Similar estimates of temperature impacts on global wheat yield by three independent methods (original) (raw)

Yield reduction under climate warming varies among wheat cultivars in South Africa

Nature Communications

Understanding extreme weather impacts on staple crops such as wheat is vital for creating adaptation strategies and increasing food security, especially in dryland cropping systems across Southern Africa. This study analyses heat impacts on wheat using daily weather information and a dryland wheat dataset for 71 cultivars across 17 locations in South Africa from 1998 to 2014. We estimate temperature impacts on yields in extensive regression models, finding that extreme heat drives wheat yield losses, with an additional 24 h of exposure to temperatures above 30 °C associated with a 12.5% yield reduction. Results from a uniform warming scenario of +1 °C show an average wheat yield reduction of 8.5%, which increases to 18.4% and 28.5% under +2 and +3 °C scenarios. We also find evidence of differences in heat effects across cultivars, which suggests warming impacts may be reduced through the sharing of gene pools amongst wheat breeding programs.

Global wheat production with 1.5 and 2.0°C above pre‐industrial warming

Global Change Biology

Efforts to limit global warming to below 2°C in relation to the pre-industrial level are under way, in accordance with the 2015 Paris Agreement. However, most impact research on agriculture to date has focused on impacts of warming >2 o C on mean crop yields, and many previous studies did not focus sufficiently on extreme events and yield interannual variability. Here, with the latest climate scenarios from the Half a degree Additional warming, Prognosis and Projected Impacts (HAPPI) project, we evaluated the impacts of the 2015 Paris Agreement range of global warming (1.5 o C and 2.0 o C warming above the pre-industrial period) on global wheat production and local yield variability. A multi-crop and multiclimate model ensemble over a global network of sites developed by the Agricultural Model Intercomparison and Improvement Project (AgMIP) for Wheat was used to represent major rainfed and irrigated wheat cropping systems. Results show that projected global wheat production will change by-2.3% to 7.0% under the 1.5 o C scenario and-2.4% to 10.5% under the 2.0 o C scenario, compared to a baseline of 1980-2010, when considering changes in local temperature, rainfall and global atmospheric CO 2 concentration, but no changes in management or wheat cultivars. The projected impact on wheat production varies spatially; a larger increase is projected for temperate high rainfall regions than for moderate hot low rainfall and irrigated regions. Grain yields in warmer regions are more likely to be reduced than in cooler regions. Despite mostly positive impacts on global average grain yields, the frequency of extremely low yields (bottom 5 percentile of baseline distribution) and yield inter-annual variability will increase under both warming scenarios for some of the hot growing locations, including locations from the second largest global wheat producer-India, which supplies more than 14% of global wheat. The projected global impact of warming <2 o C on wheat production are therefore not evenly distributed and will affect regional food security across the globe as well as food prices and trade.

Temperatures and the growth and development of wheat: a review

We start by outlining the general effects of climatic variability and temperature extremes on wheat yields in the context of extreme event effects on crop processes for climatic impacts studies. We then review literature describing the responses of wheat plants to extreme temperatures. Cardinal temperature thresholds for different phenological processes in wheat are identified and we outline the effects of temperature on rates of growth and development. Finally, we assess the implications of the above for future climatic impact studies. Our summary shows how relatively small and consistent are the standard errors of the cardinal mean temperatures for many of the processes examined. Cardinal temperatures are conservative between studies and are seemingly well-defined in wheat. Into this category we put the lethal limits for wheat, the sterility response at anthesis, the cardinal temperatures for vernalization and some of the base and optimal temperatures. Important questions for the future involve the effects of combinations of extreme events and the modelling of specific effects such as the influence of high temperatures on grain set.

Effects of high-temperature episodes on wheat yields in New South Wales, Australia

