6th AgMIP Global Workshop Abstracts – Session 1.4


Session 1.1 Seasonal Forecasts and Climate Extremes

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Session 1.4: Oral Presentation

Title: Regional disparities in the beneficial
effects of rising CO2 concentrations on crop water productivity

Authors: Delphine Deryng1, J. Elliott2,
C. Folberth2, C. Müller3, T. A. M. Pugh4, K.
J. Boote5, D. Conway6, A. C. Ruane7, Dieter
Gerten3, J. W. Jones5, N. Khabarov2, S. Olin8,
S. Schaphoff3, E. Schmid9, H. Yang10, and C.
1 University of Chicago & NASA GISS, USA, 2 IIASA,
Austria, 3 PIK, Germany, 4 University of Birmingham, UK, 5
University of Florida, USA, 6 LSE, UK, 7 NASA Goddard
Institute for Space Studies, USA, 8 Lund University, Sweden, 9
Boku, Austria, 10 EAWAG, Switzerland

Abstract: Rising atmospheric CO2
concentrations ([CO2]) are expected to enhance photosynthesis and
reduce crop water use. However, there is high uncertainty about the global
implications of these effects for future crop production and agricultural water
requirements under climate change. Here we combine results from networks of
field experiments and global crop models to present a spatially explicit global
perspective on crop water productivity (CWP, the ratio of crop yield to
evapotranspiration) for wheat, maize, rice and soybean under elevated [CO2]
and associated climate change projected for a high-end greenhouse gas emissions
scenario. We find CO2 effects increase global CWP by
10[0;47]%–27[7;37]% (median[interquartile range] across the model ensemble) by
the 2080s depending on crop types, with particularly large increases in arid
regions (by up to 48[25;56]% for rainfed wheat). If realized in the fields, the
effects of elevated [CO2] could considerably mitigate global yield
losses whilst reducing agricultural consumptive water use (4–17%). We identify
regional disparities driven by differences in growing conditions across
agro-ecosystems that could have implications for increasing food production
without compromising water security. Finally, our results demonstrate the need
to expand field experiments and encourage greater consistency in modelling the
effects of rising [CO2] across crop and hydrological modelling

Session 1.4: Oral Presentation

Title: Impacts of soil data uncertainty on crop
yield estimates in a global gridded crop model

Authors: Christian Folberth1, R. Skalsky2,
E. Moltchanova2, J. Balkovic2, L. B. Azevedo2,
M. Obersteiner2, and M. van der Velde3

Abstract: Global
gridded crop models (GGCMs) are frequently used for assessments of climate
change impacts on crop yields and externalities of agricultural production.
Whereas the influence of climate data and projections from general circulation
models on GGCM simulations has frequently been investigated in the past, the
influence of soil data has so far been neglected at the global scale. However,
recently compiled global soil datasets such as the Harmonized World Soil
Database usually provide various soil types for each grid cell globally, of
which usually only the most dominant one is taken into account in GGCM
simulations. As cropland is often scattered and very specific soils may be
cultivated in a certain region, the most dominant soil may however not be representative
for a specific grid. Comparing yield variability caused by selecting all
possible soils in each grid for a GGCM simulation to weather-induced yield
variability shows that without fertilizer application, yield variability
related to soil types generally outweighs the simulated inter-annual
variability due to weather. At increasing fertilizer application rates and with
sufficient irrigation this variability is reduced until it is negligible.
Estimated climate change impacts on maize yields for a business as usual crop
management scenario resulted in either negative or positive yield changes
depending on the chosen soil type. This highlights soils’ capacity to either
buffer or amplify climate and weather effects. The findings call for
improvements in soil data for crop modelling, the spatial allocation of
cropland and soil types and more explicit accounting for soil variability in
GGCM simulations.

Session 1.4: Oral Presentation

Title: An integrated assessment of climate
change impacts and adaptation in smallholder crop-livestock systems in Kenya

Authors: Lieven Claessens1, S. Gummadi2,
M. Kilavi3, A. Oyoo1, J. Recha4, C. Mwongera5,
K. Shikuku5, C. Dickson6, R. Valdivia6, J.
1 ICRISAT, Kenya, 2 ICRISAT, Ethiopia, 3 Kenya
Meteorological Department, Kenya, 4 CCAFS/ILRI, Kenya, 5
CIAT, Kenya, 6 Oregon State University, USA

Abstract: Agriculture in Sub-Saharan Africa is expected to experience considerable negative impacts of climate change. Smallholder mixed crop-livestock systems are particularly vulnerable and need to adapt to sustain or improve productivity, food and nutritional security and livelihoods. Addressing adaptation in this context raises special challenges that call for an integrated, system-based approach to inform decision and policy making. This paper applies the latest methodologies and protocols of the AgMIP Regional Integrated Assessment framework to three agro-ecologies with maize-based crop-livestock systems across Kenya. The approach uses the Tradeoff Analysis model for Multi-Dimensional impact assessment (TOA-MD), which ex ante simulates impacts of climate change and adaptation with associated economic, environmental and social outcomes. Characteristics of current and future agricultural systems, including land use, output and cost of production, are analyzed and compared for both current and projected future climate. The current agricultural systems are characterized based on a household survey of 1162 households. Crop models are used to simulate impacts of climate change and adaptation on productivity. Other components of the (potentially) adapted system are parameterized based on experimental data and/or elaborated from stakeholder consultations. We also make use of socio-economic scenarios (Representative Agricultural Pathways) to answer four core questions: (i) What is the sensitivity of current agricultural production systems to climate change? (ii) What are the benefits of adaptation in current agricultural systems? (iii) What is the impact of climate change on future agricultural systems? (iv) What are the benefits of climate change adaptations? This paper presents the first results from Kenya and discusses the challenges researchers face with performing integrated assessments in the context of complex smallholder crop-livestock systems in SSA.

