Carlos A Nobre, Han Dolman, Gilvan Sampaio, Luiz Salazar,

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The Possibility of Amazon Forest Savannization
and Die-Back
Carlos A Nobre, Han Dolman, Gilvan Sampaio, Luiz
Salazar, Marcos Oyama, José Marengo Centro de
Ciência do Sistema Terrestre Instituto Nacional
de Pesquisas Espaciais INPE
Workshop Sharing experiences in the design and
implementation of climate change adaptation
measures
Lima, Peru 23 January 2009
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Risk Analysis of Amazon Forest Die-back

• Science Program at the
• World Bank Latin America Region
• Walter Vergara, Co-ordinator

Participating Institutions INPE, Brazil MRI,
Japan Exeter University, UK PIK, Germany
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Objective of Amazon Dieback Risk Analysis

• Assist in understanding the risk, process and
  dynamics of Amazon dieback and its implications.
• Support the analysis of long-term options that
  would be required to maintain the integrity of
  the basin.
• Delivery date June 2009

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Does vegetation matter for the Earth System ?

• The impacts of human activity on the Amazon
  rainforest could result in the collapse of large
  portions of the rainforest and significant loss
  of biodiversity within 30 to 50 years.
• A comparison is made with similar events in the
  Saharan ecosystem, which was once a region of
  richer vegetation, before its abrupt collapse
  about 6000 years ago

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Vegetation partitions net radiation into more
latent and less sensible heat
(figure taken from Kabat et al. Vegetation,
Water, Humans, and the Climate, IGBP BAHC)
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Remove vegetation from the continents ? large
changes will happen in the water cycle
Kleidon et al. (2000)
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Biomes of tropical south America and
precipitation seasonality
Tropical Forest-Savanna Boundary
Number of consecutive months with less than 50
mm rainfall
Biomes of Brazil
Tropical Forest
Shrubland
Savanna
Annual Rainfall
The importance of rainfall seasonality (short dry
season) for maintaining tropical forests all over
Amazonia
Sombroek 2001, Ambio
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Evapotranspiration seasonality in the Amazon
tropical forest and savanna Source Rocha (2004)
Forest
Latent Heat flux (W m-2)
mm day-1
Savanna
Forest
Net Radiation (W m-2)
Savanna
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The Hypothesis of Amazonian Savannization

• Nobre et al. (1991) proposed that a
  post-deforestation climate in Southern Amazonia
  would be warmer, drier and with longer dry
  season, typical of the climate envelope of the
  tropical savanna (Cerrado) domain of Central
  South America.
• Savannization in this context is a statement on
  regional climate change and not intended to
  describe complex ecological processes of
  vegetation substitution.

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Modeling Deforestation and Biogeography in
Amazonia
Current Biomes
Post-deforestation
Nobre et al. 1991, J. Climate
1 Tropical Forest 6 Savanna
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Is the current Climate-Biome equilibrium in
Amazonia the only stable equilibrium possible?
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Two Biome-Climate Equilibrium States found for
South America
Current potential vegetation
-- current state (a) -- second state (b)
Soil Moisture
Second State Results of CPTEC-DBM Initial
Conditions desert
Rainfall anomalies
Source Oyama and Nobre, 2003
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Can global warming, deforestation, increased
droughts and forest fires tip the current
biome-climate equilibrium in the Amazon?
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The ecosystems of Amazonia are subjected to a
suite of environmental drivers of change
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Tipping Points of the Climate System

• Need to advance our understanding of critical
  tipping-points and hot-spot systems at risk, such
  as the Amazon.
• The picture remains relatively scanty, with
  limited system-wide mapping of thresholds,
  cross-scale interactions and how system
  components reinforce each other amplifying the
  risk of crossing thresholds.

Externally driven equilibrium change
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• Question Is there a tipping point of
  deforestation or global warming to induce
  abrupt changes to the second biome-climate
  stable equilibrium?

