The Southeast—the Sunbelt—is a rapidly growing area of the United States. A great majority of this growth has occurred on the coastal areas of the region. It is expected to grow another 40 percent between now and 2025.
The Southeast is a very productive region of the country, supplying one-fourth of the United States's natural crops. Often referred to as the "wood basket," the region produces half of the country's timber supplies. It also produces a large portion of the nation's fish, poultry, tobacco, oil, coal, and natural gas. About half of the remaining wetlands in the lower 48 states are found in the Southeast; and more than 75 percent of the nation's annual wetland losses over the past 50 years occurred in this region. The region has a wide range of ecosystems, and species diversity is high.
Climate in the region varies on a decadal scale. The period from the 1920s to the 1940s was warm but was followed by a cool trend in the 1960s. Since the 1970s, temperatures have been increasing, with the
1990s temperatures as warm as the peaks in the 1920s and '30s. Annual rainfall has increased 30 percent or more over the past 100 years across Mississippi, Arkansas, South Carolina, Tennessee, Alabama, and parts of Louisiana. There have also been strong El Niño and La Niña effects in the region.
Climate model projections for this region using the Hadley model (a climate model developed by the United Kingdom's Hadley Centre for Climate Prediction and Research) scenario simulates less warming and a significant increase in precipitation of about 20 percent. Some of the climate models suggest that the rainfall associated with El Niño and the intensity of droughts during La Niña phases will be intensified as atmospheric CO2 increases.
There are several weather-related stresses on human populations in this region. Over the past 20 years, more than half of the nation's costliest weather-related disasters (such as hurricanes) have occurred in the Southeast. Across the region, intense precipitation has increased over the past 100 years, and this trend is projected to continue. There are also concerns about heat waves and drought. In 1998, there was a heat wave and drought that resulted in at least 200 deaths and caused damages in excess of $6 billion. Air quality is another major issue. As temperatures rise and increased emissions enter the atmosphere from power generation facilities, the ground-level ozone is increased, further degrading air quality. Increased flooding in low-lying coastal counties from the Carolinas to Texas is also likely to adversely affect human health—floods are the leading cause of death from natural disasters in the region and nationwide.
In the past, traditional ways to adapt included building structures such as flood levees, elevated structures (such as homes on stilts), and modifying building codes to account for flooding. Unfortunately, with global warming, this approach no longer provides adequate protection, especially in the coastal regions where sea-level rise continues to increase the likelihood of storm-surge flooding in virtually all southeastern coastal areas. It is crucial that these areas develop strategies for hazard preparedness in order to protect themselves from this very real threat.
Regarding agricultural crop yields, the lower Mississippi Valley and Gulf Coast areas are expected to have decreased yields, but the northern Atlantic Coastal Plain is expected to experience increased yields.
Neighborhoods in New Orleans, Louisiana, on September 2, 2005, remain flooded as a result of Hurricane Katrina. Rescue crews go into neighborhoods, looking for residents unable to get out of their houses. (jocelyn Augustino.FEMA)
In order to deal with possible negative impacts, producers have the option to switch crops or vary planting dates, patterns of water usage, crop rotations, and the amounts, timing, and application methods for fertilizers and pesticides. Models indicate that farmers, except those in the southern Mississippi Delta and Gulf Coast areas, will probably be able to mitigate most of the negative effects and possibly benefit from changes in CO2 and moisture, which enhance crop growth. Agriculture may also be helped through the development of improved varieties of crops designed to withstand changed weather conditions.
Forested areas of both pines and hardwoods are expected to increase productivity, mostly in the northern regions. Canadian models predict that savannas and grasslands due to decreased soil moisture and wildfire will replace part of these forests. Future management plans could include shifting timber harvesting northward in order to take stress off the forests in the southern reaches of the region. Other adaptation strategies include the use of more drought-hardy strains of pine and genetic improvements that could increase water use efficiency or water availability. Research and the creation of up-to-date forest management regimes are going to be important as the climate changes. As the climate gets hotter and drier, an aggressive fire management strategy will become critical.
Maintaining water quality is another important issue. Currently, water quality is challenged by intensive agricultural practices, urban development, coastal processes, and mining activities. As global warming progresses, these stresses on water quality will become even more pronounced. Higher temperatures will reduce the dissolved oxygen levels in the water. As flooding becomes more of a problem, floodwaters fouled with sewage, rotting farm animal carcasses, fuel, and chemicals swamping water treatment plants and contaminating public water supplies will become more common.
Storm surge damage in coastal areas due to sea-level rise will also become more of a problem. Projected impacts include: loss of barrier islands and wetlands that protect coastal communities from storm surges, reduced fisheries productivity as coastal marshes and submerged grassbeds are displaced or eliminated, and saltwater intrusion into surface and groundwater supplies. If there are changes in precipitation, it will alter the freshwater inflow into estuaries and alter the salinity patterns that determine the survival and distribution of coastal plant and animal communities.
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