California Institute of All degrees from California Institute of TechnologyTechnology

Focused on complex systems, self-Focused on complex systems, self-organization, and geophysical pattern organization, and geophysical pattern formationformation

Several publications in both Several publications in both ScienceScience and and Nature Nature on these topicson these topics

The PremiseThe Premise Landforms are simple in their form, Landforms are simple in their form,

occupying only a small fraction of all occupying only a small fraction of all possible formspossible forms

At the same time, landforms are complex At the same time, landforms are complex due to several interacting process due to several interacting process componentscomponents PhysicalPhysical ChemicalChemical BiologicalBiological

Natural patterns are non-linear, dependent Natural patterns are non-linear, dependent on an infinite amount of dynamic variableson an infinite amount of dynamic variables A symptom of formation in an open systemA symptom of formation in an open system

How Do We Model Natural How Do We Model Natural Patterns?Patterns?

A modeling approach must provide a A modeling approach must provide a way to select the relevant internal way to select the relevant internal dynamic variables from an infinite array dynamic variables from an infinite array of those characterizing the systemof those characterizing the system

Must also account for changes in the Must also account for changes in the environment external to the systemenvironment external to the system

ReductionismReductionism and and UniversalityUniversality are are the existing modeling approachesthe existing modeling approaches Both inadequate for meeting the above Both inadequate for meeting the above

requirementsrequirements

Reductionism Reductionism Contends the earth is too large and Contends the earth is too large and

complex to study as a wholecomplex to study as a whole Focuses on the irreducible unitFocuses on the irreducible unit

Micro spatial and temporal scalesMicro spatial and temporal scales Infers the behavior of a system Infers the behavior of a system

through the sum of its partsthrough the sum of its parts Reductionism is inadequate due Reductionism is inadequate due

to its inability to account for the to its inability to account for the external environmentexternal environment

Presents complex systems in their Presents complex systems in their simplest formsimplest form

Focuses on generalized principlesFocuses on generalized principles Macro spatial and temporal scalesMacro spatial and temporal scales

Universality is inadequate due to Universality is inadequate due to its oversimplification of internal its oversimplification of internal variables and the external variables and the external environment, making it difficult environment, making it difficult to quantify and test modelsto quantify and test models

UniversalityUniversality

Example:Example: William William Morris Davis’ model Morris Davis’ model of the “Geographical of the “Geographical Cycle” (1909)Cycle” (1909)

UniversalityUniversality

http://www.staff.amu.edu.pl/~sgp/gw/wmd/http://www.staff.amu.edu.pl/~sgp/gw/wmd/wmdfig.htmlwmdfig.html

Hierarchical ModelingHierarchical Modeling

Variables operate within a characteristic Variables operate within a characteristic temporal scaletemporal scale Fast variables occur at a micro scaleFast variables occur at a micro scale Slow variables occur at a macro scaleSlow variables occur at a macro scale

Fast variables are constrained by slow Fast variables are constrained by slow variablesvariables

Slow variable behavior is generated by Slow variable behavior is generated by interaction of fast variablesinteraction of fast variables

Internal dynamic variables within a Internal dynamic variables within a system correspond to external system correspond to external environmental variablesenvironmental variables

Hierarchical ModelingHierarchical Modeling

Each hierarchical level is testable with Each hierarchical level is testable with respect to:respect to: Dynamic relationship with faster variable Dynamic relationship with faster variable

(child)(child) Dynamic relationship with slower variable Dynamic relationship with slower variable

(parent)(parent) Influence from external environmentInfluence from external environment

Change in the external environment may Change in the external environment may affect dynamic relationships with faster affect dynamic relationships with faster and slower variablesand slower variables

Hierarchical ModelingHierarchical Modeling

QuestionsQuestions

Regarding Oerlemans article: Regarding Oerlemans article: Information is presented in a very dense Information is presented in a very dense format. Was it clear to you which results format. Was it clear to you which results were most significant, and what were were most significant, and what were they?they?

Is there any one aspect of the way the Is there any one aspect of the way the article was written or presented that article was written or presented that hindered your comprehension of the hindered your comprehension of the subject matter?subject matter?

The author states that a 25% The author states that a 25% increase in precipitation is needed to increase in precipitation is needed to compensate for mass loss due to a 1 compensate for mass loss due to a 1 Kelvin warming. It has been shown Kelvin warming. It has been shown in other studies that global warming in other studies that global warming causes increased precipitation. Is causes increased precipitation. Is there an equilibrium? Is there a there an equilibrium? Is there a point where the dynamics will change point where the dynamics will change once a threshold has been reached? once a threshold has been reached?

How do glacier studies help to How do glacier studies help to reconstruct the past?reconstruct the past?

Can they provide information about Can they provide information about local/regional paleoenvironments? Or arelocal/regional paleoenvironments? Or arethey global in scale?they global in scale?

How does glacier data contribute to local How does glacier data contribute to local paleoecological/paleoclimaticpaleoecological/paleoclimaticstudies?studies?

Can modeling achieve an accurate Can modeling achieve an accurate picture of the world? Is it designed picture of the world? Is it designed to?to?

Do we expect to? Do we place too Do we expect to? Do we place too much or too little stock in it?much or too little stock in it?

When is it appropriate? When is it not When is it appropriate? When is it not appropriate?appropriate?

What are the ways that we can What are the ways that we can reduce/remove bias from modeling? reduce/remove bias from modeling?

Where does Oerlemans’ recent work Where does Oerlemans’ recent work fit into the classification of models fit into the classification of models that Werner describes?that Werner describes?

Do you think that Oerlemans’ model Do you think that Oerlemans’ model is just one tier of Werner’s is just one tier of Werner’s hierarchical model?hierarchical model?

Using glacial characteristics as an example, identify the internal dynamical variables and corresponding external environmental parameters.

How do these studies fit into the How do these studies fit into the sub-fields of Resource Geography sub-fields of Resource Geography and GI Science? and GI Science?