On Wednesday, the U.S. Climate Change Science Program released an in-depth report on how climate changes are impacting U.S. ecosystems. Don't let the title scare you from exploring it.
Titled "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", it combines research efforts of 13 federal agencies on climate and global change. It's posted on the CCSP Web site at:
Climate change is already affecting U.S. water resources, agriculture, land resources and biodiversity. And, it'll continue to do so. Specific findings include:
- Grain and oilseed crops will mature more rapidly. (Growing degree days are accumulating faster.) But increasing temperatures will increase the risk of crop failures, particularly if precipitation decreases or becomes more variable.
- The growing season has increased by 10 to 14 days over the last 19 years across the temperate latitudes. Species' distributions have also shifted.
- 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. That's why increasing focus on animal comfort pays dividends.
- 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 to continue.
- Much of the U.S. has experienced higher precipitation and streamflow, with decreased drought severity and duration, over the 20th century. The West and Southwest, however, are notable exceptions.
- Weeds grow more rapidly under elevated atmospheric CO2. Under projections reported in the assessment, weeds migrate northward and are less sensitive to herbicide applications. Kudzu, an overwintering carrier of Asian soybean rust, is a prime example.
- 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 available.
- 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.