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Cited by 1,128Agriculture Sustainability and Environmental ImpactClimate change impacts on agricultureClimate Change Policy and Economics

Greenhouse gas mitigation by agricultural intensification

Open access
Burney, Jennifer A., Davis, Steven J., Lobell, David B.·2010·Proceedings of the National Academy of Sciences
DOI 10.1073/pnas.0914216107PMC PMC2900707
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Abstract

As efforts to mitigate climate change increase, there is a need to identify cost-effective ways to avoid emissions of greenhouse gases (GHGs). Agriculture is rightly recognized as a source of considerable emissions, with concomitant opportunities for mitigation. Although future agricultural productivity is critical, as it will shape emissions from conversion of native landscapes to food and biofuel crops, investment in agricultural research is rarely mentioned as a mitigation strategy. Here we estimate the net effect on GHG emissions of historical agricultural intensification between 1961 and 2005. We find that while emissions from factors such as fertilizer production and application have increased, the net effect of higher yields has avoided emissions of up to 161 gigatons of carbon (GtC) (590 GtCO 2 e) since 1961. We estimate that each dollar invested in agricultural yields has resulted in 68 fewer kgC (249 kgCO 2 e) emissions relative to 1961 technology ($14.74/tC, or ∼$4/tCO 2 e), avoiding 3.6 GtC (13.1 GtCO 2 e) per year. Our analysis indicates that investment in yield improvements compares favorably with other commonly proposed mitigation strategies. Further yield improvements should therefore be prominent among efforts to reduce future GHG emissions.

AI snapshot

Written from the paper’s full text.

TL;DR

The paper estimates that historical agricultural intensification from 1961 to 2005 avoided large greenhouse gas emissions by sparing land conversion, with an upper estimate of 161 GtC (590 GtCO2e) and a lower-bound estimate of 86.5 GtC. It concludes that investment in yield improvements compares favorably with other mitigation strategies and should be prominent in efforts to reduce future emissions.

Key findings

  • Yield gains since 1961 avoided 161 GtC (+104.2/−41.9 GtC) in the AW1 scenario, averaging 3.6 GtC/yr (+2.3/−0.9 GtC/yr), equal to 34% of the 478 GtC emitted by humans between 1850 and 2005. The lower-bound AW2 scenario avoided 86.5 GtC (±24.7 GtC), averaging 1.9 GtC/yr (±0.5 GtC/yr), or 18% of that total.
  • AW1 would have required an additional 1,761 Mha of cropland (1,514 Mha more than the real world); AW2 would have required an additional 1,111 Mha (864 Mha more than the real world). Land conversion dominated emissions, with a global average of 105 ±21 tC/ha lost in conversion of land to cropland.
  • Each dollar invested in agricultural yields resulted in 68 fewer kgC (249 kgCO2e) emissions relative to 1961 technology, at $14.74/tC (∼$4/tCO2e) in AW1 and $27.43/tC in AW2 under the refined estimate; simple estimates were $7.16/tC and $13.32/tC. This compares favorably with other options available at <$73/tC: buildings (1.49 GtC/yr), energy supply (0.49 GtC/yr), transportation (0.46 GtC/yr), and industry (0.30 GtC/yr).
  • Context: between 1961 and 2005 population rose 111% (3.08 to 6.51 billion), crop production rose 162% (1.8 to 4.8 billion tons), cropland grew 27% (960 to 1,208 Mha), and total crop yield increased 135% (1.84 to 3.96 t/ha). In 2005 agricultural production accounted for 1.4–1.7 GtC emissions (10–12% of anthropogenic GHG emissions), with land use change adding 1.5 GtC.

Methods

  • The authors calculated agricultural GHG emissions for 1961–2005 and two counterfactual “alternative world” scenarios: AW1 held 1961 yields and fertilizer application rates while meeting real-world production and living standards; AW2 maintained 1961 per capita production using population projections based on 1950–1955 fertility and mortality rates.
  • Emissions included N2O from agricultural soils, CH4 from rice cultivation, carbon released from biomass and soil during conversion of forest, shrub, and grassland to cropland, and N2O, CH4, and CO2 from production and use of nitrogenous, phosphate, and potash fertilizers. The analysis used FAO production and yield data, IPCC Tier 1 guidelines, GREET emissions factors, biome carbon values, and cropland-only accounting.
  • Cost-effectiveness was assessed using public and private agricultural research spending from 1961 to 2005, with assumptions about the fraction of research relevant to yield improvements and the share of productivity growth attributable to agricultural R&D.

Limitations

  • Stated: the counterfactual scenarios are not dynamic; AW1 assumes demand for agricultural products would have been identical without yield improvements, ignoring food-price effects (real prices fell by ∼40% between 1965 and 2000), and AW2 is a lower bound with a more dire lower-bound scenario acknowledged.
  • Stated: the analysis excludes livestock, burning of agricultural residues, pesticides, fuel use, agricultural machinery, irrigation, transport, pastureland, and biofuels, and neglects projected increases in meat demand as per capita GDP grows; land carbon values carry ±20% uncertainty.
  • Evident: results depend on scenario assumptions and broad cost-effectiveness ranges, and the paper notes difficulty identifying hypothetical expansion regions and the portions of agricultural investment relevant to yield improvements.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1073/pnas.0914216107

Cites

52 of 52 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 45 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    Yield gains in agriculture since 1961 have avoided emissions of 86.5 GtC (±24.7 GtC) in the AW2 scenario.

