Washington — The U.S. Climate
Change Science Program (CCSP) today released "Synthesis and Assessment
Product 4.3 (SAP 4.3): The Effects of
Climate Change on Agriculture, Land Resources, Water Resources, and
Biodiversity in the United States." The CCSP
integrates the federal research efforts of 13 agencies on climate and global
change. Today's report is one of the most extensive examinations of climate
impacts on U.S. ecosystems. USDA is
the lead agency for this report and coordinated its production as part of its
commitment to CCSP.
report issued today provides practical information that will help land owners
and resource managers make better decisions to address the risks of climate
change," said Agriculture Chief Economist Joe Glauber.
was written by 38 authors from the universities, national laboratories,
non-governmental organizations, and federal service. The report underwent
expert peer review by 14 scientists through a Federal Advisory Committee
formed by the USDA. The National Center for Atmospheric
Research also coordinated in the production of the report. It is posted on
the CCSP Web site at:
finds that climate change is already affecting U.S. water resources,
agriculture, land resources, and biodiversity, and will continue to do so.
Specific findings include:
- Grain and oilseed crops will
mature more rapidly, but increasing temperatures will increase the risk
of crop failures, particularly if precipitation decreases or becomes
- Higher temperatures will
negatively affect livestock. Warmer winters will reduce mortality but
this will be more than offset by greater mortality in hotter summers.
Hotter temperatures will also result in reduced productivity of
livestock and dairy animals.
- Forests in the interior West,
the Southwest, and Alaska are already being affected
by climate change with increases in the size and frequency of forest
fires, insect outbreaks and tree mortality. These changes are expected
- Much of the United States has experienced higher
precipitation and streamflow, with decreased drought severity and
duration, over the 20th century. The West and Southwest, however, are
notable exceptions, and increased drought conditions have occurred in
- Weeds grow more rapidly under
elevated atmospheric CO2. Under projections reported in the assessment,
weeds migrate northward and are less sensitive to herbicide
- There is a trend toward
reduced mountain snowpack and earlier spring snowmelt runoff in the Western United States.
- Horticultural crops (such as
tomato, onion, and fruit) are more sensitive to climate change than
grains and oilseed crops.
- Young forests on fertile
soils will achieve higher productivity from elevated atmospheric CO2
concentrations. Nitrogen deposition and warmer temperatures will
increase productivity in other types of forests where water is
- Invasion by exotic grass
species into arid lands will result from climate change, causing an
increased fire frequency. Rivers and riparian systems in arid lands will
be negatively impacted.
- A continuation of the trend
toward increased water use efficiency could help mitigate the impacts of
climate change on water resources.
- The growing season has
increased by 10 to 14 days over the last 19 years across the temperate latitudes.
Species' distributions have also shifted.
- The rapid rates of warming in
the Arctic observed in recent decades,
and projected for at least the next century, are dramatically reducing
the snow and ice covers that provide denning and foraging habitat for
USDA agencies are responding to the risks of
climate change. For example, the Forest Service is incorporating climate
change risks into National Forest Management Plans and is providing guidance
to forest managers on how to respond and adapt to climate change. The Natural
Resources Conservation Service and Farm Services Agency are encouraging
actions to reduce greenhouse gas emissions and increase carbon sequestration
through conservation programs. USDA's Risk Management Agency has prepared
tools to manage drought risks and is conducting an assessment of the risks of
climate change on the crop insurance program.