Feeding A Hot And Hungry Planet Tim Searchinger
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Courtesy IIASA
FEEDING A HOT AND HUNGRY PLANETTim Searchinger
(Princeton University, German Marshall Fund of the U.S.tsearchi@princeton.edu
Ag’s Contribution to World Greenhouse Gases ~ 30%
(IPCC 2007; Bellarby 2008 , in CO2 eq.)
• Nitrous oxide – fertilizer, livestock deposits, biomass burning
• Methane – livestock (enteric), cows, rice, manure, biomass burning
• Energy – farm machinery, fertilizer, irrigation pumps
• 13 million hectares/yr gross deforestation
• N20 and NH4 to grow 60% by 2030
Non-Ag33.5 Gt
69%
Ag Land Expansion
8.5Gt17%
CO2 from Energy
Use1 Gt2% N2O and
NH46 Gt12%
2004
49 Gt Total
- 16% of world malnourished- 1/3 of children in developing world stunted- 30 million babies born impaired due to lack of natal nutrition - 5 million children die annually from causes related to lack of nutrition
19501952
19541956
19581960
19621964
19661968
19701972
19741976
19781980
19821984
19861988
19901992
19941996
19982000
20022004
20062008
$0
$2
$4
$6
$8
$10
$12
$14 Trends in Cereal Crop Prices, United States Season Average
BarleyCornOatsSorghumWheat
Seas
on a
vera
ge p
rice
, $/b
ushe
l 2000 Constant $
Source: USDA, NASS
Undernourished People and Recent Changes
Source: FAO. 2009. The State of Food Insecurity In the World, 2008
Agriculture Mitigation Potential at $100/t(IPPC 2007 Mitigation Report)
The Challenge of Soil Carbon Gains
• No Till– Depth
• Baker et al., Agriculture Ecosystems and Env. 118:1-5 (2007); • Blanco-Canqui & Lal, SSSAJ 72:693-701 (2008)
– Nitrous Oxide• Africa• Are we actually losing soil carbon?
– UK, Midwest– New Zealand
Biochar?
Conventional approach But . . . Land grows plants
(carbon) anyway* forest* food
Only ADDITIONAL plant growth helps
Biofuels & Greenhouse Gases
Large Bioenergy Potential Studies
• Most potential arable land – IPCC 2007 chapter 8 - 1.3billion hectares and/or
• All forest growth in excess of harvest (Smeets 2008)and/or
• All “abandoned” cropland (Hoodwijk (2004) and/or
• Hundreds of millions of hectares of “grazing” or “other” land – savannah (Fischer 2001; Smith 2007)
Recounts existing forest, forest re-growth, net terrestrial carbon sink, land counted for grazing
Unused Cropland is Mostly Wetter Savannah, Woodlots and Forest in Latin
America and Africa
Other Uses of Land?
• More cropland and pasture for food –200-500 million hectares by 2050
• Terrestrial carbon sink – 9.5 GT CO2/yr• Avoided deforestation potential – 9 Gt/year• Afforestation mitigation potential – 4 Gt/year• Restore peatlands – 1.3 gigatons/year
All from IPCC 2007 Mitigation Report, chapters 8 & 9
IPCC Baselines – Mission Accomplished? IPCC SRES Scenarios
Predicted Emissions from Land Use Change Gigatons C
Year B-1 B-2
2020 2.2 0
2050 -0.4 -0.2
Foley J A et al. PNAS 2007;104:12585-12586
©2007 by National Academy of Sciences
Croplands
Grazing lands
Can We Avoid Land Use Change for Food?
Agriculture occupies 35% of ice free surface
19651967
19691971
19731975
19771979
19811983
19851987
19891991
19931995
19971999
20012003
20050
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
World Cereal Yield Growth 1965-2006
5 year average percent change in cereal WorldLinear (5 year average percent change in cereal World)5 year average percent change in Population WorldLinear (5 year average percent change in Population World)
5 ye
ar a
vera
ge a
nnua
l cha
nge
, per
cent
Carbon Dioxide Emissions – Reilly (MIT) – Impact of Ozone
Note: Emissions from land use change are those from projected changes. Continuing uptake from forest regrowth from pre-2000 land use change and changed uptake (due to CO2/climate) on undisturbed land is not shown.
