Name _______________________
Date __________
Signs and Consequences of Global Warming
Unless we act now, our children will inherit a hotter world, dirtier air and
water, more severe floods and droughts, and more wildfires. The latest scientific
data confirm that the earth's climate is rapidly changing. Global temperatures
increased by about 1 degree Fahrenheit over the course of the last century, and
will likely rise even more rapidly in coming decades. The cause? A thickening
layer of carbon dioxide pollution, mostly from power plants and automobiles, that
traps heat in the atmosphere.
Scientists say that unless global warming emissions are reduced, average
U.S. temperatures could rise another 3 to 9 degrees by the end of the century -with far-reaching effects. Sea levels will rise, flooding coastal areas. Heat waves
will be more frequent and more intense. Droughts and wildfires will occur more
often. Disease-carrying mosquitoes will expand their range. And species will be
pushed to extinction. As this article shows, many of these changes have already
begun.
CLIMATE PATTERN CHANGES
Consequence: warmer temperatures
Average temperatures will rise, as will the frequency of heat waves.
Warning signs today

Most of the United States has already warmed, in some areas by as much
as 4 degrees Fahrenheit. In fact, no state in the lower 48 states
experienced below average temperatures in 2002. The last three five-year
periods are the three warmest on record.

Many places in North America had their hottest seasons or days on record
in the late 1990s.

Since 1980, the earth has experienced 19 of its 20 hottest years on
record, with 2005 and 1998 tied for the hottest and 2002 and 2003 coming
in second and third.
Consequence: drought and wildfire
Warmer temperatures could also increase the probability of drought. Greater
evaporation, particularly during summer and fall, could exacerbate drought
conditions and increase the risk of wildfires.
Warning signs today

The 1999-2002 national drought was one of the three most extensive
droughts in the last 40 years.
Adapted from http://www.nrdc.org/globalWarming/fcons.asp

In 2002, the Western United States experienced its second worst wildfire
season in the last 50 years; more than 7 million acres burned. Colorado,
Arizona, and Oregon had their worst seasons.

The period from April through June of 1998 was the driest three-month
period in 104 years in Florida, Texas, and Louisiana.

Dry conditions produced the worst wildfires in 50 years in Florida in 1998.

April through July of 1999 was the driest four-month stretch in 105 years
of record-keeping in New Jersey, Delaware, Maryland, and Rhode Island.

Montana, Colorado, and Kansas experienced severe dust storms in 2002,
a product of dry conditions.

September 2001 to February 2002 was the second driest six-month period
on record for the Northeast.
Consequence: more intense rainstorms
Warmer temperatures increase the energy of the climatic system and lead to
more intense rainfall at some times and in some areas.
Warning signs today

National annual precipitation has increased between 5 and 10 percent
since the early 20th century, largely the result of heavy downpours in
some areas.

Vermont, New Hampshire, Rhode Island, and Massachusetts each got
more than double their normal monthly rainfall in June 1998.

Severe flooding in the Texas, Montana, and North Dakota during the
summer of 2002 caused hundreds of millions of dollars in damage.
HEALTH EFFECTS
Consequence: deadly heat waves and the spread of disease
More frequent and more intensive heat waves could result in more heat-related
deaths. These conditions could also aggravate local air quality problems, already
afflicting more than 80 million Americans. Global warming is expected to increase
the potential geographic range and virulence of tropical diseases as well.
Warning signs today

In 2003, extreme heat waves caused more than 20,000 deaths in Europe
and more than 1500 deaths in India.
Adapted from http://www.nrdc.org/globalWarming/fcons.asp

More than 250 people died as a result of an intense heat wave that
gripped most of the eastern two-thirds of the United States in 1999.

Disease-carrying mosquitoes are spreading as climate shifts allow them to
survive in formerly inhospitable areas. Mosquitoes that can carry dengue
fever viruses were previously limited to elevations of 3,300 feet but
recently appeared at 7,200 feet in the Andes Mountains of Colombia.
Malaria has been detected in new higher-elevation areas in Indonesia.
WARMING WATER
Consequence: more powerful and dangerous hurricanes
Warmer water in the oceans pumps more energy into tropical storms, making
them more intense and potentially more destructive.
Warning signs today

The number of category 4 and 5 storms has greatly increased over the
past 35 years, along with ocean temperature.
Consequence: melting glaciers, early ice thaw
Rising global temperatures will speed the melting of glaciers and ice caps, and
cause early ice thaw on rivers and lakes.
Warning signs today

At the current rate of retreat, all of the glaciers in Glacier National Park will
be gone by 2070.

After existing for many millennia, the northern section of the Larsen B ice
shelf in Antarctica -- a section larger than the state of Rhode Island -collapsed between January and March 2002, disintegrating at a rate that
astonished scientists. Since 1995 the ice shelf's area has shrunk by 40
percent.

According to NASA, the polar ice cap is now melting at the alarming rate
of nine percent per decade. Arctic ice thickness has decreased 40 percent
since the 1960s.

In 82 years of record-keeping, four of the five earliest thaws on Alaska's
Tanana River were in the 1990s.
Adapted from http://www.nrdc.org/globalWarming/fcons.asp
Consequence: sea-level rise
Current rates of sea-level rise are expected to increase as a result both of
thermal expansion of the oceans and of partial melting of mountain glaciers
and the Antarctic and Greenland ice caps. Consequences include loss of
coastal wetlands and barrier islands, and a greater risk of flooding in coastal
communities. Low-lying areas, such as the coastal region along the Gulf of
Mexico and estuaries like the Chesapeake Bay, are especially vulnerable.
Warning signs today

The current pace of sea-level rise is three times the historical rate and
appears to be accelerating.

Global sea level has already risen by four to eight inches in the past
century. Scientists' best estimate is that sea level will rise by an additional
19 inches by 2100, and perhaps by as much as 37 inches.
ECOSYSTEM DISRUPTION
Consequence: ecosystem shifts and species die-off
The increase in global temperatures is expected to disrupt ecosystems and result
in loss of species diversity, as species that cannot adapt die off. The first
comprehensive assessment of the extinction risk from global warming found that
more than one million species could be committed to extinction by 2050 if global
warming pollution is not curtailed. Some ecosystems, including alpine meadows
in the Rocky Mountains, as well as tropical montane and mangrove forests, are
likely to disappear because new warmer local climates or coastal sea level rise
will not support them.
Warning signs today

A recent study published in the prestigious journal Nature found that at
least 279 species of plants and animals are already responding to global
warming. Species' geographic ranges have shifted toward the poles at an
average rate of 4 miles per decade and their spring events have shifted
earlier by an average of 2 days per decade.

In Washington's Olympic Mountains, sub-alpine forest has invaded higher
elevation alpine meadows. In Bermuda and other places, mangrove
forests are being lost.

In areas of California, shoreline sea life is shifting northward, probably in
response to warmer ocean and air temperatures.

Over the past 25 years, some penguin populations have shrunk by 33
percent in parts of Antarctica, due to declines in winter sea-ice habitat.
Adapted from http://www.nrdc.org/globalWarming/fcons.asp