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Uncertainty, Lags, and Nonlinearity:
Challenges to Governance in a Turbulent World
Thomas Homer-Dixon
CIGI Chair of Global Systems
Balsillie School of International Affairs
Waterloo,Canada
May 7 2009
UNCERTAINTY
LAGS
NONLINEARITY
OPENNESS
UNCERTAINTY
LAGS
NONLINEARITY
OPENNESS
UNCERTAINTY
LAGS
NONLINEARITY
OPENNESS
We need to shift from seeing the world
as composed mainly of
MACHINES
to seeing it as composed mainly of
COMPLEX SYSTEMS
Whereas MACHINES
• can be taken apart, analyzed, and fully
understood (they are no more than the sum
of their parts)
• exhibit “normal” or equilibrium patterns of
behavior
• show proportionality of cause and effect,
and
• can be managed because their behavior
predictable . . .
COMPLEX SYTEMS
• are more than the sum of their parts (they
have emergent properties)
• can flip from one pattern of behavior to
another (they have multiple equilibriums)
• show disproportionality of cause and effect
(their behavior is often nonlinear, because
of feedbacks and synergies), and
• cannot be easily managed because their
behavior is often unpredictable.
We’re moving from a world of
RISK
to a world of
UNCERTAINTY
(unknown unknowns)
So, we must move from “management” to
Complex Adaptation
Battisti and Naylor, “Historical warnings of future food insecurity with unprecedented seasonal heat.”
Science (9 January 2009): 240-44
Battisti and Naylor, “Historical warnings of future food insecurity with unprecedented seasonal heat.”
Science (9 January 2009): 240-44
IPCC 2007
UNCERTAINTY
LAGS
NONLINEARITY
OPENNESS
LAGS
• Between emission and climate response
• Between cuts to emissions and reduction of
warming
• Between policy decision to change energy
infrastructure and completion of this change
“ [We show] that to hold climate constant
at a given global temperature requires near
zero future carbon emissions. . . . As a
consequence, any future anthropogenic
emissions will commit the climate system to
warming that is essentially irreversible on
centennial timescales.”
Matthews, H. D., and K. Caldeira (2008), “Stabilizing climate requires
near-zero emissions,” Geophys. Res. Lett.
“[The] climate change that takes place due to increases
in carbon dioxide concentration is largely irreversible for
1,000 years after emissions stop. Following cessation of
emissions, removal of atmospheric carbon dioxide
decreases radiative forcing, but is largely compensated
by slower loss of heat to the ocean, so that atmospheric
temperatures do not drop significantly for at least 1,000
years. Among illustrative irreversible impacts that should
be expected if atmospheric carbon dioxide
concentrations increase from current levels near 385
parts per million by volume (ppmv) to a peak of 450–600
ppmv over the coming century are dry-season rainfall
reductions in several regions comparable to those of the
‘‘dust bowl’’ era and inexorable sea level rise.”
Solomon et al, “Irreversible climate change due to carbon dioxide emissions,” PNAS
(February 10 2009).
Hansen, Atmos. Chem. Phys. 7 (2007): 2287-2312.
UNCERTAINTY
LAGS
NONLINEARITY
OPENNESS
0.25
Ice Accumulation Rate
(meters per year)
0.2
0.15
0.1
0.05
0
13000
12500
12000
11500
Years before Present
11000
10500
More rapid warming at poles
One reason: Ice-albedo feedback
Atmospheric
warming
radiative
Increased ocean
positive feedback,
absorption of
sun’s energy
fast
Lower reflectivity
of ocean surface
Melting of
ice
2008
4.52 mK2
Jakobshavn Ice Stream in Greenland
Discharge from major
Greenland ice streams
is accelerating markedly.
Source: Prof. Konrad Steffen,
Univ. of Colorado
Atmospheric
warming
Release of
CO2
carbon cycle
positive feedback,
potentially fast
Rotting and burning
of organic
matter
Death of
forests
Atmospheric
warming
carbon cycle
positive feedback,
slow
Increased
airborne
fraction
Decreased
efficiency of
carbon sinks
Declining efficiency of the ocean sink
• Up to 30 percent decrease in the
efficiency of the Southern Ocean
sink over the last 20 years
• Strengthening of the winds around
Antarctica increases exposure of
carbon-rich deep waters
• Strengthening of the winds due to
global warming and the ozone hole
Le Quéré et al. 2007, Science
Atmospheric
warming
Release of
CH4
and CO2
carbon cycle
positive feedback,
potentially fast
Rotting
of organic
matter
Melting of
permafrost