Abstract: The frequency and intensity of extreme high temperature events are expected to increase with climate change. Higher temperatures near anthesis have a large negative effect on maize (Zea mays, L.) grain yield. While crop growth models are commonly used to assess climate change impacts on maize and other crops, it is only recently that they have accounted for such heat stress effects, despite limited field data availability for model evaluation. There is also increasing awareness but limited testing of the importance of canopy temperature as compared to air temperature for heat stress impact simulations. In this study, four independent irrigated field trials with controlled heating imposed using polyethylene shelters were used to develop and evaluate a heat stress response function in the crop modeling framework SIMPLACE, in which the Lintul5 crop model was combined with a canopy temperature model. A dataset from Argentina with the temperate hybrid Nidera AX 842 MG (RM 119) was used to develop a yield reduction function based on accumulated hourly stress thermal time above a critical temperature of 34 degrees C. A second dataset from Spain with a FAO 700 cultivar was used to evaluate the model with daily weather inputs in two sets of simulations. The first was used to calibrate SIMPLACE for conditions with no heat stress, and the second was used to evaluate SIMPLACE under conditions of heat stress using the reduction factor obtained with the Argentine dataset. Both sets of simulations were conducted twice; with the heat stress function alternatively driven with air and simulated canopy temperature. Grain yield simulated under heat stress conditions improved when canopy temperature was used instead of air temperature (RMSE equal to 175 and 309 g m(-2), respectively). For the irrigated and high radiative conditions, raising the critical threshold temperature for heat stress to 39 degrees C improved yield simulation using air temperature (RMSE: 221 gm(-2)) without the need to simulate canopy temperature (RMSE: 175 gm(-2)). However, this approach of adjusting thresholds is only likely to work in environments where climatic variables and the level of soil water deficit are constant, such as irrigated conditions and are not appropriate for rainfed production conditions. (C) 2016 Elsevier B.V. All rights reserved.

Abstract: The FACCE MACSUR kickoff meeting took place 15-16 October 2012 in Berlin, Germany. The date for the meeting was moved from July to October to accommodate the participation of most institutions involved in MACSUR in a sufficiently large meeting place. One hundred and forty-five persons participated in the event. The meeting was organized as a workshop to allow for expanded time for interaction among the participants of the 73 involved institutions. The keynote lectures by Tim Benton (Global Food Security and University of Leeds) and Tim Carter (Finnish Environment Institute – SYKE) set the background by describing the need for assessing future impacts on food security and how to deal with the uncertainty associated with data, models, and projections. In parallel sessions participants discussed the organization of the work in the project and in each Theme, common approaches to answering the questions, selection of scenarios, involvement of stakeholders, and how the results will be presented. The results of the four cross-cutting workshops are documented in separate reports (M-H3.3.1 through M-H3.3.4) and serve as the starting point for more detailed planning over the following months.A post-hoc survey filled in by 75 attendees showed that the workshop had answered many organizational issues. But since the project has only started, many more issues must be discussed and clarified in the coming months, the survey showed. Overall, two thirds of the participants were satisfied with the organization oft he workshop. No Label