Climate-related disruptions to fruit and vegetable growers will increase over the next 25 years, according to projections from the third National Climate Assessment.
The 840-page report, (www.globalchange.gov), was written by 240 groups of authors who documented ways climate change is affecting agriculture, forestry and other sectors. Congress calls for the assessment every four years through the U.S. Global Change Research Program.
“Many agricultural regions will experience declines in crop and livestock production from increased stress due to weeds, diseases, insect pests, and other climate change induced stresses,” said William Hohensein, director of the USDA’s Climate Change Program Office, in a blog post about the report. By 2050, climate change will increasingly effect most crops and livestock, he said.
Hohensein said extremes in precipitation will challenge dryland and irrigated agriculture, potentially resulting in loss and degradation of soil and water resources unless new conservation methods are implemented.
Growers often try to survive current crop challenges and may not have the luxury of planning for long-term climate change, said Ray Gilmer, vice president of issues management and communication for the Washington, D.C.-based United Fresh Produce Association. Gilmer said water is a dominant issue for California growers.
“If they don’t get the water problem solved, the long-term challenge isn’t anything they can necessarily need to worry about because they might not be in business any more,” he said.
According to the report, there are “multiple lines of independent evidence” that confirm that human activities are the primary cause of the global warming of the past 50 years. Burning of coal, oil, and gas, and clearing of forests have boosted carbon dioxide levels in the atmosphere by more than 40% since the Industrial Revolution, according to the report. The U.S. average temperature has increased by 1.3°F to 1.9°F since 1895, and most of this increase has occurred since 1970.
Temperatures are projected to rise another 2°F to 4°F in most areas of the U.S. in the next few decades, and by 2100 temperatures could rise by 3°F to 5°F under a lower emissions scenario and as much as a 5°F to 10°F rise for a higher emissions scenario, according to the report.
In California, the combination of a longer frost-free season, less frequent cold air outbreaks, and more frequent heat waves will accelerate crop ripening and maturity, reduce yields of corn, tree fruit, and wine grapes and increase irrigation use.
“This combination of climate changes is projected to continue and intensify, possibly requiring a northward shift in crop production, displacing existing growers and affecting farming communities,” according to the report.
Challenges to agriculture include:
- Production declines because of increases in weeds, diseases and insects;
- Erosion and degradation of soil;
- Fruit trees that require chill hours to set a good crop will see production declines. requiring new varieties;
- Weather extremes will negatively affect crop and livestock productivity; and
- Increased innovation will be needed to keep pace with climate change over the next 25 years.