Monday, January 17

Global grain yield growth slows due to global warming Estimates by NARO

Among the major grains in the world, corn and soybean cannot meet food demand due to slowing of yield growth even if the temperature rise by the end of this century is less than 1.8 ℃. It was found by estimation by research groups such as. A research result suggesting the food crisis caused by global warming, the paper was recently published in the English scientific journal “Scientific Reports”.

The Paris Agreement, an international framework for the prevention of global warming, stipulates that the rise in global average temperature should be kept below 2 ° C, preferably below 1.5 ° C, by the end of this century. A research group consisting of Toshinao Iizumi, a researcher at the Agricultural Environmental Change Research Center of the Agricultural Research Organization, members of the International Center for Agriculture, Forestry and Fisheries, and the National Institute for Environmental Studies, said, “Intergovernmental Panel on Climate Change (IPCC). ) ”, We investigated the impact of global warming on the world’s major grain yields, assuming the four greenhouse gas emission scenarios used in the report.

In the survey, we used a numerical model that expressed the relationship between factors such as temperature and the growth process using mathematical formulas, and estimated the yield with a 50-kilogram mesh (mesh) around the world. The four scenarios are called “RCP (typical concentration pathway) 2.6”, “RCP4.5”, “RCP6.0” and “RCP8.5”. Based on these scenarios, the research group set the temperature rises up to the end of this century (2091-2100) at 1.8 ° C, 2.7 ° C, 3.2 ° C, and 4.9 ° C, respectively, compared to before the Industrial Revolution. Of the four scenarios, “RCP2.6” is the scenario in which the emission control measures of “peaking the peak of greenhouse gas emissions by 2100 and then decreasing” are pushed most strongly (low stabilization scenario).

Estimates for each of the four scenarios show that corn and soybean yield growth slows even if the temperature rise from pre-industrial to the end of this century is kept at 1.8 ° C based on the “RCP 2.6” scenario. Do you get it. For rice and wheat, it was found that the increase in yield began to stagnate when the temperature rise at the end of this century exceeded 3.2 ° C. If the temperature rise is less than 3.2 degrees Celsius, the average yield in the world will not be affected so much, but it may be adversely affected in low latitude areas.

According to the research group, global food demand is expected to reach about 1.6 times that of 2016 in 2050. In order to continuously increase the yield of the world’s major grains under climate change, the group has been able to withstand high temperatures in addition to the existing technology dissemination to developing countries such as fertilization management and the use of high-yielding varieties. The estimates indicate that it is necessary to accelerate the development and dissemination of more aggressive climate change adaptation technologies, such as the development of varieties, irrigation and drainage facilities.

Figure Changes in global average yield forecasts for major grains. The black line is the transition of the world average yield over the past 50 years (1961-2010) reproduced by the yield model, and the blue to green line is the transition of the yield forecast value in each emission scenario, both of which are the 2000s values. Relative value as the reference (1.0). The temperature rise is predicted by each emission scenario at the end of this century (2091-2100). The average values ​​of the reproduced and predicted values ​​of past yields are calculated every 10 years and shown as a line graph connecting them (the explanation and figures are provided by research groups such as the National Agriculture and Food Research Organization).Figure Changes in global average yield forecasts for major grains. The black line is the transition of the world average yield over the past 50 years (1961-2010) reproduced by the yield model, and the blue to green line is the transition of the yield forecast value in each emission scenario, both of which are the 2000s values. Relative value as the reference (1.0). The temperature rise is predicted by each emission scenario at the end of this century (2091-2100). For both the reproduced value and the predicted value of the past yield, the average value is calculated every 10 years and shown as a line graph connecting them (the figure explanation and the figure are provided by the research group such as NARO).