Session 1.4: Oral Presentation

Title: Towards a 21st Century Climate Service for small-holder farmers in Zimbabwe: Definition of the climate problem.

Authors: Elisha N Moyo1,2, F. T. Mugabe1, M. R. Ndebele-Murisa1, and A. Makarau3
1 Chinhoyi University of Technology, Chinhoyi, Zimbabwe 2
Climate Change Management Department – Ministry of Environment, Water, and Climate, Harare, Zimbabwe, 3 Meteorological Services Department, Harare, Zimbabwe

Abstract: In order to build the resilience of smallholder farmers and design a 21st century Climate Service for such communities, it is critical to first establish the climate problem in the target area. The study investigates some of the weather and climate challenges in Midlands and Masvingo Provinces of Zimbabwe and possible implications on the suitability of rain-fed maize production and livelihoods. Using both quantitative and qualitative data collection methods, the authors investigates the observed climate dynamics in the three districts and compares them with the farmers’ perceptions. Farmers’ understanding of- and ability to use weather and climate products and services in agricultural production and other forms of livelihoods were also assessed.
      Results show that farmers have observed changes in weather patterns and climate. The climate analyses ascertained comparability of observed historical trends in climate farmers’ perceptions across the three districts. They however have limited knowledge of the causes of the causes of the changes, the communities are fully aware of their levels of vulnerability and the impact of these weather and climate changes. They are also aware of their current and future adaptation needs which include: accurate and tailored (area-specific) weather and climate information; relevant extension services (in line with changing weather and climate patterns); options for diversifying livelihoods as well as innovations and appropriate technologies to respond to the weather and climate-related problems Their knowledge of the corresponding impacts in the near-future, required services and products for effective climate resilience in the 21st century could still be improved.

Session 1.4: Oral Presentation

Title: Economic Analysis of Climate Impact and
Adaptation for the Dryland Wheat System in the US Pacific Northwest

Authors: Hongliang Zhang1, J. Antle1,
J. Mu1, C. Stockle2, and J. Abatzgolou3
1 Department of Applied Economics, Oregon State University, USA, 2
Department of Biological Systems Engineering, Washington State University, USA,
3 Department of Geography, University of Idaho, USA

Abstract: The US Pacific Northwest possesses some
of the most productive dryland grain-producing soils in the world, producing
13% of the nation’s wheat supply and 80% of its specialty soft white wheat. The
long-term sustainability of agriculture in this region could be threatened by
changes in future climate and socio-economic conditions and thus critically
depends on available adaptions to these changes. This study applied the AgMIP
Regional Integrated Assessment method to assess the economic impacts of climate
change on the dryland wheat production system in the US Pacific Northwest and
likely changes in existing cropping systems in response to climate and
plausible changes in socio-economic conditions, using downscaled climate data,
site-specific crop simulations, and detailed economic data. Results show that climate
change by 2050 will increase average crop productivity and economic net returns
for the wheat production system on average in this region under most Global
Climate Models, with or without changes in socio-economic conditions. But the
economic impacts are not uniformly distributed among farms, and due to this
heterogeneity, some gain and some lose. In response to changes in climate and
socio-economic conditions, producers in this region will shift current cropping
systems towards the annual cropping system to take advantage of positive
aspects of projected climate changes or minimize adverse effects. Results also
show that the value of climate impacts and adaptations is uncertain due to
substantial uncertainties in climate model projections and the economic and
policy environment in which producers operate.

Session 1.4: Oral Presentation

Title: Management outweighs climate change on
affecting length of rice growing period for early rice and single rice in China
during 1991-2012

Authors: Xuhui Wang1, P. Ciais1,
S. Piao2, and L. Li3
1 Laboratoire des Sciences du Climat et de l’Environnement, 2
Peking University, 3 Laboratoire de Météorologie Dynamique,
Université Pierre et Marie Curie

Abstract: Whether crop phenology changes are caused by change in managements or by climate change belongs to the category of
problems known as detection-attribution. Three type of rice (early, late and single rice) in China show an average increase in Length of Growing Period (LGP) during 1991-2012: 1.0±4.8 day/decade (±standard deviation across sites) for early rice, 0.2±4.5 day/decade for late rice and 2.0±6.0 day/decade for single rice, based on observations from 141 long-term monitoring stations. Positive LGP trends are widespread, but only significant (P<0.05) at 25% of early rice, 22% of late rice and 38% of single rice sites. We developed a
Bayes-based optimization algorithm, and optimized five parameters controlling phenological development in a process-based crop model (ORCHIDEE-crop) for discriminating effects of managements from those of climate change on rice LGP in China. The results from the optimized ORCHIDEE-crop model suggest that climate change has an effect on LGP trends that depends on rice types. Climate
trends have shortened LGP of early rice (-2.0±5.0 day/decade), lengthened LGP of late rice (1.1±5.4 day/decade) and have little impacts on LGP of single rice (-0.4±5.4 day/decade). ORCHIDEE-crop simulations further show that change in transplanting date caused widespread LGP change only for early rice sites,
which offsets 65% of climate change induced shortening of LGP. The primary
drivers of LGP change are thus different among the three types of rice.
Management, including shifting transplanting dates, changes in cultivars and
agronomic practices, are predominant driver of LGP change for early and single
rice. This study shows that complex regional variations of LGP can be
reproduced with an optimized crop model. We further suggest that future rice
crop modeling in global and regional scales should consider different types of
rice and variable transplanting dates in order to better account the impacts of
management and climate change.