Farmers and ranchers in the West will be pressed to adapt to minimize losses as temperatures rise by several degrees over the next few decades, according to the Fourth National Climate Assessment.
Average annual temperatures in the Northwest have increased nearly 2 degrees Fahrenheit since 1900. Temperatures are projected to rise 2.3 to 11 degrees by the late 21st century. The outcome depends on future greenhouse gas emissions, according to the federal study led by the National Oceanic and Atmospheric Administration and released Nov. 23.
The report catalogs the potential pitfalls of higher temperatures, such as less water and forage, more weeds and insects and overheated livestock.
Longer growing season
The assessment, however, notes that farmers and nature adapt. Plants and livestock can be bred to withstand higher temperatures. Dryland wheat yields, for example, are expected to rise as growers shift planting dates and plants use water more efficiently.
Average growing seasons have increased in the West by nearly two weeks since the beginning of the 20th century. The growing season has become shorter in a few southeastern states.
“Risks associated with climate change depend on the rate and severity of the change and the ability of producers to adapt to changes,” according to the report’s summary on agriculture. “These adaptations include altering what is produced, modifying the inputs used for production, adopting new technologies, and adjusting management strategies.”
The report was the second half of a quadrennial national assessment on climate change. The first half was released last year and focused on how higher temperatures are affecting the earth. Volume II surveys the effects on human health, the economy and society.
Northwest livestock producers should fare better than ranchers in hotter regions. Still, production costs probably will rise because animals will need more water and have less forage, according to the report.
Dairy cows are particularly sensitive to higher temperatures because heat reduces their appetite. Dairies everywhere are expected to lose production. Losses in the Pacific Northwest are expected to be small compared to the Southeast and Southern Plains.
Sea levels are expected to rise and threaten coastal towns. At the high end, sea levels are projected to rise by as much as 8 feet by 2100. A “very likely range” is between 1 foot and 4 feet, according to the assessment. So far, the annual median sea level has risen 9 inches since the early 20th century.
Climate change may shift where plants grow best. Northwest wine producers may be able to produce higher-value grapes, providing they’re able to get water.
The assessment warns that over the long term the number of severely hot days will reduce premium wine grape production in the Northwest. Vineyards may need to move north.
The assessment warns the Northwest’s 2015 snowpack provided a preview of may become “more commonplace” and cites a study led by the Oregon Climate Change Research Institute at Oregon State University.
According to the study’s abstract, the low snowpack in Oregon and Washington that winter was more due to unusually warm sea-surface temperatures than human influence.
The Palmer Drought Severity Index, a measure of temperatures and precipitation, shows “no detectable change in long-term U.S. drought statistics,” according to the assessment.
Still, the specter of drought hangs over the assessment. Irrigators who rely on surface water will be particularly vulnerable, according to the report.
As is the case now, farmers with junior water rights will be more affected than growers with senior water rights. A more “robust” market for buying and selling water rights may help agriculture adapt, the assessment states.