    “yield gains in agriculture since 1961 have avoided emissions of 86.5 GtC (±24.7 GtC)”
    Quote in the paperSubstantial claim
  • Findingown data

    In the AW1 scenario, an additional 1,761 Mha of cropland would have been needed to achieve the same production levels since 1961 while holding yields and fertilizer intensities constant.

    “In the AW1 scenario, an additional 1,761 Mha of cropland (an area larger than Russia) would have been needed to achieve the same production levels since 1961 while holding yields and fertilizer intensities constant”
    Quote in the paperSubstantial claim
  • Findingown data

    In the AW2 scenario, 864 Mha more cropland would have been needed than in the real world.

    “or 864 Mha more cropland than in the RW”
    Quote in the paperSubstantial claim
  • Findingcitation

    The 161 GtC avoided in the AW1 scenario corresponds to 34% of the total 478 GtC emitted by humans between 1850 and 2005.

    “This corresponds to 34% of the total 478 GtC emitted by humans between 1850 and 2005”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [11] Canadell JG, et al. Contributions to accelerating atmospheric CO2 growth from economic activity, carbon intensity, and efficiency of natural sinks. Proc Natl Acad Sci USA. 2007;104:18866–18870. doi: 10.1073/pnas.0702737104. [[DOI](https://doi.org/10.1073/pnas.0702737104)] [[PMC free article](/articles/PMC2141868/)] [[PubMed](https://pubmed.ncbi.nlm.nih.gov/17962418/)] [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Proc%20Natl%20Acad%20Sci%20USA&title=Contributions%20to%20accelerating%20atmospheric%20CO2%20growth%20from%20economic%20activity,%20carbon%20intensity,%20and%20e source

      Not checked in the free run.

  • Findingown data

    The average carbon content (soil + biomass) of land converted in the AW scenarios (and spared in the RW) is ~105 tC/ha.

    “we find that the average carbon content (soil + biomass) of land converted in the AW scenarios (and spared in the RW) to be ~105 tC/ha”
    Quote in the paperSubstantial claim
  • May combine two claims. 20
  • Classified as probably not a substantial claim. 28

  • May combine two claims.

    Findingreasoning

    Attributing 34% of productivity growth (and thus carbon savings, or ∼36 tC/ha) to agricultural R&D and assuming that 70% of R&D is relevant to farm productivity gives a carbon price of $14.74 in AW1 and $27.43 in AW2 per metric ton of carbon.

    “Attributing 34% of productivity growth (and thus carbon savings, or ∼36 tC/ha) to agricultural R&D and assuming that 70% of R&D is relevant to farm productivity gives a carbon price of $14.74 in AW1 and $27.43 in AW2 (per metric ton of carbon; plotted triangle).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [31] Alston JM, Beddow JM, Pardey PG. Agricultural research, productivity, and food prices in the long run. Science. 2009;325:1209–1210. doi: 10.1126/science.1170451. [[DOI](https://doi.org/10.1126/science.1170451)] [[PubMed](https://pubmed.ncbi.nlm.nih.gov/19729642/)] [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Science&title=Agricultural%20research,%20productivity,%20and%20food%20prices%20in%20the%20long%20run&author=JM%20Alston&author=JM%20Beddow&author=PG%20Pardey&volume=325&publication_year=2009&pages=1209-1210&pmid=19729642&doi=10.1126/science.1170451&)] source

      Not checked in the free run.

    • cites [32] Evenson RE, Pray C, Rosegrant MW. Agricultural Research and Productivity Growth in India. Washington, DC: International Food Policy Research Institute; 1998. [[Google Scholar](https://scholar.google.com/scholar_lookup?title=Agricultural%20Research%20and%20Productivity%20Growth%20in%20India&author=RE%20Evenson&author=C%20Pray&author=MW%20Rosegrant&publication_year=1998&)]

      Not checked in the free run.

    • cites [33] Rosegrant MW, Evenson RE. Agricultural productivity and sources of growth in South Asia. Am J Agric Econ. 1992;74:757–761. [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Am%20J%20Agric%20Econ&title=Agricultural%20productivity%20and%20sources%20of%20growth%20in%20South%20Asia&author=MW%20Rosegrant&author=RE%20Evenson&volume=74&publication_year=1992&pages=757-761&)] source

      Not checked in the free run.

  • May combine two claims.

    Findingown data

    In the AW2 scenario, fertilizer use rises from 31 Mt of nutrient to 67 Mt of nutrient, representing the same constant 1961 intensity of 32 kg/ha.

    “Fertilizer use in the AW2 scenario rises from 31 Mt of nutrient to 67 Mt of nutrient, representing the same constant 1961 intensity of 32 kg/ha”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingcitation

    The size and cost of this carbon sink (over 45 years, 3.6 +2.3/−0.9 GtC/yr for AW1 and 1.9 ± 0.5 GtC/yr for AW2) compares favorably with other proposed mitigation options available at <$73/tC in buildings (1.49 GtC/yr), energy supply (0.49 GtC/yr), transportation (0.46 GtC/yr), and industry (0.30 GtC/yr).

