Archive for the ‘Simulation modeling’ Category

Using GAMS, R and LaTeX

I just came across an interesting post by Renger van Nieuwkoop on The Lazy Economist, where he writes about how to use R to produce tables from GAMS model output for use in LaTeX.

Very nice and very useful, indeed!


Strategic Foresight Conference at IFPRI

A one-day Strategic Foresight Conference took place at IFPRI Headquarters in Washington DC on November 7, 2014. Participants from leading global modeling groups, collaborating CGIAR centers and research programs, and other partners reviewed new long-term projections for global agriculture from IFPRI and other leading institutions, examined the potential impacts of climate change and other key challenges, and discussed the role of foresight work in identifying and supporting promising solutions. 

Topics included:

  • Long-term outlook and challenges for food & agriculture
  • Addressing the challenges
  • Foresight in the CGIAR

Speakers included representatives from IFPRI, GTAP & Purdue University, OECD, IIASA, CCAFS, CIMMYT and ICRISAT. Conference agenda, a webcast, as well as the presentations are available on the Global Futures & Strategic Foresight website.

RCPs, SSPs, SPAs, …. what????

At the latest with the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) a number of new acronyms started spilling out of the climate change research community to policy makers and the broader interested public. Centrally among them are RCPs, SSPs and SPAs, meaning Representative Concentration Pathways, Shared Socio-economic Pathways and Shared climate Policy Assumptions, respectively.

But what is this all about? And where do I have to look if I need more detailed information?

A nice and user-friendly introduction to the scenario framework is given at the IIASA website.

A first more detailed reference certainly is the article on A new scenario framework for Climate Change Research which forms part of a special issue A Framework for the Development of New Socio-economic Scenarios for Climate Change Research of the journal Climatic Change. The paper describes the basic concept how scenarios  that take into account the two dimensions of future climate change and socio-economic development can be formulated by combining alternative levels of radiative forcing of the climate system, described by RCPs, with alternative trajectories of future global development, described by the SSPs.

It also lines out that givens levels of radiative forcing may be attained through different climate policy designs and that different pathways of socio-economic development may require different sets of policies. This is the point where the SPAs come in, which complete the three-dimensional scenario framework.

For descriptions of the Shared Socio-economic Pathways (SSPs), another paper in the same special issue is worth reading. Details on the narratives that underlie each of the SSPs can be found in a workshop report on The Nature and Use of New Socioeconomic Pathways for Climate Change Research. The core data sets with pathways of economic growth and population growth for each SSP are accessible through the SSP Database.

The Representative Concentration Pathways (RCPs)  are dealt with extensively in another special issue on The Representative Concentration Pathways in Climatic Change. The articles in this collection give an overview on the RCPs and details on each of the RCPs that are used for the scenario framework.

The concept of Shared Policy Assumptions (SPAs)  is introduced  in a paper, which provides details on the concept and how it links into the general scenario framework.

As a nice feature, most of the information is open access.

Simulation modeling for foresight analysis and ex-ante impact assessment in potato and sweetpotato

Is it possible to use large scale agricultural simulation models for the analysis of crops like potatoes and sweetpotatoes?

Yes! The Global Futures for Agriculture and Strategic Foresight (GFSF) project, which has the objective of developing and applying an integrated simulation modeling framework for the comprehensive analysis of trends and technology impacts in the CGIAR mandate crops and systems, is doing exactly this. At least the part of this research collaboration of all in all 12 centers of the CGIAR which is taking place at the International Potato Center (CIP), as was explained in a seminar held on 24 April 2014 at the CIP Headquarters in Lima.

The core component of the modeling framework developed in the project is the International Model for Policy Analysis of Agricultural Commodities and Trade (IMPACT), an economic partial equilibrium model of the world agricultural sector. IMPACT has the capability of generating forward looking global analyses of supply, demand, prices and trade of 56 agricultural commodities in 320 geographic regions, taking into account major drivers like

Read more…

Interfacing GAMS and R

GAMS is perhaps THE programming language for developing and running optimization models. R is an excellent and efficient tool for analysing data, including producing attractive graphs.

A tool for combining the two is provided with GDXRRW. GDXRRW acts as an interface between GAMS and R and offers facilities for the transfer of data between GDX and R and a function to call GAMS from within R.

A presentation by Dirkse et al. gives an introduction to the use of GDXRRW.




Modeling climate change and agriculture: a special issue of Agricultural Economics

AgEconAgMIPA highly interesting series of articles on economic foresight modeling in the area of agriculture and climate change has been published in the January 2014 special issue “Modeling climate change and agriculture” of Agricultural Economics.

The articles present analyses of the future consequences of climate change and global socio-economic development trends for agricultural production, food consumption, along with the potential impacts of alternative policy responses to these developments. All articles are outputs of the Agricultural Model Intercomparison and Improvement Project (AgMIP) and the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP), which brought together key global economic modeling groups in a cross-model scenario comparison exercise.

The articles are not only insightful with respect to the projections themselves, but also give a very good impression of the present global economic modeling landscape. It is also highly valuable that identical scenarios have been simulated with a large number of simulation models. This provides important evidence about the degree of uncertainty in the model projections and helps understanding root causes for differences in model results.

The articles are

And what’s also great: All articles are Open Access!

Virtual potato crop modeling: A comparison of genetic coefficients of the DSSAT-SUBSTOR potato model with breeding goals for developing countries

ReportVirtual crop modeling is the representation of future genetic improvements from plant breeding in crop growth simulation models through changes in genetic coefficients or other crop model parameters with the objective of analyzing ex-ante the impacts of improved traits on crop yields and assisting breeders in their breeding efforts.

As a first step towards virtual crop modeling for the potato crop, a new working paper provides a comparison of priority breeding targets for developing country regions with genetic coefficients and other parameters of the SUBSTOR-potato model, thereby showing the potential uses of the model for that purpose.

It is shown that SUBSTOR provides scope for virtual crop modeling. Out of nine priority target traits, five can currently be dealt with in model. Adaptation to long day conditions and heat tolerance can directly be represented by adjusting the genetic coefficients of the model. High yields and drought tolerance would require changes in parameters that are currently included in the model code. Earliness would require the implementation of a new parameter in the code. Additional traits related to crop quality and resistance to biotic stress factors will require more profound changes in either the model structure or the coupling of the crop growth model with disease models.

The full working paper Virtual potato crop modeling: A comparison of genetic coefficients of the DSSAT-SUBSTOR potato model with breeding goals for developing countries is available on ZENODO. The paper is intended as an entry point for discussions and further about how to best carry out virtual crop modeling for the potato crop.