Our planet is undergoing dramatic changes
right before our eyes. I am concerned about
the connection these changes have with
climate change, and I believe we can’t ignore
the evidence or climate change science any
longer.
Climate Change Science
The sun provides the solar radiation required
for Earth to maintain a stable, life-supporting
temperature. Solar radiation is cyclical; it
stops at night. Earth’s atmosphere contains
greenhouse gases (carbon dioxide, methane,
nitrous oxide and water vapor), which help
maintain the planet’s stable temperatures.
These greenhouse gases cloak Earth like a
blanket and allow shortwave radiation from
the sun to pass through the atmosphere and
warm the planet. They also absorb some of
Earth’s outgoing radiation and then reradiate
some of this absorbed energy — which would
otherwise be sent into outer space — back to
the Earth’s surface. Without the right mix of
greenhouse gases, Earth would be too cold to
support life.
Increased concentrations of greenhouse gases
are now causing the planet to get warmer. This
current warming is primarily the result of
human actions, especially the release of
carbon dioxide when humans burn carbon-
based fossil fuels (coal, oil and natural gas).
The extraction, processing and burning
of fossil fuels has created an atmospheric
overload of greenhouse gases.
Humans started using fossil fuels as an energy
source during the Industrial Revolution.
Before then, atmospheric levels of carbon
dioxide were about 285 parts per million
(ppm). In 2009, the level reached 390 ppm —
substantially higher than any time in the past
800,000 years. (See the climate change chart
in the Image Gallery.) Since 1850, Earth’s
surface temperature has risen 1.3 degrees
Fahrenheit, and the 20th century was warmer
than any time period in the past 400 years.
The Effects of Climate Change
Climate change is not just about rising
temperatures. It is also about other rapid
changes happening now. Unless we make
drastic adjustments, these changes will make
Earth a more hostile place to live. What follows
are the signs that climate change is already
affecting the planet we live on, and the
changes we can expect if global warming
continues unchecked.
Sea Level Rise
Rising sea levels are due to thermal expansion
of ocean water and melting of continental ice,
primarily in Greenland and western Antarctica.
The global rate of ice loss since 1990 is more
than double the rate of the previous 30 years.
In the past 3,000 years, mean sea level rose
0.4 to 0.8 inches. But due to global warming,
during the 20th century alone, mean sea level
rose 8 inches. On a beach with a gentle slope
of 1 degree, this 8-inch increase would move
the shoreline inland almost 40 feet, leaving
low-lying areas more vulnerable to floods and
hurricane damage.
If we continue our current rate of fossil fuel
use, scientists predict sea level will rise at least
3 feet by the end of the 21st century. Globally,
more than 100 million people live less than 3
feet above sea level. Coastal plains, such as
those along the Atlantic Ocean and the Gulf of
Mexico, are at the highest risk, along with the
major river deltas such as that of the
Mississippi River. Henry Pollack, a geophysicist
at the University of Michigan, points out that
if we don’t slow climate change now, climate
refugees will make our current immigration
complexities seem like a Sunday school picnic.
Arctic Ice Melt
Historically, floating summer ice in the Arctic
Ocean has covered an area about the size of
the United States. This ice reflects the sun’s
radiation and keeps the Arctic cool. But when
sea ice melts away, the dark sea absorbs the
sun’s radiation, which increases the water
temperature, triggers more melting and raises
the Arctic’s atmospheric temperature. Because
of this feedback loop, within only a few
decades, the Arctic Ocean could be ice-free in
the summer for the first time in 55 million
years.
Because of global warming and higher ocean
temperatures, scientists report that plumes of
methane (natural gas) are now rising from the
Arctic Ocean. As long as it remains cold and
under enough pressure, methane is stably
stored in the ocean floor, and some estimates
suggest there is more methane in the ocean
floor than in all of Earth’s fossil fuel
reservoirs. But signs that this methane is being
released hold serious implications for our
planet’s atmosphere, because methane is 20 to
25 times more potent than carbon dioxide as a
heat-trapping greenhouse gas.