    “The size and cost of this carbon sink (over 45 years, 3.6 +2.3/−0.9 GtC/yr for AW1 and 1.9 ± 0.5 GtC/yr for AW2) compares favorably with other proposed mitigation options available at <$73/tC in buildings (1.49 GtC/yr), energy supply (0.49 GtC/yr), transportation (0.46 GtC/yr), and industry (0.30 GtC/yr)”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [36] Barker T, et al. Mitigation from a cross-sectoral perspective. In: Metz B, Davidson O, Bosch P, Dave R, Meyer L, editors. Climate Change 2007: MitigationContribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK: Cambridge University Press; 2007. pp. 619–690. [[Google Scholar](https://scholar.google.com/scholar_lookup?title=Climate%20Change%202007:%20MitigationContribution%20of%20Working%20Group%20III%20to%20the%20Fourth%20Assessment%20Report%20of%20the%20Intergovernmental%20Panel%20on%20Climate%20Change&author=T%20Barker&p source

      Not checked in the free run.

  • May combine two claims.

    Findingreasoning

    Assuming the entirety of public and private investment in agriculture between 1961 and 2005 (estimated at $1,152 billion US) contributed to yield gains, the carbon price for avoided emissions is $7.16 in AW1 and $13.32 in AW2 per metric ton of carbon.

    “we assume that the entirety of public and private investment in agriculture between 1961 and 2005 (estimated at $1,152 billion US) contributed to yield gains achieved during that time period.”
    • Also stated in: § Cost of Carbon Savings. · plain
      “These two values yield a carbon price for avoided emissions of $7.16 in AW1 and $13.32 in AW2 (per metric ton of carbon; plotted square).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingcitation

    In the real world, total fertilizer use increased to 136 kg/ha, or 165 Mt total.

    “In the RW, total fertilizer use increased to 136 kg/ha, or 165 Mt total”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given

    In the AW1 scenario, fertilizer use increases from 31 Mt of nutrient to 88 Mt of nutrient, representing a constant mean annual intensity of 32 kg/ha.

    “Fertilizer use in the AW1 scenario increases from 31 Mt of nutrient to 88 Mt of nutrient, representing a constant mean annual intensity of 32 kg/ha.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingcitation

    The paper's estimates of emissions from agricultural soils agree with those reported previously.

    “Our estimates agree with those reported previously ([12](#r12), [49](#r49), [50](#r50)).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [12] U.S. Environmental Protection Agency . Global Anthropogenic Non-CO2 Greenhouse Gas Emissions, 1990–2020. EPA Report 430-R-06-003. Washington, DC: U.S. Environmental Protection Agency; 2006. [[Google Scholar](https://scholar.google.com/scholar_lookup?title=Global%20Anthropogenic%20Non-CO2%20Greenhouse%20Gas%20Emissions,%201990%E2%80%932020.%20EPA%20Report%20430-R-06-003.&publication_year=2006&)]

      Not checked in the free run.

    • cites [49] Davidson EA. The contribution of manure and fertilizer nitrogen to atmospheric nitrous oxide since 1860. Nat Geosci. 2009;2:659–662. [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Nat%20Geosci&title=The%20contribution%20of%20manure%20and%20fertilizer%20nitrogen%20to%20atmospheric%20nitrous%20oxide%20since%201860&author=EA%20Davidson&volume=2&publication_year=2009&pages=659-662&)] source

      Not checked in the free run.

    • cites [50] Mosier A, et al. Closing the global N2O budget: Nitrous oxide emissions through the agricultural nitrogen cycle. Nutr Cycl Agroecosyst. 1998;52:225–248. [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Nutr%20Cycl%20Agroecosyst&title=Closing%20the%20global%20N2O%20budget:%20Nitrous%20oxide%20emissions%20through%20the%20agricultural%20nitrogen%20cycle&author=A%20Mosier&volume=52&publication_year=1998&pages=225-248&)] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingnone given

    Between 1961 and 2005, global total area equipped for irrigation increased from 139 Mha to 284 Mha, with 75% of this change in Asia (19% in the Americas and Europe, 4% in Africa, and 1% in Oceania).

    “between 1961–2005, global total area equipped for irrigation increased from 139 Mha to 284 Mha, with 75% of this change in Asia (19% in the Americas and Europe, 4% in Africa, and 1% in Oceania).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The main components of agricultural emissions outside of land use change are N2O released from soils related to the application of nitrogenous fertilizer (38%), CH4 from livestock enteric fermentation, and CH4 and N2O from manure management (38%), CH4 from cultivation of rice (11%), and CH4 and N2O from burning of savannah, forest, and agricultural residues (13%).

    “The main components of agricultural emissions outside of land use change are N2O released from soils related to the application of nitrogenous fertilizer (38%), CH4 from livestock enteric fermentation, and CH4 and N2O from manure management (38%), CH4 from cultivation of rice (11%), and CH4 and N2O from burning of savannah, forest, and agricultural residues (13%)”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [12] U.S. Environmental Protection Agency . Global Anthropogenic Non-CO2 Greenhouse Gas Emissions, 1990–2020. EPA Report 430-R-06-003. Washington, DC: U.S. Environmental Protection Agency; 2006. [[Google Scholar](https://scholar.google.com/scholar_lookup?title=Global%20Anthropogenic%20Non-CO2%20Greenhouse%20Gas%20Emissions,%201990%E2%80%932020.%20EPA%20Report%20430-R-06-003.&publication_year=2006&)]

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Modified rice drainage and straw incorporation practices could reduce global CH4 emissions from rice cultivation by up to 30%.

