Minggu, 02 Desember 2007

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"

Scientists say that the earth could warm by an additional 7.2 degrees Fahrenheit during the 21st century if we fail to reduce emissions from burning fossil fuels, such as coal and oil. This rise in average temperature will have 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.

Consequence: warmer temperatures
Average temperatures will rise, as will the frequency of heat waves.

Fact :

  • Most of the United States has already warmed, in some areas by as much as 4 degrees Fahrenheit. In fact, all states experienced either "above normal" or "much above normal" average temperatures in 2006.

  • The National Oceanic and Atmospheric Administration (NOAA) declared 2006 to be the second warmest year on record for the United States, with an annual average temperature of 55 degrees Fahrenheit -- within 0.1 degrees of the record set in 1998.

  • Every year from 1998 through 2006 ranks among the top 25 warmest years on record for the United States, an unprecedented occurrence, according to NOAA

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.

Fact :
  • In 2003, extreme heat waves claimed an estimated 35,000 lives in Europe. In France alone, nearly 15,000 people died due to soaring temperatures, which reached as high as 104 degrees Fahrenheit and remained extreme for two weeks.

  • Much of North America experienced a severe heat wave in July 2006, which contributed to the deaths of at least 225 people.

  • Studies have found that a higher level of carbon dioxide spurs an increase in the growth of weeds whose pollen triggers allergies and exacerbates asthma.

  • 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.
Consequence: melting glaciers, early ice thaw, sea-level rise
Rising global temperatures will speed the melting of glaciers and ice caps, and cause early ice thaw on rivers and lakes. Current rates of sea-level rise are expected to increase as a result both of thermal expansion of the oceans and melting of most mountain glaciers and partial melting of the West 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.

Fact :
  • Global sea level has already risen by four to eight inches in the past century, and the pace of sea level rise appears to be accelerating. The IPCC predicts that sea levels could rise 10 to 23 inches by 2100, but in recent years sea levels have been rising faster than the upper end of the range predicted by the IPCC.

  • In the 1990s, the Greenland ice mass remained stable, but the ice sheet has increasingly declined in recent years. This melting currently contributes an estimated one-hundredth of an inch per year to global sea level rise.

  • Greenland holds 10 percent of the total global ice mass; if it melts, sea levels could increase by up to 21 feet.
  • 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.

  • Arctic sea ice extent set an all-time record low in September 2007, with almost half a million square miles less ice than the previous record set in September 2005, according to the National Snow and Ice Data Center. Over the past 3 decades, more than a million square miles of perennial sea ice -- an area the size of Norway, Denmark and Sweden combined --has disappeared.
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.

Fact :
  • A recent study of nearly 2,000 species of plants and animals discovered movement toward the poles at an average rate of 3.8 miles per decade. Similarly, the study found species in alpine areas to be moving vertically at a rate of 20 feet per decade in the 2nd half of the 20th century.

  • The latest IPCC report found that approximately 20 to 30 percent of plant and animal species assessed so far are likely to be at increased risk of extinction if global average temperature increases by more than 2.7 to 4.5 degrees Fahrenheit.

  • Some polar bears are drowning because they have to swim longer distances to reach ice floes. The U. S. Geological Survey has predicted that two-thirds of the world's polar bear sub-populations will be extinct by mid-century due to melting of the Arctic ice cap.

  • 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.

  • The ocean will continue to become more acidic due to carbon dioxide emissions. Because of this acidification, species with hard calcium carbonate shells are vulnerable, as are coral reefs, which are vital to ocean ecosystems. Scientists predict that a 3.6 degree Fahrenheit increase in temperature would wipe out 97 percent of the world's coral reefs.

0 komentar: