1. Emergent Properties of Coupled Systems
Presenter: B. Turner; Moderator: J. Heffernan; Discussants: Cambridge Group

2. Definitions & Clarifications
Emergence
Is Not: “whole = more than sum of parts” (unexplainable)
Is: patterns arising from many simple interaction of complex systems (knowable but surprise)
CHES emergence
ideally involves coupling, both subsystem
some examples = focus on one subsystem
In almost all cases of emergence in CHES ≠ dealing with “strong” emergence (as in philosophical questions of epistemology or ontology) but with “weak” emergence (complexity of interactions = nonlinear responses)

3. Types of CHES Emergence
Aggregate attributes (system-wide attributes?) of the CHES
vulnerability or resilience of CHES
Flip or switch of CHES (classical emergence)
tipping points/elements = trajectories of change
can be in one subsystem
complex system & earth system science

4. Vulnerability & Resilience
Complimentary but different framings of CHES characteristics
V = weakest part of system (historically in human subsystem

6. Vulnerability & Resilience
Complimentary but different framings of CHES characteristics
V = weakest part of system (historically in human subsystem)
R = defines V as antonym of R

7. Meanings
V = degree to which CHES or some part likely to experience harm due to exposure
exposure, sensitivity, coping capacity/resilience
R = the amount of disturbance a system can absorb and remain within the same state or domain of attraction
Alt.: capacity to self organize or learn and adapt
V = largely from social science; R = from ecological science

8. Applications for CHES T’s Pivots V R
CHES, Environmental Services (ES), Tradeoffs (T) [Emergence?] V
From social science for human subsystem
Minimal attention to ES beyond provisioning kind and to processes of env. subsystem, especially with CHES in mind
Calls for T analysis; few attempted
Virtually no attention to emergence R
From ecological science with framework drawn almost wholly from it
Strong attention to ES; core idea
Attention to tradeoffs, both economic and physical [metrical]
Attention to tipping points/elements [largely from environmental science]

9. Therefore
V = only beginning to address the pivots & then by only a small portion of the practitioners adhering normal science
Not clear that emergent properties have been identified for CHES or its subsets (e.g., coping/adaptive capacity)
R = grounded in the pivots & all practitioners adhere to normal science
Some emergent properties advanced
All drawn from biophysical world
Not clear they are applicable to both subsystems
E.g., key = slow acting variables which tend to be macro-scale in kind

10. Tipping Points & Elements
TP = threshold condition in which a small perturbation qualitatively alters state of system
Emanates from climate sciences (focused on changes in biophysical world)
TE = significant variation of parameters controlling system  qualitative change which may not register immediately (time interval)
Notion that direct human action involved

11. Lenton, T. M. , et al. 2008. Tipping elements in the Earth’s climate
Lenton, T.M., et al Tipping elements in the Earth’s climate. Proc. Natl. Acad. Sci. U.S.A. 105, 1785–1793.

12. Coupled system tipping: possible Maya case
Climate change: < wet & > dry seasons
< evapotranspiration
< precipitation
< P capture [> > soils maintenace costs]
Hurricanes:
? Landscape walls
Soil: > temp
< moist
> reservoirs
> wetland agr < 150 m amsl
> invasive
bracken
fern [> agr costs]
Preclassic flush of soil and nutrients
[countered by terraces +]
Influx Maya clays; increase of seasonal bajo forest
>150 m
karst
deep aquifer

13. Commonalities?
Examples of increased V/decreased R & tipping points in CHES
Maya, Angkor Watt, Aral Sea
Move to new, qualitatively different state of CHES state
The environmental subsystem appears to recover in somewhat modified state
Including northern part of Aral Sea
Fewer examples of human subsystem recovery and environment does not
Exceptions: Leadville, Co.