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

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

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?

Can species keep up?

IPCC 2013 AR5 WG2 Fig. SPM

Species movement capabilities vs. climate velocities

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

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

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

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?

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?

Gerzensee,Allerød warming

Ammann et al. 2013 P-Cubed

Pinus arrives (800 years)

Juniper expands (<8-16years)

Meerfelder Maar,YD cooling

Rach et al. 2014 Nat. Geo.

Windiness increases & Tundra expands: (no lag)

YD onset at Greenland

Kråkenes Lake,Holocene warming

Birks 2015 Holocene

Betula arrives: (700 years)

Artic flora collapse & Salix ↑ (no lag)

Heath expands (250 years)

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

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

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

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

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

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