Feeding A Hot And Hungry Planet Tim Searchinger

FEEDING A HOT AND HUNGRY PLANET
Tim Searchinger
(Princeton University, German Marshall Fund of the U.S.
tsearchi@princeton.edu
Courtesy IIASA

Ag’s Contribution to World Greenhouse Gases ~ 30%
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
(IPCC 2007; Bellarby2008 , in CO2 eq.)

- 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

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 . . .
Biofuels & Greenhouse Gases
Land grows plants (carbon) anyway
* forest
* food
Only ADDITIONAL plant growth helps

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 ScenariosPredicted Emissions from Land Use Change Gigatons C

Can We Avoid Land Use Change for Food?
Croplands
Agriculture occupies 35% of ice free surface
Grazing lands
Foley J A et al. PNAS 2007;104:12585-12586
©2007 by National Academy of Sciences

No-policy scenario
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.

Impacts on Yields of Climate Change Itself
Change in average maximum temperature ( oC), 2000–2050
top is CSIRO; bottom is NCAR
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
also:
* Much food waste
* Biotechnology
Livestock intensification opportunities
FAO’s latest estimate ~120 million hectares additional cropland by 2050
Courtesy of Pedro Sanchez

Natural Forest (Melillo, Gurgel, et al. 2008)
Natural Forest

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
Adapted from Davidson, Nature Geoscience2:659-662 (2009)

Steinfeld et al. 2007, Livestock’s Long Shadow (FAO)

World Grazing Land
Haberl et al., PNAS 104:12942-12947
Contrast FAO Grazing Land NPP World - 1047

Rangeland Thoughts
Possible Pursuit: Productivity enhancement plus forest regeneration

Better UnderstandingChallenges of Lifecycle Analysis for Livestock(source TheunVellinga, 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 Supergranules
IFDC
17-33% yield gains, decreases urea by 33%

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

Feeding A Hot And Hungry Planet Tim Searchinger

by aimeew on Apr 06, 2010

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