Miller Magazine Issue: 152 August 2022

61 COVER STORY MILLER / AUGUST 2022 other inputs which become the food we eat – is produced significant distances from where it is consumed; before ar- riving on supermarket shelves it is traded on international markets and travels through global supply chains. In this way, achieving global food security involves a broad range of interdependent activities all around the world, including the stability of markets, which allows food to be purchased at affordable prices. CLIMATE RISKS TO STAPLE CROPS Since agriculture began approximately 10,000 years ago, grains have provided the main source of calories for the human diet. Recognized for their high yields, nutritional val- ue, and ease of transport and storage, a range of different grains were domesticated by the world’s original farmers. Wheat, rice, maize, barley, sorghum, millet, and root crops still constitute the basis of human nutrition worldwide. Staple crops maize, rice and wheat are consumed world- wide as an integral part of the daily diet of billions of people. Changes in the price and availability of these commodities directly affect peoples’ food and nutritional security. Changes in commodity prices are easy to track and rapidly and directly influence the price consumers pay at market. These staple crops tend to be produced via heavily mechanized commer- cial agriculture and traded on global markets. Climate risks to these commodities are therefore a matter of international and national government policy, national security and high politics. CLIMATE CHANGE IMPACT ON CROPS EXPECTED WITHIN 10 YEARS Climate change may affect the production of corn and wheat as early as 2030 under a high greenhouse gas emissions scenario, according to a NASA study published in the journal, Nature Food. Corn crop yields are project- ed to decline 24%, while wheat could potentially see a growth of about 17%. Using advanced climate and agricultural models, scientists found that the change in yields is due to projected increases in temperature, shifts in rainfall patterns, and elevated surface carbon dioxide concentrations from human-caused green- house gas emissions. These changes would make it more difficult to grow corn in the tropics, but could expand wheat’s growing range. “We did not expect to see such a fundamental shift, as compared to crop yield projections from the previous gen- eration of climate and crop models conducted in 2014,” said lead author Jonas Jägermeyr, a crop modeler and climate scientist at NASA’s Goddard Institute for Space Studies (GISS) and The Earth Institute at Columbia University in New York City. The projected corn response was surprisingly large and negative, he said. “A 20% decrease from current production levels could have severe implications worldwide.” To arrive at their projections, the research team used two sets of models. First, they used climate model simulations from the international Climate Model Intercomparison Project-Phase 6 (CMIP6). Each of the five CMIP6 climate models used for this study runs its own unique response of Earth’s atmosphere to greenhouse gas emission scenarios through 2100. These re- sponses differ somewhat due to variations in their representa- tions of the Earth's climate system. Then the research team used the climate model simulations as inputs for 12 state-of-the-art global crop models that are