Climate disruptions to agriculture expected to increase

New climate assessment report projects flooded rail lines, bigger and more frequent droughts and more hot nights.

A new full report of the National Climate Assessment released by the White House provides an in-depth look at climate change impacts on the U.S., and specifically outlines challenges for the agricultural sector and the need to further adapt to changing climate conditions in order to meet growing domestic and global food needs.

From record heat and severe drought to torrential downpours and sea level rise, states around the country are already feeling the effects of climate change, according to the newly released report. The report is a product of more than 240 experts from academia, the private sector, and local, state, and national government agencies.

Climate disruptions to agriculture have been increasing and are projected to become more severe over this century, the report notes. The report notes that while some U.S. regions and certain agricultural production will be resilient to climate change over the next 25 year or so, others will increasingly suffer from stresses due to extreme heat, drought, disease and heavy downpours.

The U.S. produces nearly $330 billion per year in agricultural commodities. This productivity is vulnerable to direct impacts on crop and livestock development and yield from changing climate conditions and extreme weather events, and indirect impacts through increasing pressures from pests and pathogens.

“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,” the report states.

The report explains that the annual maximum numbers of consecutive dry days (less than 0.01 inches of rain is projected to increase, especially in the western and southern parts of the nation, negatively affecting crop and animal production. “The trend toward more consecutive dry days and higher temperatures will increase evaporation and add stress to limited water resources, affecting irrigation and other water uses,” the report says.  

The agricultural sector continually adapts through a variety of strategies that have allowed previous agricultural production to increase, as evidenced by the continued growth in production and efficiency across the United States. “However, the magnitude of climate change projected for this century and beyond, particularly under higher emissions scenarios, will challenge the ability of the agriculture sector to continue to successful adapt,” the report states.

Hot nights – with a minimum temperature higher than 98% of the minimum temperatures between 1971 and 2002 – are projected to increase. High nighttime temperatures can reduce grain yields and increase stress on animals, resulting in reduced rates of meat, milk and egg production, the report adds.

The frost-free season is also expected to lengthen. The report identifies that by taking advantage of the increasing length of the growing season and changing planting dates could allow planting of more diverse crop rotations, which can be an effective adaptation strategy.

The report also looks specifically at different locations and identifies challenges climate change poses.

For instance, the Midwest’s agricultural lands, forests, Great Lakes, industrial activities, and cities are all vulnerable to climate variability and climate change. “Longer growing seasons and rising carbon dioxide levels increase yields of some crops, although these benefits have already been offset in some instances by occurrence of extreme events such as heat waves, droughts, and floods,” the highlights note.

The Great Plains region experiences multiple climate and weather hazards, including floods, droughts, severe storms, tornadoes, hurricanes, and winter storms. In much of the Great Plains, too little precipitation falls to replace that needed by humans, plants, and animals.

“These variable conditions already stress communities and cause billions of dollars in damage. Climate change will add to both stress and costs,” the report says. “Rising temperatures lead to increased demand for water and energy and impacts on agricultural practices.”

The report also outlines the many impacts on the reliability and capacity of the U.S. transportation system.

Extreme weather events currently disrupt transportation networks in all areas of the country; projections indicate that such disruptions will increase. “Climate change impacts will increase the total costs to the Nation’s transportation systems and their users, but these impacts can be reduced through rerouting, mode change, and a wide range of adaptive actions,” the report adds.

Many inland states, including Vermont, Tennessee, Iowa and Missouri, have experienced severe precipitation events, hail and flooding during the past three years, damaging roads, bridges and rail systems and the vehicles that use them.

“Over the coming decades, all modes of transportation and regions will be affected by increasing temperatures, more extreme weather events and changes in precipitation,” the report states.

The U.S. National Climate Assessment is available as an interactive, mobile-device-friendly, digital format on http://www.globalchange.gov/.

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