Average
global temperature has increased by almost 1ºF
over the past century; scientists expect the average global temperature
to increase an additional 2 to 6ºF over the next one hundred
years. This may not sound like much, but it could change the Earth's
climate
as never before. At the peak of the last ice age (18,000 years ago),
the temperature was only 7ºF colder than it is today, and glaciers
covered much of North America!
Even
a small increase in temperature over a long time can change the
climate. When the climate changes, there may be big changes in the
things that people depend on. These things include the level of
the oceans and the places where we plant crops. They also include
the air we breathe and the water we drink.
What
Might Happen? It is important
to understand that scientists don't know for sure what climate change
will bring. Some changes brought about by climate change will be
good. If you live in a very cool climate, warmer temperatures might
be welcome. Days and nights could be more comfortable and people
in the area may be able to grow different and better crops than
they could before. But it is also true that changes in some places
will not be very good at all.
Climate
change may affect people's health both directly and indirectly.
For example, heat
stress and other heat related health problems are caused directly
by very warm temperatures and high humidity. Untreated, heat stress
can be a very serious medical problem. Scientists suspect that,
in many places, climate change will increase the number of very
hot days that occur during the year. More hot days increases the
possibility of heat related health problems.
Indirectly,
ecological
disturbances, air pollution, changes in food and water supplies,
and coastal flooding are all examples of possible impacts that might
affect human health.
How
people and nature adapt to climate change will determine how seriously
it impacts human health. Some people and places are likely to be
affected more than others. Generally, poor people and poor countries
are less likely to have the money and resources they need to cope
with preventing and treating health problems. Very young children
and the elderly adults will run the highest risks.
Climate
change may alter the world's habitats
and ecosystems
all living things are included in and rely on these places.
Many of these places depend on a delicate balance of rainfall, temperature,
and soil type. A rapid change in climate could upset this balance
and seriously endanger many living things.
Most
past climate changes occurred slowly, allowing plants and animals
to adapt to the new environment
or move somewhere else. However, if future climate changes occur
as rapidly as some scientists predict, plants and animals may not
be able to react quickly enough to survive. The ocean's ecosystems
also could be affected for the same reasons.
Global
warming may make the sea level become higher. Why? Well, warmer
weather
makes glaciers melt. A glacier is a large sheet of ice that moves
very, very slowly. Some melting glaciers add more water to the ocean.
Warmer temperatures also make water expand. When water expands in
the ocean, it takes up more space and the level of the sea rises.
Sea
level may rise between several inches and as much as 3 feet during
the next century. This will effect both natural systems and manmade
structures along coastlines. Coastal flooding could cause saltwater
to flow into areas where salt is harmful, threatening plants and
animals in those areas. For example, an increase in the salt content
of the Delaware and Chesapeake bays is thought to have decreased
the number of oysters able to live in those waters.
Oceanfront
property would be affected by flooding, and beach erosion could
leave structures even more vulnerable to storm waves. Whether we
move back from the water or build barricades
in the face of a rising sea, it could cost billions of dollars to
adapt to such change. Coastal flooding also may reduce the quality
of drinking water in coastal areas.
Global
warming may make the Earth warmer in cold places. People living
in these places may have a chance to grow crops in new areas. But
climate change also might bring droughts
to other places where we grow crops. In some parts of the world,
people may not have enough to eat because they cannot grow the food
that they need.
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