Global Greenhouse Gas Mitigation Potential in Agriculture

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Global Greenhouse Gas Mitigation Potential in
Agriculture

• Pete Smith

Royal Society-Wolfson Professor of Soils Global
Change, FIBiol., FRSE Institute of Biological
Environmental Sciences, School of Biological
Sciences, University of Aberdeen, Scotland,
UK E-mail pete.smith_at_abdn.ac.uk
Climate Change, Global Risks, Challenges and
Decisions, Copenhagen, 10-12th March 2009
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Co-authors of the work

• Daniel Martino, Zucong Cai, Daniel Gwary, Henry
  Janzen, Pushpam Kumar, Bruce McCarl, Stephen
  Ogle, Frank OMara, Charles Rice, Steve Rose, Bob
  Scholes, Oleg Sirotenko, Mark Howden, Tim
  McAllister, Genxing Pan, Vladimir Romanenkov, Uwe
  Schneider, Sirintornthep Towprayoon Martin
  Wattenbach

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Method

• Database of over 200 experiments to derive
  per-area / per-animal mitigation efficiencies for
  gt60 agricultural mitigation options, for four
  climate zones for CO2, CH4 and N2O
• Mean estimates and low and high 95 CI values
  derived from mixed effects modelling
• Applied to appropriate agricultural (crop, grass,
  livestock) areas / numbers in each climate zone
  in each region

Smith et al. (2007, 2008)
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Ogle et al. (2003)
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Per-area / per-animal mitigation potential
For 14 practices, for 4 climate zones, for CO2,
N2O CH4, estimates for mean and /- 95CI
Smith et al. (2008)
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Soil C sequestration rates for cool dry climate
Data from Smith et al. (2008)
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Soil C sequestration rates in different climates
Cool
Warm
Dry
Moist
Data from Smith et al. (2008)
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IPCC AR4 Agricultural GHG Mitigation
FAO AEZ Database (e.g. showing land cover)
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IPCC AR4 Agricultural GHG Mitigation
FAO AEZ Database (e.g. showing thermal climate)
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IPCC AR4 Agricultural GHG Mitigation
FAO AEZ Database (e.g. showing production
constraints)
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Global mitigation potential in agriculture
Smith et al. (2008)
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High and low estimates of the mitigation
potential in each region
Smith et al. (2007)
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Effect of C price on implementation
Smith et al. (2007)
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Global mitigation potential in agriculture (Mt
CO2-eq. yr-1)
Smith et al. (2007a)
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Additional mitigation from agriculture

• Feed-stocks for bio-energy (residues, dung and
  dedicated energy crops).
• The economic mitigation potential for
  agricultural bio-energy in 2030 is estimated to
  be 70-1260, 560-2320 and 2720 Mt CO2-eq. yr-1 at
  prices up to 20, 50 and above 100 USD t
  CO2-eq.-1, respectively (5-90 of all other
  measures together).
• Additional mitigation of 770 Mt CO2-eq. yr-1
  could be achieved by 2030 by improved energy
  efficiency in agriculture

Smith et al. (2007a)
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How important is this mitigation potential?

• Even at 100 USD t CO2-eq.-1, mitigation potential
  is 3100-3300 Mt CO2-eq. yr-1
• This is equivalent to less than 1000 Mt C yr-1 or
  lt1 Pg per year
• Atmospheric CO2-C is increasing at a rate of 3.2
  Pg C yr-1 so soil C sequestration can mitigate
  about 30 of this increase and less than 15 of
  annual 1990s fossil fuel C emissions
• So is this significant?

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What are our targets?

• The EU has an 8 GHG emission reduction target
  under the Kyoto Protocol (compared to 1990)
• Longer term target to avoid dangerous climate
  change 2ºC temperature increase) 80
  reduction in GHG emissions by 2050 (generally
  accepted need already in law in UK Scotland)
• So mitigation potential of 15 of total GHG
  emissions is above Kyoto target (in only one
  sector), and forms a significant chunk of the 80
  GHG emission reduction target for 2050
• Answer Yes it is very significant

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Global economic mitigation potential for
different sectors at different carbon prices
IPCC WGIII (2007)
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Conclusions

• Agriculture has a significant role to play in
  climate mitigation
• Agriculture is cost competitive with mitigation
  options in other sectors
• Bio-energy crops and improved energy efficiency
  in agriculture can contribute to further climate
  mitigation, but the savings are usually counted
  in other sectors
• Agricultural mitigation should be part of a
  portfolio of mitigation measures to reduce
  emissions / increase sinks whilst new, low carbon
  energy technologies are developed.

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Thank you for your attention