atmospheric research can you gradually fall off a cliff? – a glimpse at complex, self-organising...
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Atmospheric Research
Can you gradually fall off a cliff?– A glimpse at complex, self-organising systems
Roger N. Jones
AIACC Training Workshop on Adaptation and Vulnerability
TWAS, TriesteJune 3-14 2002
Atmospheric Research
The awakening of complexity
Mechanical world of the 19th century
• Few mysteries left for science to solve
• The universal machine
• Mastery over nature
• The march of progress
• Modernism
The 20th century – transition
• Quantum physics
• Chaos and “strange attractors”
• isolated “frame of reference” exposed as a scientific construct
• search for a process to counterbalance reductionism
• Postmodernism
Atmospheric Research
Contributions to complex systems science
• Adam Smith “The invisible hand”• Einstein, Bohr, Pauling et al. – quantum physics• Schroedinger et al. – uncertainty• Turing and Von Neumann – self-replicating automata and game theory• Kuhn – the scientific process is linked to social processes • Prigogine – complex chemistry• Lorenz, Gleick et al. – chaos• Holland, Conway et al. – artificial life• Bak et al. – self organising systems• Arthur – law of increasing returns (economics)• Capra – role of eastern philosophyand many others
Atmospheric Research
Simple system
• Mechanistic• Replicable• Largely linear• Can be isolated from other systems• Predictable
Atmospheric Research
Complex system
• Organic/chaotic (often described as on the edge of chaos because both organised and chaotic behaviour are recognised)
• Non-replicable
• Cannot be isolated from other systems
• Non-linearity and thresholds both common
• Self-organising (self-adapting)
• Bifurcations occur over time
• Uncertainty is intrinsic
Atmospheric Research
Examples
• Qwertyuiop• VHS/Beta• DOS/CPM• Extinctions/radiation (evolution)
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Fractal patterns are “natural”
Atmospheric Research
Glacial cycles are driven by changes in the Earth’s orbit
Carbon dioxide and temperature last 420, 000 years
100
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0100,000200,000300,000400,000years before present
CO
2 (p
pm)
-10
0
10
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tem
pera
ture
(oC
)
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Holocene rainfall and evaporation – W. Victoria
Atmospheric Research
Atmospheric Research
Weather events
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CO2 emissions and concentrations
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Global warming
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Likelihood
Probability can be expressed in two ways:
1. Return period / frequency-based(Climate variability)
2. Single event(Mean climate change, one-off events)
Atmospheric Research
Return period / frequency-based probability
Recurrent or simple eventWhere a continuous variable reaches a critical level, or
threshold.
Eg. Extreme temperature (max & min), Extreme rainfall, heat stress, 1 in 100 year flood
Discrete or complex eventAn event caused by a combination of variables (an
extreme weather event)
Eg. tropical cyclone/hurricane/typhoon, ENSO event
Atmospheric Research
Frequency-based probability distributions
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Coping range under current climate
Stationary Climate & Coping Range
CopingRange
Vulnerable
Vulnerable
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Thresholds
A non-linear change in a measure or system, signalling a physical or behavioural change
Climate-related thresholds are used to mark a level of hazard
Atmospheric Research
Single-event probability
Singular or unique eventAn event likely to occur once only. Probability refers to
the chance of an event occurring, or to a particular state of that event when it occurs.
Eg. Climate change, collapse of the West Antarctic Ice Sheet, hell freezing over
Atmospheric Research
What is the probability of climate change?
1. Will climate change happen?• IPCC (2001) suggests that climate change is occurring with
a confidence of 66% to 90%
2. What form will it take?Uncertainties are due to:
• future rates of greenhouse gas emissions
• sensitivity of global climate to greenhouse gases
• regional variations in climate
• decadal-scale variability
• changes to short-term variability
Atmospheric Research
Range of uncertainty
TOTAL RANGE OF UNCERTAINTY
QUANTIFIABLE RANGE OF UNCERTAINTY
M1 M2 M3 M4
UNQUANTIFIABLEUNCERTAINTY
UNQUANTIFIABLEUNCERTAINTY
0
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0 100
Probability (%)
Sea
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ise
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Probability (%)
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ise
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Probability (%)
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eve
l Ris
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cm)
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25 cm
50 cm
75 cm
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Non-linear climate change
• Non-linear climate events - ice ages, Younger Dryas, collapse of the WAIS
• Climate surprises - climate events that occur unexpectedly
• Climate surprises are likely to occur on a regional basis under climate change but when and where remains unknown.
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System responses
• Resistance (e.g. seawall)
• Resilience (e.g. regrowth, rebuilding after storm or fire)
• Adaptation (adjustments made in response to stress)
• Transformation (old system stops, new one starts)
• Cessation (activity stops altogether)
Atmospheric Research
Can you gradually fall off a cliff?
Yes, if you use a model
But not in the real world