Will Steffen

Global Change and the Earth System:A Planet in Transition

In Memoriam

Michael Raupach1950‐2015

Outline of the talk

1. Planetary machinery

2. The Earth as a system

3. The Anthropocene

1. Planetary Machinery:Building from the pieces

The “Bretherton Diagram”, 1980s

The Tyranny of the Atmosphere

IPCC 2001

Betts et al. 2001

Deforestation and Air Temperature

BAHC: Measuring land‐atmosphere fluxes

FLUXNET: http://public.ornl.gov/fluxnet/ecoregions.cfm

Studying the Siberian Carbon Cycle

Royal Society 2009

The Global Carbon Cycle

Towards Earth System Models

Petoukhov et al. 2000; Ganopolski et al. 2001

Photos: Tas van Ommen, Australian Antarctic Division

2. The Earth as a System

Sources: Petit et al. 1999; Scheffer 2009

The Earth as a Complex System

Glacial state Interglacial (warm) state

Sources: Petit et al. 1999; Scheffer 2009

The Earth as a Complex System

Limit Cycles

CO2

Temperature

CH4

Temperature rise: Beyond the envelope of natural variability?

Implications of accelerating climate changeIPCC temperature projections

IPCC 2013

2

4

3

5

6

1

0

Global  Tempe

rature (°C)

IPCC Projections2100 AD

Now

Earth System moves to a new state?

IGBP PAGES

Committed

Return towards aHolocene-like state?

Tipping Point?

Transition to a new, muchhotter state of the

Earth System?

Climate as a complex system

Tipping Elements in the Earth System

Source: Schellnhuber, after Lenton et al, PNAS, 2008

ENSOTriggering

IndianMonsoon

Transformation

Bodele DustSupply Change?

Bistability ofSaharan

Vegetation

Bistability /Collapse ofAmazonian

Forest?

ReducedPerformance

of MarineCarbon Pump

TibetanAlbedo Change?

Tipping Elements: Interactions & Complex Connections

Source: Schellnhuber 2008

Change in the Global Carbon Cycle

Source: Raupach and Canadell 2010;Global Carbon Project

Terms in the global carbon budget for 1850 - 2008

What does the AF trend tell us?

1. Sink responses to climate change

2. Nonlinear responses to increasing CO2, mainly oceanic

3. Departure of CO2 emissions from exponential growth

4. Volcanic eruptions

trajectory ofextrinsic forcing

feedback responses of sink processes to changes in climateand atmospheric CO2.

Sink Rates, 2014

Total

Land

Ocean

Raup

achet al. 2014, B

G

Atmosphere

Land

Ocean

Distrib

ution (Fraction)

Canade

ll et al. 2007, PNAS

Fractions, 2006

3. The Anthropocene

Environmental Change through Earth History

Zalasiewicz and Williams 2009

Human Development andEarth System Dynamics

Evolution of fully modern humans in Africa

Hunter-gatherer societies only

Beginning of

agriculture

Adapted from Steffen et al. 2004; ice core data from Petit et al. 1999

The relative stability of the Holocene

Aboriginesarrive inAustralia

Beginningof

agriculture

Great Asian,European, African,

Americancivilisations

Human Development andEarth System Dynamics

Source: GRIP ice core data (Greenland)and S. Oppenheimer, ”Out of Eden”, 2004

First migration offully modern humans

out of Africa

Migrations from South Asiato Europe

Holocene

The IPCC Assessments

The GreatAcceleration

• Population• Economic Growth• Freshwater use• Energy use• Urbanization• Globalization• Transport• Communication

The GreatAcceleration

• Population• Economic Growth• Freshwater use• Energy use• Urbanization• Globalization• Transport• Communication

Steffen et al. 2015

• Greenhouse gases• Ozone depletion• Climate• Marine ecosystems• Coastal zone• Nitrogen cycle• Tropical forests• Land systems• Biosphere integrity

• Greenhouse gases• Ozone depletion• Climate• Marine ecosystems• Coastal zone• Nitrogen cycle• Tropical forests• Land systems• Biosphere integrity

Global Impact

Steffen et al. 2015

Equity Issues

• Population• Economic growth• Fertilizer use• Urbanization• Globalization• Transport • Communication

Equity Issues

• Population• Economic growth• Fertilizer use• Urbanization• Globalization• Transport • Communication

Steffen et al. 2015

Source: Moran et al., Ecological Economics, 64, 470-474, 2008

The dilemma of the Great Acceleration

Human well‐being

Global Impact

Characterising Human Well‐being

Lessons from the Past

“…if we focus on other features of the past than humanity’s progress, we might find a human history marked by crises, regime shifts, disasters, and constantly changing patterns of adjustment to limits and confines. Indeed, this now emerges as a new historical meta-narrative, linking humanity’s creative past with its destructive consequences and nature-culture interplay…”

Sverker Sörlin & Paul Warde 2007

On the techno-scientific approach to progress

Homer‐Dixon et al. 2015

Synchronous Failure: Architecture of Global Crises

The Food‐Energy Crisis

Capitalism drivesinequality in wealth

Capitalism drivesclimate disruption

We're only here for a short amount of time to do what we'vebeen put here to do, which is to look after the country. We're only a tool in the cycle of things. …(we) go out intothe world and help keep the balance of nature. It's a bigcycle of living with the land, and then eventually going back to it....

Vilma Webb, Noongar People, AustralianAborigines, from: 'Elders: Wisdom from Australia's Indigenous Leaders’

© S

ebas

tião

Salg

ado

…where on Earth are we going?

The Anthropocene…