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In 2007, total deforested area (clear-cutting) is
700,000 km2 in Brazilian Amazonia (18)
DEFORESTATION
GLOBAL WARMING
Anthropoenic and Natural Drivers of Environmental
Change in Amazonia
DROUGHTS
FIRE
Source Greenpeace/Daniel Beltra
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I - LAND USE AND COVER CHANGE
DEFORESTATION AND BURNING AROUND THE XINGU
INDIGENOUS PARK, MATO GROSSO STATE, BRAZIL,
2004. Source Tropical deforestation and climate
change / edited by Paulo Moutinho and
Stephan Schwartzman. -- IPAM - Instituto de
Pesquisa Ambiental da Amazônia, 2005.
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PROJECTED LAND COVER CHANGE SCENARIOS
Source Soares-Filho et al., 2006 - Amazon
Scenarios Project, LBA
Sampaio et al., 2007
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Threshold of Deforestation at 40!
Controle
Pastagem
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II GLOBAL WARMING
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What are the likely biome changes in Tropical
South America due to Global Warming scenarios of
climate change?
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Cenários Climáticos globais para América do Sul
Projeções de anomalias de temperatura (mm/dia)
para América do Sul para o período de 2090-2099
(Cenário A2) em relação ao período base de
1961-1990 para 15 diferentes modelos climáticos
globais disponíveis através do IPCC.
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Cenários Climáticos globais para América do Sul
Projeções de anomalias de precipitação (mm/dia)
para América do Sul para o período de 2090-2099
(Cenário A2) em relação ao período base de
1961-1990 para 15 diferentes modelos climáticos
globais disponíveis através do IPCC.
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Climate Change Scenarios for Amazonia
Results from 15 AOGCMs for the SRES A2 and B1
emissions scenarios, prepared for the IPCC/AR4.
Models BCCR-BCM2.0, CCSM3, CGCM3.1(T47),
CNRM-CM3, CSIRO-MK3, ECHAM5, GFDL-CM2,
GFDL-CM2.1, GISS-ER, INM-CM3, IPSL-CM4, MIROC3.2
(MEDRES), MRI-CGCM2.3.2, UKMO-HADCM3, ECHO-G
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Climate Change Consequences on the Biome
distribution in tropical South America
Projected distribution of natural biomes in South
America for 2090-2099 from 15 AOGCMs for the A2
emissions scenarios, calculated by using
CPTEC-INPE PVM.
Salazar et al., 2007
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Climate Change Consequences on the Biome
distribution in tropical South America
2050-2059
2090-2099
2020-2029
Grid points where more than 75 of the models
used (gt 11 models) coincide as projecting the
future condition of the tropical forest and the
savanna in relation with the current potential
vegetation. The figure also shows the grid
points where a consensus amongst the models of
the future condition of the tropical forest was
not found. for the periods (a) 2020-2029, (b)
2050-2059 and (c) 2090-2099 for B1 GHG emissions
scenario and (d), (e) and (f) similarly for A2
GHG emissions scenario.
SRES B1
SRES B1
SRES B1
SRES A2
SRES A2
SRES A2
Salazar et al., 2007 GRL (accepted)
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III - CLIMATE EXTREMES
The impact of droughts
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Are hydrological extremes becoming more frequent?
The 2005 Western Amazon drought one of the the
most intense drought of the last 100
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Anomalous enhancement of Hadley Cell-type
circulation in September 2005
Descending motion over Amazonia Inhibiting
cloud and rain formation
Tropical North Atlantic warmer waters
Amazonia
Cox et al., 2008, Nature This type of drought
induced by latitudinal SST gradients in the
Tropical Atlantic will become frequent in the
future
Cortesia Jacy Saraira - SIPAM
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Use of the LPJ Vegetation Modelto study the
impact of droughts on the Amazonian carbon cycle
e.g. Stich et al., 2003
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Rainforest C-content collapses after a series
of drier years but recovers when climate gets
wet again
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High moisture
High T
hysteresis indicates effect of soil moisture
memory
Wet state
Dry state
Low moisture
Low T
Two stable states correspond to wet tropical
humid and to dry tropical climates with tipping
point of surface evaporation at 3.5 mm/day
(current evaporation tropical rainforest 4-4.2
mm/day)
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In 2007, total deforested area (clear-cutting) is
700,000 km2 in Brazilian Amazonia (18)

DEFORESTATION
GLOBAL WARMING
Anthropoenic and Natural Drivers of Environmental
Change in Amazonia
What are the synergistic impact of global
warming deforestation?
Source Greenpeace/Daniel Beltra
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Climate Change Scenarios Projected
Deforestation Scenarios
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Climate Change Scenarios from 15 AOGCMs for the
SRES A2 and B1 emissions scenarios, prepared for
the IPCC/AR4.Models BCCR-BCM2.0, CCSM3,
CGCM3.1(T47), CNRM-CM3, CSIRO-MK3, ECHAM5,
GFDL-CM2, GFDL-CM2.1, GISS-ER, INM-CM3, IPSL-CM4,
MIROC3.2 (MEDRES), MRI-CGCM2.3.2, UKMO-HADCM3,
ECHO-G
60
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Projected distribution of natural biomes in South
America for 2050 from 15 AOGCMs for the B1
emissions scenario projected land cover
scenario with 40 of deforestation area for the
Amazon
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Projected distribution of natural biomes in South
America for 2100 from 15 AOGCMs for the A2
emissions scenario projected land cover
scenario with 60 of deforestation area for the
Amazon
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Remaining Forest Area in Tropical South America
() due to The combined effect of Global Warming
and Deforestation
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Remaining Forest Area in Tropical South America
(km2) due to The combined effect of Global
Warming and Deforestation
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Total Area of Savanna in Tropical South America
() due to The combined effect of Global Warming
and Deforestation
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Total Area of Savanna in Tropical South America
(km) due to The combined effect of Global Warming
and Deforestation
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Main Conclusions on the future of biome
distribution in Amazonia in face of land cover
and climate changesI

• The synergistic combination of regional climate
  changes caused by both global warming and land
  cover change over the next several decades,
  exacerbated by increased drought and forest fire
  frequency, could tip the biome-climate state to a
  new stable equilibrium with savannization of
  parts of Amazonia and catastrophic species
  losses.

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Main Conclusions on the future of biome
distribution in Amazonia in face of land cover
and climate changesII

• CO2 fertilization effects could increase forest
  resilience, but with less efficiency with
  continued warming and deforestation.

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Main Conclusions on the future of biome
distribution in Amazonia in face of land cover
and climate changesIII

• Tentatively, we can say that thresholds for the
  maintenance of the rainforests are less than 4 C
  of global warming and less than 40 of total
  deforestation.

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MUCHAS GRACIAS!
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THANK YOU!