EFFECTS OF GLOBAL WARMING

EFFECTS OF GLOBAL WARMING

The predicted effects of global warming on the environment and for human life are

numerous and varied. It is generally difficult to attribute specific natural

phenomena to long-term causes, but some effects of recent climate change may already

be occurring. Rising sea levels, glacier retreat, Arctic shrinkage, and altered

patterns of agriculture are cited as direct consequences, but predictions for

secondary and regional effects include extreme weather events, an expansion of

tropical diseases, changes in the timing of seasonal patterns in ecosystems, and

drastic economic impact. Concerns have led to political activism advocating

proposals to diminish, eliminate, or adapt to it.

The probability of one or more of these changes occurring is likely to increase with

the rate, magnitude, and duration of climate change. Additionally, the United States

National Academy of Sciences has warned, "greenhouse warming and other human

alterations of the earth system may increase the possibility of large, abrupt, and

unwelcome regional or global climatic events. Future abrupt changes cannot be

predicted with confidence, and climate surprises are to be expected."

The USNAS finds that the effects of global warming will be mixed across regions. For

smaller values of warming (1 to 3 °C), changes are expected to produce net benefits

in some regions and for some activities, and net costs for others. Greater warming

is very likely to produce net costs (or to reduce the benefits from smaller warming)

in all regions. Developing countries are expected to be especially vulnerable to

reduced economic growth as a result of warming.

Most of the consequences of global warming would result from one of three physical

changes: sea level rise, higher local temperatures, and changes in rainfall

patterns. Sea level is generally expected to rise 18 to 59 cm (7.1 to 23.2 inches)

by the end of the century.