Warm air rising from the Arctic Ocean to
arctic land masses triggers the melting of
permafrost, a concrete-like combination of
frozen water, soil and vegetation. Permafrost
extends over about 20 percent of the planet’s
land surface (mainly in the subarctic and arctic
regions of North America, Asia and Europe)
and can be up to 4,900 feet deep. When
permafrost melts, it also releases methane into
the atmosphere and causes land surfaces to
collapse — toppling buildings and buckling
roads. This melting also pushes more fresh
water into the ocean, decreasing the sea’s
salinity.
Mountain Glacier Melt
Mountain glaciers are rapidly disappearing,
straining supplies of glacial water needed for
agriculture, drinking water, sanitation and
hydropower generation. The meltwater from
the Himalayan and Tibetan Plateau glaciers, for
example, provide fresh water for the people of
India, China and most of Southeast Asia. One
of the principal glaciers feeding the Yangtze
River in China has retreated more than half a
mile in just over a decade.
In the northwestern United States, much of
the fresh water comes from the rapidly
disappearing glaciers of Mt. Rainier, the
Cascade Range and Glacier National Park.
Grinnell Glacier, in Glacier National Park, has
experienced a drastic, rapid recession. In
1850, Glacier National Park had 150 glaciers.
Today it has 25.
Forest Fires
As they grow, trees remove carbon dioxide
from the atmosphere through photosynthesis
and store an enormous amount of organic
carbon. Deforestation caused by forest fires
reduces photosynthetic activity — which
results in the atmosphere retaining higher
levels of carbon dioxide — and speeds the
release of the carbon stored in the trees into
the atmosphere as carbon dioxide.
Every degree increase in the temperature of
the western United States brings roughly a 6
percent increase in lightning strikes. In June
2008 alone, lightning strikes triggered 1,700
forest fires in California, resulting in millions
of burned acres.
Insect-Borne Diseases
In the past, deep winter freezes controlled the
populations of many destructive insects. Now,
winters are short and mild enough for the
larvae of the pine bark beetle, as one example,
to overwinter farther north. This beetle has
destroyed more than 35 million acres of forest
in British Columbia, Montana, Wyoming and
Colorado, has recently crossed the Continental
Divide into the forests of Alberta, and is
heading toward the Great Lakes, leaving behind
dead trees that fuel yet more forest fires.
Another example is the mosquito, which now
enjoys an extended geographic range thanks to
higher global temperatures. Mosquitoes harbor
disease-causing viruses such as dengue fever,
malaria and West Nile virus. Warmer weather
means more mosquitoes bite more people and
animals in more places around the globe,
resulting in more cases of these diseases. El
Salvador alone reported 22,000 cases of
dengue fever in 2008, 20 times the number in
2003.
Extreme Weather
In recent years, we have seen increased
numbers of hurricanes, more severe winter
weather, massive floods, heat waves and
droughts throughout the world. While weather
is not a direct indication of climate change,
the accumulating increase in severe weather
signals an overall climate shift that’s creating
powerful storms more frequently. (Read more
on how climate change relates to weather
events .) As sea levels rise and global
atmospheric temperatures rise, more
devastating weather events will occur —
especially in low-lying areas and riparian flood
plains — taking a greater financial and
emotional toll on society.
The Future
Everything in our lives is ultimately tied to
climate — where we live, water supply, food
production, health and even national security.
As changes begin, they trigger feedback loops
that advance climate change at faster and
faster rates. The Intergovernmental Panel on
Climate Change, the international research
authority on global warming, recently released
its Fourth Assessment Report, declaring that
the warming of Earth’s climate system is
“unequivocal.”
How are we going to incorporate the effects of
global warming into our lifestyle? How are we
going to prevent further changes from taking
place? We really have only two choices. We
can continue business as usual and hope for
the best, or we can end our current
dependence on nonrenewable fossil fuels and
move to a renewable energy economy with
solar panels, wind turbines and geothermal
systems. This will preserve the beautiful little
spot in the universe we call home.
The United States has about 4 percent of the
world’s population, but emits about 20 percent
of the world’s carbon dioxide. If the shift to a
renewable energy economy is to be successful,
the United States must be the leader. The time
to debate was yesterday. We must act today
