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In the coming decades, Alabama will become warmer, and the state
will probably experience more severe floods and drought. Unlike
most of the nation, Alabama has not become warmer during the last
50 years. But soils have become drier, annual rainfall has increased
in most of the state, more rain arrives in heavy downpours, and sea
level is rising about one inch every eight years. Changing the climate
is likely to increase damages from tropical storms, reduce crop
yields, harm livestock, increase the number of unpleasantly hot days,
and increase the risk of heat stroke and other heat-related illnesses.
Our climate is changing because the earth is warming. People have
increased the amount of carbon dioxide in the air by 40 percent
since the late 1700s. Other heat-trapping greenhouse gases are also
increasing. These gases have warmed the surface and lower atmo-
sphere of our planet about one degree (F) during the last 50 years.
Evaporation increases as the atmosphere warms, which increases
humidity, average rainfall, and the frequency of heavy rainstorms
in many places-but contributes to drought in others. While most
of the earth warmed, natural cycles and sulfates in the air cooled
Alabama. Sulfates are air pollutants that reflect sunlight back into
space. Now sulfate emissions are declining, and the factors that
once prevented the state from warming are unlikely to persist.
Greenhouse gases are also changing the world's oceans and ice
cover. Carbon dioxide reacts with water to form carbonic acid, so
the oceans are becoming more acidic. The surface of the ocean
has warmed about one degree during the last 80 years. Warming
is causing snow to melt earlier in spring, and mountain glaciers are
retreating. Even the great ice sheets on Greenland and Antarctica
are shrinking. Thus the sea is rising at an increasing rate.
Temperature change (*F):
-1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5
Changing temperatures in the last century. While most of the nation
has warmed, Alabama and a few other states have cooled. Source:
EPA, Climate Change Indicators in the United States.
Rising Seas and Retreating Shores
Sea level is rising more rapidly in Alabama than most
coastal areas because the land is sinking. If the oceans
and atmosphere continue to warm, sea level along the
Alabama coast is likely to rise eighteen inches to four feet
in the next century. Rising sea level submerges wetlands
and dry land, erodes beaches, and exacerbates coastal
flooding.
Coastal Storms, Homes, and Infrastructure
Tropical storms and hurricanes have become more
intense during the past 20 years. Although warming
oceans provide these storms with more potential energy,
scientists are not sure whether the recent intensification
reflects a long-term trend. Nevertheless, hurricane wind
speeds and rainfall rates are likely to increase as the
climate continues to warm.
Whether or not storms become more intense, coastal
homes and infrastructure will flood more often as sea
level rises, because storm surges will become higher as
well. Rising sea level is likely to increase flood insurance
rates, while more frequent storms could increase the
deductible for wind damage in homeowner insurance
policies. Many cities, roads, railways, ports, airports, and
oil and gas facilities along the Gulf Coast are vulnerable
to the combined impacts of storms and sea level rise.
People may move from vulnerable coastal communities
and stress the infrastructure of the communities that
receive them.
- - I g ~
Hurricane Katrina's storm surge destroyed homes and roads on
Dauphin Island in 2005. Credit: FEMA.
