The following changes in climatic conditions and impacts have been observed in the Southeast:
- Since 1970, the annual average temperature has risen about 2°F, with the greatest change occurring during the winter. The number of freezing days has declined by four to seven days per year for most of the region since the mid-1970s.
- Since 1901, there has been a 30 percent increase in precipitation during the fall (except in southern Florida). Summer and winter precipitation declined.
- There has been an increase in heavy downpours in many parts of the region.
- The percentage of the region experiencing moderate to severe drought increased over the past three decades.
- Barrier islands are losing land at an increasing rate, reducing their protective function.
- The destructive potential of Atlantic hurricanes has increased since 1970, correlated with an increase in sea surface temperature. A similar relationship with the frequency of hurricanes making landfall has not been established.
- An increase in average summer wave heights along the U.S. Atlantic coastline since 1975 has been attributed to a progressive increase in hurricane power.
The following climate-related changes are projected for the Southeast:
- Quality of life will be affected by increasing heat stress, water scarcity, and severe weather events.
- Warming in all seasons will continue and the rate of warming will increase through the end of the century.
- The greatest increases in temperature are expected in the summer, and the number of very hot days will increase at a greater rate than the average temperature. Average temperatures are projected to rise from between 4.5°F to about 9°F by the 2080s, depending upon the degree to which emissions are controlled.
- Higher temperatures will lead to an increased frequency, intensity, and duration of drought across the region.
- An increase in average sea level of up to two feet or more and the likelihood of increased hurricane intensity and associated storm surge are likely to be among the most costly consequences of climate change for this region. The intensity of Atlantic hurricanes is likely to increase this century with higher peak wind speeds, rainfall intensity, and storm surge.
- Increased intensity will further affect low-lying coastal ecosystems and coastal communities along the Gulf and South Atlantic coastal margin; increase inland and coastal flooding, coastal erosion rates, wind damage to coastal forests, and wetland loss; and exacerbate the risk to people, personal property, and public infrastructure.
- More frequent storm surge flooding and permanent inundation of coastal ecosystems and communities is likely in some low-lying areas, particularly along the central Gulf Coast where the land surface is sinking.
- The salinity of estuaries, coastal wetlands, tidal rivers, and shallow aquifers is likely to increase.
- Ecological thresholds are expected to be crossed throughout the region, causing major disruptions to ecosystems and to the benefits they provide to people.
- Decreased water availability due to increased temperature and longer periods of time between rainfall events, in addition to an increase in demand, is very likely to affect the region’s economy as well as its natural systems.
See National Climate Assessment: Southeast and Caribbean Regions
Find more resources on the Southeast Regional Resources List.