    “it has been estimated that modified rice drainage and straw incorporation practices could reduce global CH4 emissions from rice cultivation by up to 30%”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [14] Yan X, Akiyama H, Yagi K, Akimoto H. Global estimations of the inventory and mitigation potential of methane emissions from rice cultivation conducted using the 2006 Intergovernmental Panel on Climate Change guidelines. Global Biogeochem Cycles. 2009 10.1029/2008GB003299. [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Global%20Biogeochem%20Cycles&title=Global%20estimations%20of%20the%20inventory%20and%20mitigation%20potential%20of%20methane%20emissions%20from%20rice%20cultivation%20conducted%20using%20the%202006%20Intergovernmental%20Panel%20on%20Climate%20Change%20guideli source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In 2005, agricultural production accounted for 1.4-1.7 GtC emissions (10-12% of total anthropogenic GHG emissions), including 0.76 GtC equivalent N2O and 0.90 GtC equivalent CH4.

    “In 2005, agricultural production accounted for 1.4–1.7 gigatons of carbon (GtC) emissions (10–12% of total anthropogenic GHG emissions; 1 GtC = 109 metric tons of carbon), including 0.76 GtC equivalent N2O and 0.90 GtC equivalent CH4”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [10] Smith P, et al. Agriculture. In: Metz B, Davidson O, Bosch P, Dave R, Meyer L, editors. Climate Change 2007: Mitigation Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK: Cambridge University Press; 2007. pp. 497–540. [[Google Scholar](https://scholar.google.com/scholar_lookup?title=Climate%20Change%202007:%20Mitigation%20Contribution%20of%20Working%20Group%20III%20to%20the%20Fourth%20Assessment%20Report%20of%20the%20Intergovernmental%20Panel%20on%20Climate%20Change&author=P%20Smith&publication_year=2007&)] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationreasoning

    Improvement of crop yields should be prominent among a portfolio of strategies to reduce global greenhouse gas emissions.

    “Improvement of crop yields should therefore be prominent among a portfolio of strategies to reduce global greenhouse gas emissions”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    In 2005, land use change accounted for an additional 1.5 GtC emissions.

    “In the same year, land use change (e.g., harvesting of forest products and clearing for agriculture) accounted for an additional 1.5 GtC emissions”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [11] Canadell JG, et al. Contributions to accelerating atmospheric CO2 growth from economic activity, carbon intensity, and efficiency of natural sinks. Proc Natl Acad Sci USA. 2007;104:18866–18870. doi: 10.1073/pnas.0702737104. [[DOI](https://doi.org/10.1073/pnas.0702737104)] [[PMC free article](/articles/PMC2141868/)] [[PubMed](https://pubmed.ncbi.nlm.nih.gov/17962418/)] [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Proc%20Natl%20Acad%20Sci%20USA&title=Contributions%20to%20accelerating%20atmospheric%20CO2%20growth%20from%20economic%20activity,%20carbon%20intensity,%20and%20e source

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    The potential to avoid future emissions may be larger and more cost-effective than the 161 GtC of emissions avoided thus far, given that current cropland expansion often occurs in tropical forests and that the remaining forests are carbon-rich relative to many cleared forests.

    “Even if yield gains over the next four decades are smaller than those of the previous four decades, the potential to avoid future emissions may be larger and more cost-effective than the 161 GtC of emissions avoided thus far, given that current cropland expansion often occurs in tropical forests and that the remaining forests are carbon-rich relative to many cleared forests”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [43] Loarie SR, Asner GP, Field CB. Boosted carbon emissions from Amazon deforestation. Geophys Res Lett. 2009;36:L14810. [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Geophys%20Res%20Lett&title=Boosted%20carbon%20emissions%20from%20Amazon%20deforestation&author=SR%20Loarie&author=GP%20Asner&author=CB%20Field&volume=36&publication_year=2009&pages=L14810&)] source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Study design and conductcitation

    For land conversion emissions, the study assumes that cropland expansion occurred in the same proportions by biome in the AW1 scenario as in the real world.

    “For “land conversion” emissions, we assume that cropland expansion occurred in the same proportions by biome in the AW1 scenario as in the RW, calculated as in previous studies”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [26] Ramankutty N, Foley JA. Estimating historical changes in global land cover: Croplands from 1700 to 1992. Global Biogeochem Cycles. 1999;13:997–1027. [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Global%20Biogeochem%20Cycles&title=Estimating%20historical%20changes%20in%20global%20land%20cover:%20Croplands%20from%201700%20to%201992&author=N%20Ramankutty&author=JA%20Foley&volume=13&publication_year=1999&pages=997-1027&)] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Study design and conductnone given

    The study assumes that land expansion occurred across different biomes at the same percentages as in the real world, and assumes the same uncertainty of ±20% for carbon values.

    “We assume that land expansion occurred across different biomes at the same percentages as in the RW, and we assume the same uncertainty of ±20% for carbon values.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductcitation

    The study assumes that carbon losses from land converted to cropland occur over 1 year and that carbon sequestration in abandoned cropland occurs over 20 years.

    “We follow Gibbs et al. ([27](#r27)) and the 2006 Intergovernmental Panel on Climate Change (IPCC) Tier 1 GHG emissions calculations guidelines ([47](#r47)) and assume that carbon losses from land converted to cropland occur over 1 year and that carbon sequestration in abandoned cropland occurs over 20 years.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [27] Gibbs HK, et al. Carbon payback times for crop-based biofuel expansion in the tropics: The effects of changing yield and technology. Environ Res Lett. 2008;3:034001. [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Environ%20Res%20Lett&title=Carbon%20payback%20times%20for%20crop-based%20biofuel%20expansion%20in%20the%20tropics:%20The%20effects%20of%20changing%20yield%20and%20technology&author=HK%20Gibbs&volume=3&publication_year=2008&pages=034001&)] source

      Not checked in the free run.

