Climate Denial Crock of the Week

Not new results, but new to me.
Nevertheless worth knowing as we move into a growing season and possible El Nino step change in global temps.

NASA:

Climate change may affect the production of maize (corn) and wheat as early as 2030 under a high greenhouse gas emissions scenario, according to a new NASA study published in the journal, Nature Food. Maize crop yields are projected to decline 24%, while wheat could potentially see 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 greenhouse gas emissions. These changes would make it more difficult to grow maize 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 generation 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 maize 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 responses differ somewhat due to variations in their representations 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 part of the Agricultural Model Intercomparison and Improvement Project (AgMIP), an international partnership coordinated by Columbia University. The crop models simulate on a large scale how crops grow and respond to environmental conditions such as temperature, rainfall and atmospheric carbon dioxide, which are provided by the climate models. Each crop species’ behavior is based on their real life biological responses studied in indoor and outdoor lab experiments. In the end, the team created about 240 global climate-crop model simulations for each crop. By using multiple climate and crop models in various combinations, the researchers were more confident in their results.

“What we’re doing is driving crop simulations that are effectively growing virtual crops day-by-day, powered by a supercomputer, and then looking at the year-by-year and decade-by-decade change in each location of the world,” said Alex Ruane, co-director of the GISS Climate Impacts Group and a co-author of the study.

Nature – Climate impacts on global agriculture emerge earlier in new generation of climate and crop models:

Potential climate-related impacts on future crop yield are a major societal concern. .. Here we report new twenty-first-century projections using ensembles of latest-generation crop and climate models. Results suggest markedly more pessimistic yield responses for maize, soybean and rice compared to the original ensemble. Mean end-of-century maize productivity is shifted from +5% to −6% (SSP126) and from +1% to −24% (SSP585)—explained by warmer climate projections and improved crop model sensitivities. In contrast, wheat shows stronger gains (+9% shifted to +18%, SSP585), linked to higher CO₂ concentrations and expanded high-latitude gains. The ‘emergence’ of climate impacts consistently occurs earlier in the new projections—before 2040 for several main producing regions. While future yield estimates remain uncertain, these results suggest that major breadbasket regions will face distinct anthropogenic climatic risks sooner than previously anticipated.