THE new full report of the U.S. 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 agriculture 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 rising sea levels, states around the country are already feeling the effects of climate change, according to the newly released report. Drought alone was estimated to cost the U.S. $50 billion from 2011 to 2013.
The report, "Climate Change Impacts in the United States," is a product of more than 240 experts from academia, the private sector and local, state and national government agencies.
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.
Climate disruptions to agriculture have been increasing and are projected to become more severe over this century (Maps), the report says. In addition, while some U.S. regions and certain agricultural production will be resilient to climate change over the next 25 years or so, others will increasingly suffer from stresses due to extreme heat, drought, disease and heavy downpours.
"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 number of consecutive dry days (less than 0.01 in. of rain) is projected to increase, especially in the western and southern parts of the nation, which will negatively affect 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 agriculture 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 U.S.
"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 successfully adapt," the report states.
The number of hot nights — with a minimum temperature higher than 98% of the minimum temperatures between 1971 and 2002 — is projected to increase. High nighttime temperatures can reduce grain yields and increase stress on animals, resulting in reduced meat, milk and egg production, the report adds.
The frost-free season is also expected to lengthen. The report notes that taking advantage of the lengthening growing season and changing planting dates could allow more diverse crop rotations to be planted, which can be an effective adaptation strategy.
The report also looks specifically at different locations and identifies the 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," according to the highlights.
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 what's needed by people, 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."
Unlike previous assessments, this report goes into much more detail on how climate change affects people.
William Hohenstein, director of the U.S. Department of Agriculture's Climate Change Program office, helped coordinate the rural communities chapter of the report and found that climate change will alter economic activities on which rural communities depend, such as agriculture, forestry and recreation.
"Rural communities are tremendously resilient but will face particular obstacles in responding to and preparing for climate change risks," Hohenstein said.
In a statement, Agriculture Secretary Tom Vilsack added that physical isolation, limited economic diversity and higher poverty rates in particular, combined with an aging population, increase the vulnerability of rural communities.
The report also outlines the many effects climate change has 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 says.
Many inland states, including Vermont, Tennessee, Iowa and Missouri, have experienced severe precipitation events, hail and flooding during the past three years that have damaged 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 www.globalchange.gov.