    • cites [47] Eggleston S, Buendia L, Miwa K, Ngara T, Tanabe K, editors. 2006 IPCC Guidelines for National Greenhouse Gas Inventories. Hayama, Japan: Institute for Global Environmental Strategies; 2006. [[Google Scholar](https://scholar.google.com/scholar_lookup?title=2006%20IPCC%20Guidelines%20for%20National%20Greenhouse%20Gas%20Inventories.&publication_year=2006&)]

      Not checked in the free run.

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductcitation

    The study assumes 70% of land converted to cropland is for crops and 30% for tree plantations, that land converted for crops results in loss of 25% of soil carbon, and that land converted to plantations results in loss of 10% of soil carbon.

    “We assume 70% of land converted to cropland is for crops, and 30% for tree plantations based on FAO trends ([1](#r1)), and that land converted for crops results in loss of 25% of soil carbon, and land converted to plantations results in loss of 10% of soil carbon.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [1] Food and Agriculture Organization of the United Nations. Food and Agriculture Organization of the United Nations statistical database. Available at: <http://faostat.fao.org/>. Accessed June 30, 2009.

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Study design and conductreasoning

    The AW2 scenario projects 1961 per capita supply forward, maintaining 1961 living standards without the increase in supply that drove prices down in the real world.

    “This scenario thus provides a reasonable lower bound on carbon savings by projecting the 1961 per capita supply forward (i.e., maintaining 1961 living standards without the increase in supply that drove prices down in the RW).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Study design and conductnone given

    The study assumes that after conversion to agricultural land, soil organic carbon content remains the same in the real world and AW scenarios.

    “We assume that after a conversion to agricultural land, soil organic carbon content remains the same in the RW and AW scenarios.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Total real-world annual livestock-related GHG emissions in 2004 have been estimated as ∼1.94 GtC/yr equivalent, of which ∼0.68 GtC/yr equivalent is from land use changes.

    “Total RW annual livestock-related GHG emissions in 2004 (including feed production, farm operations, enteric fermentation, manure management, and soil emissions from pasture land and feed crops) have been estimated as ∼1.94 GtC/yr equivalent (∼7.1 GtCO2e/yr), of which ∼0.68 GtC/yr equivalent (∼2.5 GtCO2e/yr) is from land use changes”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [44] Steinfeld H, Gerber P, Wassenaar TD, Castel V, de Haan C. Livestock's Long Shadow: Environmental Issues and Options. Rome: Food and Agriculture Organization of the United Nations; 2006. [[Google Scholar](https://scholar.google.com/scholar_lookup?title=Livestock's%20Long%20Shadow:%20Environmental%20Issues%20and%20Options&author=H%20Steinfeld&author=P%20Gerber&author=TD%20Wassenaar&author=V%20Castel&author=C%20de%20Haan&publication_year=2006&)]

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The study does not include any pesticides, fuel use, or transport in the AW2 calculations.

    “As in the AW1 scenario, we do not include any pesticides, fuel use, or transport in the AW2 calculations.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Study design and conductreasoning

    The study assumes that burning of agricultural residues is the same in the real world and AW1.

    “Similarly, we assume that burning of agricultural residues is the same in both cases (because total production is the same).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The study does not assume any gains in soil organic carbon content in the AW scenarios between 1961 and 2005.

    “Although management practices, such as conservation tillage, can increase soil organic carbon content in both extensive and intensive systems ([15](#r15), [16](#r16)), we do not assume any such gains in the AW scenarios between 1961 and 2005.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [15] Lal R. Soil carbon sequestration impacts on global climate change and food security. Science. 2004;304:1623–1627. doi: 10.1126/science.1097396. [[DOI](https://doi.org/10.1126/science.1097396)] [[PubMed](https://pubmed.ncbi.nlm.nih.gov/15192216/)] [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Science&title=Soil%20carbon%20sequestration%20impacts%20on%20global%20climate%20change%20and%20food%20security&author=R%20Lal&volume=304&publication_year=2004&pages=1623-1627&pmid=15192216&doi=10.1126/science.1097396&)] source

      Not checked in the free run.

    • cites [16] West TO, Post WM. Soil organic carbon sequestration rates by tillage and crop rotation: A global data analysis. Soil Sci Soc Am J. 2002;66:1930–1946. [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Soil%20Sci%20Soc%20Am%20J&title=Soil%20organic%20carbon%20sequestration%20rates%20by%20tillage%20and%20crop%20rotation:%20A%20global%20data%20analysis&author=TO%20West&author=WM%20Post&volume=66&publication_year=2002&pages=1930-1946&)] source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Study design and conductcitation

    Methane emissions from rice cultivation and GHGs from the burning of rice straw were calculated following the methodology outlined by Yan et al.

    “We follow the methodology outlined by Yan ([14](#r14), [51](#r51)) to calculate methane emissions from rice cultivation and GHGs from the burning of rice straw.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [14] Yan X, Akiyama H, Yagi K, Akimoto H. Global estimations of the inventory and mitigation potential of methane emissions from rice cultivation conducted using the 2006 Intergovernmental Panel on Climate Change guidelines. Global Biogeochem Cycles. 2009 10.1029/2008GB003299. [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Global%20Biogeochem%20Cycles&title=Global%20estimations%20of%20the%20inventory%20and%20mitigation%20potential%20of%20methane%20emissions%20from%20rice%20cultivation%20conducted%20using%20the%202006%20Intergovernmental%20Panel%20on%20Climate%20Change%20guideli source

      Not checked in the free run.

