Beyond cobenefits The value of tropical forests to
Beyond co-benefits: The value of tropical forests to climate change mitigation and adaptation Mandar Trivedi Global Canopy Programme m. trivedi@globalcanopy. org
20% of global C emissions BAU deforestation to 2012 equal to all air travel emissions from Wright bros to 2025
(scientific? ) narratives of tropical forests Existence value
(scientific? ) narratives of tropical forests Mitigation value
(scientific? ) narratives of tropical forests Utility value(s) Rainfall generation Carbon storage Poverty alleviation Biodiversity maintenance … Et cetera ad infinitum?
Ecosystem services • Cultural (e. g. traditional values) • Local • Provisioning (e. g. food, freshwater) • Regional • Supporting (e. g. nutrient cycling) • Regulating (e. g. climate, disease) • Global
Local • People rely on cultural/provisioning ES: • 60 million indigenous people almost wholly dependent on forests • >1. 4 bn of the world’s poorest people rely on forests for some part of their livelihoods/food security • Often rely on biodiversity during climatic shocks • Forests help to provide clean water ADAPTATION
Local-regional • Supporting/regulating ES • Canopy: local cooling effect through evaporation • Roots: prevention of erosion/mudslides/flooding Flooding costs about $100 bn/year Flood frequency linked to deforestation ADAPTATION
Regional-global • Hydrology Water vapour from oceans Rain Some rain water recycled Drainage to rivers Evaporation and cooling effect Extraction of soil water by roots
Marengo et al, 2005 Plata Basin: $1 trillion
Global • Carbon sequestration – Tropical forests absorbing and storing about 1 billion t. C/year – Approximate MITIGATION value of $43 billion/year – Causes? • Forest responses to changing atmosphere
The forests are increasing in biomass, apparently at a rate related to soil fertility n = 95 Increasing fertility
The forests appear to be accelerating in growth and death over time Biomass growth rate, t / ha / year 12 Amazon+95% CI 11 Amazon-95% CI 10 9 8 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 Year Phillips et al. (2004), Patterns and process in Amazon tree turnover 1975 -2000, Philosophical Transactions of the Royal Society
Compositional changes
1980 1990 2000 Phillips et al, 2002, Increasing dominance of lianas in Amazonian forests, Nature
Regional – global: Latest model findings…. • Deforestation impacts on rainfall: – Roni (Duke University) • Deforestation versus Die-back: – Yadvinder Malhi (Oxford University) – Richard Betts (UK Hadley Centre)
Deforestation versus Die-back (Yadvinder Malhi)
1. Die-back
The climate-forest system of Amazonia may have two stable states Oyama and Nobre, 2003
Atmospheric carbon dioxide: 1000 AD to 2000 AD Source: Intergovernmental Panel on Climate Change
IPCC Fourth Assessment Report
Probability of rainfall reductions by 2050 under mid-range (A 1 B) emissions scenarios Malhi et al Climate change, deforestation, and the fate of the Amazon, Science, in press
Future climate impacts • Die-back is an extreme scenario – most models imply drying in the eastern Amazon over the 21 st century, but NOT savannisation
2. Deforestation impacts
An insight from the 2005 Amazonia drought
The climate fate of the Amazon forest depends on sea surface temperatures inthe tropical Atlantic Sea Surface Temperature Anomalies: Source: Brazilian Centre for Weather and Climate Prediction
Soil water anomalies in the 2005 drought Aragão, et al, Spatial fingerprints of recent Amazonian droughts, Geophysical Research Letters. (2007)
Fire anomalies during the 2005 Amazonian drought n tio ta es r o ef fd co r A Aragão, et al, Spatial fingerprints of recent Amazonian droughts, Geophysical Research Letters. (2007)
Positive vegetation feedback Forest Fire Susceptibility Logging Nepstad, Carvalho, Barros et al. 2001 Forest Ecology and Management
Deforestation vs. die-back • There is a non-negligible (but poorly quantified) probability of significant drying of Amazonia over the 21 st century • Intact lowland forests seem fairly resilient to drying , but forest and fragmentation clearance leaves remaining forests vulnerable • Deforestation greater than 30 -40% may tip the region into an irreversibly drier climate • Maintaining greater 60 -70% forest cover may maintain the resilience of Amazonia to climate change
Omissions and emissions (Richard Betts)
SRES land use scenarios may underestimate deforestation A 2 scenario, 2050 Amazonia deforested by 435, 000 km 2 Soares-Filho (2006), BAU 2050 Amazonia deforested by 2, 067, 000 km 2 Soares-Filho (2006), “Governance” 2050 Amazonia deforested by 913, 000 km 2
Afforestation / deforestation also affects climate through physical properties of land surface Net effect of carbon uptake and surface albedo change (Betts, Nature, 2000) Impact of Soares-Filho deforestation projection on precipitation (Carreia et al 2006)
Impacts of climate change on tropical forests are highly uncertain Forest cover change by 2100, standard Had. CM 3 LC Forest cover change by 2100, Had. CM 3 C perturbed-physics ensemble member Booth (in preparation)
Even in extreme “Amazon die-back” scenario, direct deforestation is projected to impact Forest cover change, standard Had. CM 3 LC + Soares-Filho BAU sooner deforestation 2020 2050
CO 2 airborne fraction and carbon sinks
Conclusions • In Amazonia, bottom-up scenarios project much faster rates of deforestation than the most extreme top-down SRES scenario • Climate-driven “Amazon dieback” remains plausible but uncertain • Even in extreme case, direct deforestation is projected to impact Amazonia before climatedriven dieback • Removal of the forest carbon sink could contribute further to the CO 2 rise by increasing the airborne fraction
Summary • Forest conservation has moved from ‘value-driven’ to ‘carbon mitigation’. The new frontier is to view the role of forests as a ‘global climate utility’. • Climate models are uncertain and need more work • Die-back is long-term possibility but deforestation is a near -term threat • IPCC Models do not account adequately for deforestation impacts with consequences for our understanding of: – Rainfall – Carbon dynamics • IPCC 5 th Assessment should look in more detail at deforestation impacts on carbon and climate in general. The Report’s structure is now being negotiated.
Thanks! • • Richard Betts (UK MO Hadley Centre) Yadvinder Malhi (Univ. of Oxford) Niki Mardas & Andrew Mitchell (GCP) Paul Holland, Anna Creed, Simon Rietbergen (Prince’s Rainforests Project) • Stavros Papageorgiou (Univ. of Oxford) • Dominic Moran (Scottish Agricultural College)
REDD offers an opportunity to halt carbon emissions from deforestation
Not just sticks of carbon…
The interface between Life and the Atmosphere
Trends in mean temperature in tropical rainforest regions 1975 -1998 Malhi and Wright (2004), Philosophical Transactions of the Royal Society Spatial patterns and recent trends in the climate of tropical rainforest regions
- Slides: 45