Multiscale regime shifts and
planetary boundaries
Hughes et al (2013)
Kimberly Duong
January 6, 2016
Regime Shifts
• Loosely defined by authors as “major changes in
ecosystems” that occur when the climate or
biosphere surpasses a tipping point
• In resilience theory, the stability landscape is
characterized by peaks and valleys
• Interacting causal networks of slow and fast
processes erode the resilience of a system
• Anthropogenic activities change shape and depth
of valleys and influence the tendency towards or
away from regime shifts
Tipping point
• Nonlinear relation between driver (or cause)
of a regime shift and the eventual state of an
ecosystem in equilibrium
• Slope of relation becomes steeper if positive
feedback loops are present
• Smooth, slow or incremental ecological
change over time may be the lagged transient
response of ecosystem that has passed the
tipping point
Slow responses
• Regional and planetary scale responses can
occur slowly during regime shifts
– Example: response to global warming after last ice
age took 1000s of years to happen
• Important: transgressing global tipping points
is unlikely to manifest as sudden
• The speed of transition is not important, but
the presence or absence of tipping points is
Dinosaurs
• Dinosaur extinction at the end of the
Cretaceous prompted mammals to expand in
population
• This is an irreversible transition, a planetaryscale regime shift
• At the end of the Cretaceous, multiple cycles
of climatic cooling stressed Cretaceous
ecosystems, bringing it closer to a global
tipping point that occurred in the form of a
meteor impact
Drivers of change
• Major regional/global drivers of ecological regime
shifts
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Climate change
Land-use change and harvesting
Direct manipulation of biogeochemical cycles
Toxin release
Invasive species
• Important to distinguish external drivers from
internal responses
– (ex) Habitat fragmentation is not a driver of change.
It’s an internal response to overharvesting (the driver)
Conclusion
1) Don’t confuse rate of change (may be fast or
slow) with presence of absence of tipping point. A
slow rate of change or lagged response doesn’t
indicate absence of tipping point.
2) Don’t confuse internal responses for external
drivers.
– Anthropogenic drivers = climate change,
overharvesting
– Internal responses = habitat fragmentation,
biodiversity loss, emergent diseases
Source
• Hughes, T. P., Carpenter, S., Rockström, J.,
Scheffer, M., & Walker, B. (2013). Multiscale
regime shifts and planetary boundaries.
Trends in Ecology & Evolution, 28(7), 389-395.