Agricultural and Forest Meteorology, 2015

High-temperature episodes are known to be damaging to the reproductive mechanisms of crop plants such as wheat. This damage results in a decrease in wheat yields. This study used statistical modeling, three-dimensional (3-D) plots and the Agricultural Production System Simulator (APSIM) to analyze historical wheat yield records in southern New South Wales (NSW), Australia. The aim was to quantify the effects of reproductive stage high-temperature episodes on yields and to compare the predictions of the statistical model with those of APSIM. From the statistical model, it was found that high-degree hours (HDH), a measure of the number of hours that temperatures were above a threshold level during the reproductive stages, always had a negative effect on yields. Furthermore, growing season rainfall, up to approximately 30% above average, had a positive effect. Multi-variable analysis indicated that HDH had the largest negative effect when growing season rainfall was 5-45% below average. In the warmer/drier northwestern shires, there was an average 15% yearly yield reduction due to HDH. Over the whole area, there was an average 5.3% yield reduction for each 1 • C rise in growing season average daily temperature. Averaged across the six shires, high HDH values, which would normally be associated with reproductive system damage, did not affect the accuracy of the APSIM predictions. When the statistical model predictions and the APSIM simulation predictions were tested against a later independent set (1982-2008) of weather data and observed yield records, the predictions of the statistical model (RMSE = 14.6) were more accurate than those of APSIM (RMSE = 18.9). In conclusion, when suitable climate and yield datasets are available, a combination of statistical modeling and 3-D plots is a useful way to separate the effects of hightemperature episodes and rainfall on wheat yields and identify a rainfall range where high-temperature episodes are most damaging to yields.

Wheat Yield Responses to Rising Temperature: Insights from North Indian Plains of India

2021

Climate change and consequent variations in temperature pose a significant challenge for sustaining wheat production systems globally. In this study, the potential impact of rising temperature on wheat yield in the north Indian plains, India's major wheat growing region, was analyzed using panel data from the year 1981 to 2009. This study deviates from the majority of the previous studies by including non-climatic factors in estimating the impact of climate change. Two temperature measures were used for fitting the function, viz., Growing Season Temperature (GST) and Terminal Stage Temperature (TST), to find out the differential impact of increased temperature at various growth stages. Analysis revealed that there was a significant rise in both GST as well as TST during the study period. The magnitude of the annual increment in TST was twice that of GST. Wheat yield growth in the region was driven primarily by increased input resources such as fertilizer application and technolo...

Impacts of climate change on wheat in England and Wales

Journal of The Royal Society Interface, 2009

The frequency and magnitude of extreme weather events are likely to increase with global warming. However, it is not clear how these events might affect agricultural crops and whether yield losses resulting from severe droughts or heat stress will increase in the future. The aim of this paper is to analyse changes in the magnitude and spatial patterns of two impact indices for wheat: the probability of heat stress around flowering and the severity of drought stress. To compute these indices, we used a wheat simulation model combined with high-resolution climate scenarios based on the output from the Hadley Centre regional climate model at 18 sites in England and Wales. Despite higher temperature and lower summer precipitation predicted in the UK for the 2050s, the impact of drought stress on simulated wheat yield is predicted to be smaller than that at present, because wheat will mature earlier in a warmer climate and avoid severe summer drought. However, the probability of heat stress around flowering that might result in considerable yield losses is predicted to increase significantly. Breeding strategies for the future climate might need to focus on wheat varieties tolerant to high temperature rather than to drought.

Implications of 1.5 and 2.0°C additional warming for Wheat yield using a gridded modeling approach

Atmósfera, 2020

The goal of limiting the increasing global mean temperature below 2.0°C and possibly to 1.5°C, was decided in Paris Agreement in 2015. It is therefore important to understand the climate risk and impacts associated with 1.5°C and 2.0°C additional warming scenarios. The current study investigates the impacts of 1.5°C and 2.0°C additional warming on wheat yield in Pakistan using a gridded modeling approach. The generated climate data by four GCMs under 1.5°C and 2.0°C were acquired from the Half a degree Additional warming, Prognosis and Projected Impacts (HAPPI) scenarios group. The CERES-Wheat model was calibrated and evaluated using the field data and then applied to the entire region of Pakistan. Model calibration results showed a close association between observed and simulated wheat yield with an error ranging from 0.52 to 1.36%. Climate change projections indicated that the mean temperature is expected to rise by 0.46°C in 1.5°C and 1.44°C in 2.0°C additional warming scenarios in the GCMs. The spatial variations of precipitation ranges from-22.4 to 42.6% and 4.6 to 34.1% under 1.5°C and 2.0°C HAPPI scenarios, respectively. Higher precipitation was recorded in northern Pakistan as compared to central and southern Pakistan. The projected changes in temperature and precipitation will decrease the wheat yield by 3.2% and 4.7% in Punjab, 17.8% and 13.8% in Sindh province under 1.5°C and 2.0°C additional warming, respectively. However, the wheat yield will increase by 4.7% and 13% in KP, 9.4% and 15.3% in Baluchistan under 1.5°C and 2.0°C additional warming, respectively.