    • cites [51] Yan X, Yagi K, Akiyama H, Akimoto H. Statistical analysis of the major variables controlling methane emission from rice fields. Glob Change Biol. 2005;11:1131–1141. [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Glob%20Change%20Biol&title=Statistical%20analysis%20of%20the%20major%20variables%20controlling%20methane%20emission%20from%20rice%20fields&author=X%20Yan&author=K%20Yagi&author=H%20Akiyama&author=H%20Akimoto&volume=11&publication_year=2005&pages=1131-1141&)] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    The study does not explicitly calculate emissions for livestock, burning of agricultural residues, pesticide and fuel use, agricultural machinery, or irrigation in the real world and AW scenarios.

    “We do not explicitly calculate emissions for livestock, burning of agricultural residues, pesticide and fuel use, agricultural machinery, or irrigation in the RW and AW scenarios, but discuss assumptions and potential differences in these sectors below.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductnone given

    The AW1 scenario assumes the same crop yields and fertilizer application rates as in 1961, and scales land use and fertilizer production accordingly.

    “Specifically, we assume the same crop yields and fertilizer application rates as in 1961, and scale land use and fertilizer production accordingly”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationcitation

    Using a cost value of $2,000 per ha for irrigation investments gives a total cost of $310 billion, or just under 27% of the maximum global total agricultural investment.

    “using a value of $2,000 per ha gives a total cost of $310 billion, or just under 27% of the maximum global total agricultural investment.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [54] Inocencio A, et al. Costs and Performance of Irrigation Projects: A Comparison of Sub-Saharan Africa and Other Developing Regions. Sri Lanka: International Water Management Institute, Battaramulla; 2007. [[Google Scholar](https://scholar.google.com/scholar_lookup?title=Costs%20and%20Performance%20of%20Irrigation%20Projects:%20A%20Comparison%20of%20Sub-Saharan%20Africa%20and%20Other%20Developing%20Regions.&author=A%20Inocencio&publication_year=2007&)]

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based).

    Study design and conductnone given

    The cost-benefit analysis used baseline AW land carbon content assumptions corresponding to a global average of 105 ± 21 tC/ha lost (total, including both biomass and soil carbon losses) in conversion of other types of land to cropland.

    “We use the baseline AW land carbon content assumptions described above, which correspond to a global average of 105 ± 21 tC/ha lost (total, including both biomass and soil carbon losses) in conversion of other types of land to cropland.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductreasoning

    The study conservatively assumes that machinery use and irrigation area remained the same in AW1 and the real world.

    “Thus, we conservatively assume that machinery use and irrigation area remained the same in AW1 and RW.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    The cost-benefit analysis can be used to give an upper bound on the value of carbon savings due to agricultural investment.

    “Although carbon savings are not the only benefit of agricultural intensification, this analysis can be used to give an upper bound on the value of carbon savings due to agricultural investment.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given

    The study does not include any pesticides or fuel use in its analysis, nor does it account for any transport of food in the AW1 scenario.

    “Finally, we do not include any pesticides or fuel use in our analysis, nor do we account for any transport of food in the AW1 scenario.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductcitation

    Global total public and private agricultural investment values for 1961-2005 were estimated from Pardey et al. (2006).

    “We estimate global total public and private agricultural investment values for 1961–2005 from ([30](#r30)).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [30] Pardey PG, Beintema N, Dehmer S, Wood S. Agricultural Research: A Growing Global Divide? Washington, DC: Agricultural Science and Technology Indicators Initiative, International Food Policy Research Institute; 2006. [[Google Scholar](https://scholar.google.com/scholar_lookup?title=Agricultural%20Research:%20A%20Growing%20Global%20Divide?&author=PG%20Pardey&author=N%20Beintema&author=S%20Dehmer&author=S%20Wood&publication_year=2006&)]

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Study design and conductcitation

    Emissions from agricultural soils were calculated following IPCC Tier 1 GHG inventory guidelines by crop group.

    “To calculate emissions from agricultural soils, we follow IPCC Tier 1 GHG inventory guidelines by crop group ([47](#r47)).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [47] Eggleston S, Buendia L, Miwa K, Ngara T, Tanabe K, editors. 2006 IPCC Guidelines for National Greenhouse Gas Inventories. Hayama, Japan: Institute for Global Environmental Strategies; 2006. [[Google Scholar](https://scholar.google.com/scholar_lookup?title=2006%20IPCC%20Guidelines%20for%20National%20Greenhouse%20Gas%20Inventories.&publication_year=2006&)]

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based).

    Study design and conductreasoning

    The study assumes that livestock populations are the same in the real world and AW1, because total food and feed production do not change.

    “We assume that livestock populations are the same in the RW and AW1, because total food and feed production do not change, and thus emissions due to enteric fermentation, manure management, and land conversion to grazing land are identical in both scenarios.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductcitation

    The study assigns biomass and soil organic carbon content values to each biome from the literature and assumes an uncertainty of ±20% in these values.