No-policy scenario
Reference
-100
102030405060708090
2010 2040 2070 2100Year
CO2
emis
sion
s (b
mt)
Land All other Total
Change in average maximum temperature ( oC), 2000–2050top is CSIRO; bottom is NCAR
Impacts on Yields of Climate Change Itself
Nelson et al., Climate Change Impact on Agriculture (IFPRI 2009)
With no crop fertilization effect , by 2050:–Rice yields decline by 14 – 18% in developing countries- Irrigated wheat declines 28-34%
Areas of Water Stress (IIASA)
Optimism: Yields Gaps
Courtesy of Pedro Sanchez
also:* Much food waste* Biotechnology•Livestock intensification opportunities
•FAO’s latest estimate ~120 million hectares additional cropland by 2050
Natural Forest
Natural Forest (Melillo, Gurgel, et al. 2008)
Natural Forest (“Deforestation” Scenario)
Natural Forest
Land Lessons
• Land is limited
• MORE CARBON NOT DIFFERENT CARBON
• Understand land/input tradeoffs
Important question: where isthe underutilized “other” land
• Carbon content• Outputs• Biodiversity• Ownership• Barriers to use
Peatland Restoration – 1.3 Gt/y (IPCC 2007 Mitigation)
70% of rice straw in Punjab burned Punia, Current Science 94:1185-1190 (2008)
Predicted 2000-2010 Pasture & Cropland Expansion in Latin America
Wassenaar et al., Global Env. Change 17:86-104 (2007)
Two thirds of net agricultural expansion is pasture
Sources of Nitrous Oxide
EPA 2006 Davidson 2009 Crutzen
Manure & Fertilizer
4.4 soils0.4 manure management
2.2 Fertilizer2.8 Manure
4.3-5.8
Adapted from Davidson, Nature Geoscience 2:659-662 (2009)
Role of Livestock in Methane and Nitrous Oxide Emissions
Gas Source Mainly Mainly Percentagerelated to related to contributionextensive intensive to totalsystems systems animal food
(109 tonnes CO2 eq.)
(109 tonnes CO2 eq.) GHG emissions
CH4 Total anthropogenic CO2 emissions 5.9
Total from livestock activities 2.2
enteric fermentation 1.6 0.2 25
manure management 0.17 0.2 5.2
N2O Total anthropogenic CO2 emissions 3.4 Total from livestock activities 2.2
N fertilizer application ~ 0.1 1.4
indirect fertilizer emission ~ 0.1 1.4
leguminous feed cropping ~ 0.2 2.8manure management 0.24 0.09 4.6manure application/deposition 0.67 0.17 12indirect manure emission ~ 0.48 ~ 0.14 8.7
Steinfeld et al. 2007, Livestock’s Long Shadow (FAO)
Land Use Original Net Primary Productivity
Actual Net Primary Productivity
Human Appropriated Percentage
Cropland 611 397 83.5%
Grazing Land 486 433 19.4%
Forestry 720 720 6.6%
Haberl et al., PNAS 104:12942-12947
World Grazing Land
Contrast FAO Grazing Land NPP World - 1047
Rangeland Thoughts
• Possible Pursuit: Productivity enhancement plus forest regeneration
Better UnderstandingChallenges of Lifecycle Analysis for Livestock
(source Theun Vellinga, Wageninen University)
• Reasonable data available– Kilograms of meat, milk, slaughtered animals– Total numbers of animals– Total fertilizer input on country level
• No systematic data available– herd demography– feed use– pasture quality– feed production – and manure management
Doberman, Cassman, Ser. C Life Sciences 48:745-758 (2005)
Deep Placed Urea SupergranulesIFDC
17-33% yield gains, decreases urea by 33%
Comparison of USG with Urea using Farmer's Practice
N Applied (kg N ha-1)
0 20 40 60 80 100 120 140 160 180
Ric
e G
rain
Yie
ld (
kg h
a-1)
1200
16002000
24002800
32003600
400044004800
52005600
60006400
68007200
760080008400
Urea (IFDC, 2000-5) USG (IFDC, 2000-5)Urea (IRRI, Bangladesh)USG (IRRI, Bangladesh)
Technological Policy Development Basic research
Rice High yielding upland or drier rice varieties
Technical and economic barriers to mid-season drainage outside of China
Cheap water management measures
•Measuring real NH4 and N20 effects; • Study controlling microbiology
Crop fertilization
*New fertilizer technologies;*Improved nitrification inhibitors; *Improved crop nitrogen use efficiencies
*Assessing existing fertilizer type use and trends in many areas;*Assessing barriers to adopting newer practices
*Widespread farmer testing of reduced or split season fertilizer application; *Cheaper tests; *New harvesting technologies for tree inter-cropping;*Testing new fertilizers
•Factors that control N availability•Assessing N20 effects in the field; *Tools for assessing land/input tradeoffs
Technological Policy Development Basic research
Livestock VaccineFood additivesNitrification inhibitorsManure reprocessing technologies
*Better understanding of livestock systems*Technological and economic opportunities for improved pasture efficiency
Livestock breeds;Aquaculture development;Improved digesters
Basic understanding of livestock systems, forage quality
Food waste Careful assessments of true storage obstacles
Factors that lead to food waste in developed countries
and now a brief advertisement . . .
Final Thoughts• “All” is beautiful
– Seek copper bullets– Don’t forget the “D” of R&D
• Practical/strategic approach– Coordinating teams– Scrutinize the teams
• Constantly question & improve numbers & make real field assessments
• Mix technology, policy, development & basic research• Give rangeland the respect it deserves• Immediate Policies That Can’t Wait
– Integrate REDD/food production– Develop NAMA guidance
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