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Past Abrupt Changes in Climate and Terrestrial Ecosystems
@IceAgeEcologist HiRes Workshop, June 1-3, 2015
Barry Carlsen
Jack WilliamsUniversity of Wisconsin-Madison
Kevin BurkeUniversity of Wisconsin-Madison
Matt McGloneLandcare Research, New Zealand
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Rapid Rates of Climate & Ecological Change: Two distinct sets of risk
Species Rate of Response >> Climate Change Adaptive lags; heightened extinction risk, may require management intervention
Species Rate of Response >> Rate of Climate Change Tipping points, regime shifts, ecological surprises
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Even slowest IPCC scenario is faster than anything in history of human civilization
Projected changes in global mean temperature by 2100AD
Holocene annual(?) temperature trends
Marcott et al. 2013 ScienceIPCC 2013 AR5 WGI Chap. 12 Fig. 12.5
Holocene: ~0.8ºC coolingRCP2.6 (low): 0.7-1.7ºC
How do we manage ecosystems experiencing rates of change we’ve never seen?
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Can species keep up?
IPCC 2013 AR5 WG2 Fig. SPM
Species movement capabilities vs. climate velocities
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Complex systems may have tipping points, alternative stable states, rapid regime shifts
Mean annual rainfall (mm)
Scheffer & Carpenter 2003 TREE; Staver et al. 2011 Science
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Abrupt Changes Common in the Past
PETM DO Events
Last deglaciation Holocene tree collapses
Zachos et al. 2005 Science, Rahmstorf 2003 GRL, Grootes et al. 1993 Nature, Booth et al. 2012 Ecology
PLEISTOCENE || HOLOCENE
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Causes of past abrupt ecological changes
Photo: The Destruction Company http://www.luxuo.com/membership/the-destruction-company.html
1) Strong extrinsic forcing (hammers),
2) Tipping points, thresholds, and other feedbacks intrinsic to ecological systems (canoes)
3) Feedbacks with other earth system components (loops)
Tropical Tree Density
Transpiration Rates
Precipitation Rates
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Each lets us answer different questions:
How quickly can ecological systems respond to rapid climate change?
Photo: The Destruction Company http://www.luxuo.com/membership/the-destruction-company.html
Where are the tipping points and tipping elements in ecological systems? Can we develop early warning signals?
What are the relative contributions of extrinsic and intrinsic processes to past abrupt changes?
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Extrinsic Forcing Case Study: Vegetation Responses to Last Deglaciation
(Grootes et al. 1993 Nature)
Temperature Variations Since the LGM
PLEISTOCENE || HOLOCENE
Large Climatic Forcing:• Global temperature: rose ~5ºC• Abrupt regional change: 9-
15ºC in 5-60 yrs
21,000 11,000 Modern15,000 7,000
%
Large Biotic Responses:• Species ranges shift by 102 to 103km• Reshuffle into no-analog communities
%
%
%
No Data
Williams et al. (2004) Ecological Monographs
SprucePollen
Ice IceIce
How fast did tree species respond?
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Gerzensee,Allerød warming
Ammann et al. 2013 P-Cubed
Pinus arrives (800 years)
Juniper expands (<8-16years)
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Meerfelder Maar,YD cooling
Rach et al. 2014 Nat. Geo.
Windiness increases & Tundra expands: (no lag)
YD onset at Greenland
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Kråkenes Lake,Holocene warming
Birks 2015 Holocene
Betula arrives: (700 years)
Artic flora collapse & Salix ↑ (no lag)
Heath expands (250 years)
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Intrinsic Tipping Points: Vegetation Responses to Holocene Aridification
North Africa: • Aridification between 9ka and 5ka• Grassland ->Desert• Abrupt and time-transgressive local
changes
North American Great Plains:• Aridification between 11ka and 6ka• Forest->Prairie, Dunes activate, etc.• Abrupt and time-transgressive local
changes
Hoeltzmann et al. 1998 GBCPhoto credit: Joe Mason
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North Africa
Shanahan et al. 2014 Nature Geo.
• Gradual insolation forcing• Regional aridification 9ka to 5ka• Locally abrupt changes• Time-transgressive & rapid local
declines in rainfall• Differential & rapid collapses of
species within sitesTime-transgressive changes in hydrology
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North Africa
Kropelin et al. 2008 Science
• Gradual insolation forcing• Regional aridification 9ka to 5ka• Locally abrupt changes• Time-transgressive responses
across sites• Differential timing among taxa
within sites
Lake Yoa
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Great Plains: Similar to North Africa
Williams et al. 2010 Geology
• Gradual insolation forcing• Regional aridification 11ka to 6ka• Multiple System Responses:
• Dunes activate, • C3->C4 grasslands, • Forest->Prairie, • Lake levels drop
• Locally rapid and time-transgressive shifts Time-transgressive changes in forest->prairie
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Summary1. Two distinct risks for ecological systems during rapid 21st-
century climate change: A. Failure of species to keep up with rapid climate changeB. Tipping points and ecological rates of response much faster than
environmental forcing
2. Many past abrupt events, caused by rapid extrinsic forcing, intrinsic tipping points, and vegetation-atmosphere feedbacks
3. Last deglaciation: Fast and slow vegetation responses to abrupt climate change: near-zero to centuries
4. Holocene aridification: regionally slow, locally abrupt. Caused by ecological tipping points? Can we model this?
5. Need more study of paired high-resolution studies of abrupt climatic & ecological change
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Thanks & AcknowledgmentsMatt McGlone & Kevin
Data Contributors Brigitta Ammann, Hilary Birks, Achim Brauer, André Lotter, Oliver Rach, Tim Shanahan, Willy Tinner, and Willem van der Knaap
Funding and Infrastructure:
Further Reading:Williams, J.W., Blois, J.L., & Shuman, B.N. (2011) Extrinsic and intrinsic forcing of abrupt ecological change: Case studies from the late Quaternary. Journal of Ecology, 99, 664-677.Williams, J.W. & Burke, K. (in press). Past abrupt changes in climate and terrestrial ecosystems. In Climate Change and Biodiversity (eds T. Lovejoy & L. Hannah).
Neotoma Paleoecology DBNSF
Bryson Climate, People, & Environment Program