Displacement of People
The United Nations estimates that by the year 2050, 150 million people will
need to be relocated worldwide. This will occur because of the effects of coastal
flooding, shoreline erosion, and agricultural disruption.
Ecological Productivity
Satellite photos have shown that ecological productivity in the Northern
Hemisphere has increased since 1982. In the tropics, plants increase productivity
more so than older trees (which are carbon sinks).
Forest Fires
Boreal forest fires in North America used to average 2.5 million acres (10,000 sq
km). They now average 7 million acres (28,000 sq km). Current forest
management practices may also be contributing to the increase.
Glacier Melting
The total surface area of glaciers worldwide has decreased 50% since the end of
the 19th century. Glacier melting causes: ■ Landslides
■ Flash floods ■ Glacial lake overflow ■ Increased variation in the water
flows into rivers ■ The displacement of people (e.g., the Hindu Kush and
Himalayan glacier melts are reliable water sources for people living in
China, India, and much of Asia—without glacier melt, water for
agriculture and hydroelectric production in these areas would be seriously
impacted) The main ice-covered landmass is Antarctica at the South Pole,
with about 90% of the world’s ice and 70% of its freshwater. Antarctica is
covered with ice that is an average of about 7,000 feet (2,000 m) thick. If
all of the Antarctic ice melted, sea levels around the world would rise
about 200 feet (60 m).
At the North Pole, the ice is not nearly as thick as it is at the South Pole, and
it floats on the Arctic Ocean. If it melted, sea levels would not be affected—
remember, melting ice only raises the level of seawater if it does not float in the
water. There is a significant amount of ice covering Greenland, which would add
another 20 feet (7 m) to the oceans if it melted. Since Greenland is closer to the
equator than Antarctica is, the temperatures are higher, so that ice is more likely
to melt.
Compounding the problem of melting ice from land raising sea levels is the
phenomenon of thermal expansion of water (as water gets warmer, water
molecules move further apart, increasing the ocean’s volume).