The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here:

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Kimberly Nicholas

Kimberly Nicholas

Senior Lecturer, Docent

Kimberly Nicholas

How Climate Change Affects Extremes in Maize and Wheat Yield in Two Cropping Regions


  • Caroline C. Ummenhofer
  • Hong Xu
  • Tracy E. Twine
  • Evan H. Girvetz
  • Heather R. McCarthy
  • Netra Chhetri
  • Kimberly Nicholas

Summary, in English

Downscaled climate model projections from phase 5 of the Coupled Model Intercomparison Project (CMIP5) were used to force a dynamic vegetation agricultural model (Agro-IBIS) and simulate yield responses to historical climate and two future emissions scenarios for maize in the U.S. Midwest and wheat in southeastern Australia. In addition to mean changes in yield, the frequency of high- and low-yield years was related to changing local hydroclimatic conditions. Particular emphasis was on the seasonal cycle of climatic variables during extreme-yield years and links to crop growth. While historically high (low) yields in Iowa tend to occur during years with anomalous wet (dry) growing season, this is exacerbated in the future. By the end of the twenty-first century, the multimodel mean (MMM) of growing season temperatures in Iowa is projected to increase by more than 5 degrees C, and maize yield is projected to decrease by 18%. For southeastern Australia, the frequency of low-yield years rises dramatically in the twenty-first century because of significant projected drying during the growing season. By the late twenty-first century, MMM growing season precipitation in southeastern Australia is projected to decrease by 15%, temperatures are projected to increase by 2.8 degrees-4.5 degrees C, and wheat yields are projected to decline by 70%. Results highlight the sensitivity of yield projections to the nature of hydroclimatic changes. Where future changes are uncertain, the sign of the yield change simulated by Agro-IBIS is uncertain as well. In contrast, broad agreement in projected drying over southern Australia across models is reflected in consistent yield decreases for the twenty-first century. Climatic changes of the order projected can be expected to pose serious challenges for continued staple grain production in some current centers of production, especially in marginal areas.


  • LUCSUS (Lund University Centre for Sustainability Studies)
  • BECC: Biodiversity and Ecosystem services in a Changing Climate

Publishing year







Journal of Climate





Document type

Journal article


American Meteorological Society


  • Climate Research




  • ISSN: 1520-0442