Some conference speakers presented data showing that in general, the first fall freeze is coming later and the last spring freeze is coming earlier.
Even with evidence of earlier frost-free dates in the spring, however, farmers have to gauge the risk – if they plant early, they can still end up with the devastation of a killing freeze, said Stacy Hutchinson, professor of biological and agricultural engineering at K-State.
In most crops so far, there’s been a negative impact on yields from the changes occurring in the climate, Rice said, adding that yields have generally gone up in Kansas because of the development of better varieties, better management and better equipment. But there’s more variability in growing conditions.
“Every one of these dips has been related to weather,” said Rice as he displayed a chart showing crop yield trends. “Irrigation can moderate that, but can’t make up for the whole impact of the variability.”
Diseases that infect plants can be an indicator of climate change, said Karen Garrett, who is a plant pathologist at K-State. She gave the example of soybean rust, a disease that she and a team of researchers are currently studying. Soybean rust overwinters in the south and infects soybean plants as it moves north during the warmer months of the growing season. What happens if overwintering for diseases like this becomes easier farther north?
Rice, who served on the United Nations Intergovernmental Panel on Climate Change, provided the IPCC report’s projected changes for the climate of the U.S. Midwest, including fewer extreme high temperatures in summer in the short term, but more in the long term, as well as higher nighttime temperatures in both summer and winter. The report also predicted increased temperature variability.
The IPCC report also projected about 10 percent more precipitation annually in the Midwest, as well as a change in seasonality. Most of the increase in precipitation is expected to come in the first half of the year, meaning wetter springs and drier summers. There is also more variability in summer precipitation expected, including more intense rain events which could mean more runoff.
Rice said changes in agriculture practices have the potential to make a significant impact on climate change. As a soil scientist, he studies carbon sequestration – the process of transforming carbon in the air (carbon dioxide, or CO2) into stored soil carbon. Carbon dioxide is taken up by plants through photosynthesis, and incorporated into living plant matter. As the plants die, the carbon-based leaves, stems, and roots decay in the soil and become soil organic matter.