    “We assign biomass and soil organic carbon content values to each biome from the literature ([27](#r27)–[29](#r29)), and assume an uncertainty of ±20% in these values, reflective of regional differences”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [27] Gibbs HK, et al. Carbon payback times for crop-based biofuel expansion in the tropics: The effects of changing yield and technology. Environ Res Lett. 2008;3:034001. [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Environ%20Res%20Lett&title=Carbon%20payback%20times%20for%20crop-based%20biofuel%20expansion%20in%20the%20tropics:%20The%20effects%20of%20changing%20yield%20and%20technology&author=HK%20Gibbs&volume=3&publication_year=2008&pages=034001&)] source

      Not checked in the free run.

    • cites [28] Gibbs HK, Brown S, Niles JO, Foley JA. Monitoring and estimating tropical forest carbon stocks: Making REDD a reality. Environ Res Lett. 2007;2:045023. [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Environ%20Res%20Lett&title=Monitoring%20and%20estimating%20tropical%20forest%20carbon%20stocks:%20Making%20REDD%20a%20reality&author=HK%20Gibbs&author=S%20Brown&author=JO%20Niles&author=JA%20Foley&volume=2&publication_year=2007&pages=045023&)] source

      Not checked in the free run.

    • cites [29] Houghton RA. The annual net flux of carbon to the atmosphere from changes in land use, 1850–1990. Tellus B. 1999;51:298–313. [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Tellus%20B&title=The%20annual%20net%20flux%20of%20carbon%20to%20the%20atmosphere%20from%20changes%20in%20land%20use,%201850%E2%80%931990&author=RA%20Houghton&volume=51&publication_year=1999&pages=298-313&)] source

      Not checked in the free run.

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    The global population is expected to reach 8.9 billion by 2050, with food demand expected to rise by 70%.

    “The global population is expected to reach 8.9 billion by 2050, with food demand expected to rise by 70%”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [42] Food and Agriculture Organization of the United Nations . World Agriculture: Towards 2030/2050. Rome: Food and Agriculture Organization of the United Nations; 2006. [[Google Scholar](https://scholar.google.com/scholar_lookup?title=World%20Agriculture:%20Towards%202030/2050&publication_year=2006&)]

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Without the Green Revolution's increased agricultural yields, international shipments of food from developed to developing countries would have increased on the order of 30%, and crop area would still have increased by 2.8-4.9% more than it did historically.

    “international shipments of food from developed to developing countries would have increased on the order of 30%, and crop area would still have increased by 2.8–4.9% more than it did historically”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [22] Evenson RE, Gollin D. Assessing the impact of the green revolution, 1960 to 2000. Science. 2003;300:758–762. doi: 10.1126/science.1078710. [[DOI](https://doi.org/10.1126/science.1078710)] [[PubMed](https://pubmed.ncbi.nlm.nih.gov/12730592/)] [[Google Scholar](https://scholar.google.com/scholar_lookup?journal=Science&title=Assessing%20the%20impact%20of%20the%20green%20revolution,%201960%20to%202000&author=RE%20Evenson&author=D%20Gollin&volume=300&publication_year=2003&pages=758-762&pmid=12730592&doi=10.1126/science.1078710&)] source

      Not checked in the free run.

    • cites [23] Evenson RE, Gollin D, editors. Crop Variety Improvement and Its Effect on Productivity: The Impact of International Agricultural Research. Wallingford, UK: CABI; 2003. [[Google Scholar](https://scholar.google.com/scholar_lookup?title=Crop%20Variety%20Improvement%20and%20Its%20Effect%20on%20Productivity:%20The%20Impact%20of%20International%20Agricultural%20Research&publication_year=2003&)] source

      Not checked in the free run.

38 of 38

  • The authors state this as an assumption.

    The AW1 scenario exogenously specifies that demand for agricultural products over time would have been identical without yield improvements.

    “for example, the AW1 scenario exogenously specifies that demand for agricultural products over time would have been identical without yield improvements, thus ignoring the role of food prices (which fell in real terms by ∼40% between 1965 and 2000)”

  • The authors state this as an assumption.

    Even without increased agricultural productivity, income growth from productivity gains in other sectors, as well as higher crop demand for nonfood uses, would nevertheless have kept per capita demand at 1961 levels despite any price increases.

    “However, we assume that even without increased agricultural productivity, income growth from productivity gains in other sectors, as well as higher crop demand for nonfood uses, would nevertheless have kept per capita demand at 1961 levels despite any price increases”

  • The authors state this as an assumption.

    Yield advancements are directly related to research funding.

    “Assuming that yield advancements are directly related to research funding, we assess the cost-effectiveness of mitigation through yield improvements using the ratio of public and private spending on agricultural research since 1961”

  • The authors state this as an assumption.

    A slightly more conservative assumption that 70% of all public and private research was relevant to yield improvements.

    “For the global case, a slightly more conservative assumption that 70% of all public and private research was relevant to yield improvements gives a cumulative 45-year total of $806 billion in agricultural investments.”

  • The authors state this as an assumption.

    A conservative estimate that the AW2 scenario included no intensive livestock operations.

    “thus, a conservative estimate that the AW2 scenario included no intensive livestock operations results in a savings of up to ∼0.58 GtC/yr (∼2.1 GtCO2e/yr) in the livestock sector compared with the RW.”

  • The authors state this as an assumption.

    Emissions due to burning of agricultural residues can be conservatively assumed to be 15% lower in AW2 than the real world.

    “Emissions due to burning of agricultural residues can be conservatively assumed to be 15% lower in AW2 than RW (the difference in total production), although we do not calculate burning emissions for the RW.”

  • The authors state this as an assumption.

    An assumption of constant intensity for machinery and irrigation results in 5% more irrigated land and 17% fewer agricultural tractors in the AW2 scenario compared with the real world.

    “An assumption of constant intensity for machinery and irrigation results in 5% more irrigated land and 17% fewer agricultural tractors in the AW2 scenario compared with the RW.”

  • The authors state this as an assumption.

    Fertilizer application rates remain at 1961 levels in both AW scenarios.

    “We assume fertilizer application rates remain at 1961 levels in both AW scenarios, and scale fertilizer consumption and associated production emissions accordingly.”

  • The authors state this as an assumption.

    For both AW expansion scenarios, the percentages of rain-fed and irrigated rice systems are the same as in the RW, and drainage practices and organic amendments are the same in each scenario.

    “For both AW expansion scenarios, we assume that the percentages of rain-fed and irrigated systems are the same as in the RW, and that drainage practices and organic amendments are the same in each scenario.”

  • The authors state this as an assumption.

    The same public funding percentage applies to developing and developed world when estimating total agricultural spending in each time period.

    “We use the values for public research spending in 1981, 1991, and 2000, and use the same public funding percentage for developing and developed world to estimate total spending in each time period.”

  • The authors state this as an assumption.

    Agricultural investment spending grew at a rate of 4.5% between 1961 and 1981.

    “We assume a growth rate of 4.5% in spending between 1961–1981, and use the 1981 value to extrapolate back in time”

  • The authors state this as an assumption.

    Agricultural investment increased linearly from 1981 to 2000.

    “we assume a linear increase from 1981 to 2000”

  • The authors state this as an assumption.

    Agricultural investment grew at 2.1% annually from 2001 to 2005.

    “we estimate the values for 2001–2005 assuming a 2.1% annual growth in agricultural investment ([30](#r30)).”
13 of 13

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Human use of land causes major global changes in biodiversity, biogeochemistry, geomorphic processes, and climate.

    “Human populations and their use of land have now transformed ecosystem pattern and process across most of the terrestrial biosphere (1, 2), causing major global changes in biodiversity (3), biogeochemistry (4–6), geomorphic processes (7), and climate (8).”

    From Used planet: a global history (2013) · cites this paper as [6]

  • Practices that increase C inputs include improved varieties or species with greater root mass, crop rotations that provide greater C inputs, more residue retention, and cover crops during fallow periods.

    “Practices that increase C inputs include (i) improved varieties or species with greater root mass to deposit C in deeper layers where turnover is slower 21 , (ii) adopting crop rotations that provide greater C inputs 22 , (iii) more residue retention 23 , and (iv) cover crops during fallow periods to provide year-round C inputs (Fig. 1).22,24”

    From Climate-smart soils (2016) · cites this paper as [23]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

  • Irrigation investment total does not match area increase

    Minor

    The stated increase from 139 to 284 Mha is 145 million hectares. At $2,000 per hectare, that costs $290 billion, not $310 billion.

    Reported 310000 · recomputed 290000

1 of 1

Cites

Flagged first, then by citations

1 of the 53 references couldn’t be matched to a known paper.

Research works printed but not linked: 3

  1. ; U.S. Environmental Protection Agency Global Anthropogenic Non-CO2 Greenhouse Gas Emissions, 1990–2020. EPA Report 430-R-06-003. (U.S. Environmental Protection Agency, Washington, DC, 2006).
  2. 10.1079/sum2005291 · DOI
  3. RE Evenson, C Pray, MW Rosegrant Agricultural Research and Productivity Growth in India (International Food Policy Research Institute, Washington, DC, 1998).

Cited by

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Related

Authors
Burney, J. A., Davis, S. J., & Lobell, D. B.
Affiliations
  • Stanford University (US)
  • Carnegie Institution for Science (US)
ORCID
Venue
Proceedings of the National Academy of Sciences
Publisher
National Academy of Sciences
Published
2010-06-15
Volume
107
Issue
26
Pages
12052-12057
ISSN
  • 0027-8424 (ISSN-L)
  • 1091-6490
DOI
10.1073/pnas.0914216107
PMC
PMC2900707
OpenAlex
W2149362589
Semantic Scholar
977c80cae562c86e67f1733bd4a17afe8e827061
Cited by
1,128
References
53
Citations by year
2026: 59 · 2025: 53 · 2024: 62 · 2023: 69 · 2022: 76 · 2021: 99 · 2020: 74 · 2019: 87 · 2018: 72 · 2017: 56 · 2016: 57 · 2015: 66 · 2014: 73 · 2013: 76 · 2012: 80
FWCI
65.01
Type
journal article
Language
en
Open access
Locations
  • Proceedings of the National Academy of Sciences (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
  • eScholarship (California Digital Library) (submittedVersion, cc-by)
Funders
  • National Aeronautics and Space Administration (NNX08AV25G)
  • Carnegie Institution of Washington
Topics
  • Physical Sciences › Environmental Science › Ecology › Agriculture Sustainability and Environmental Impact
  • Life Sciences › Agricultural and Biological Sciences › Ecology, Evolution, Behavior and Systematics › Climate change impacts on agriculture
  • Social Sciences › Economics, Econometrics and Finance › Economics and Econometrics › Climate Change Policy and Economics
Keywords
greenhouse gas emissions reduction, agricultural intensification, agricultural emissions, crop yield improvement, fertilizer emissions, CO2 emissions, agricultural research investment, land use change, energy crops

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-08.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-08.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

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