Signs of Global Warming

Rising global temperatures have already had a major impact on the environment and ecosystems in many regions of the world. The 2007 IPCC report, for example, found that numerous environmental changes can be clearly linked to climate change. Arctic glaciers are rapidly melting, creating more and larger glacial lakes and increased earlier spring runoff into snow-fed rivers. Mountainous regions are experiencing more rock avalanches. And warmer temperatures are causing previously frozen soil, called permafrost, to thaw, causing increasing ground instability in northern latitudes.

The IPCC report also says warming water temperatures are causing changes in some Arctic and Antarctic ecosystems. Changes in ice cover, water salinity and acidity, oxygen levels, and water circulation, for example, are harming algae, fish, and plankton (microscopic marine life that provide food for many larger marine creatures). And rising sea levels are causing losses of coastal

wetlands and mangrove forests, which in turn contribute to more coastal flooding. Other changes are occurring in land-based biological systems. Events such as the unfolding of leaves, laying of eggs, and migration, which usually happen in the spring, are now happening earlier, and many plants and animals are moving northward and to higher altitudes as temperatures warm. Many experts believe that larger Arctic creatures, such as polar bears and the seals they feed on, are starving and well on their way to extinction.

So far, the state of Alaska is the region in the United States most affected by global warming. Reporter Timothy Egan provides the distressing details of these changes:

In Shishmaref [Alaska], on the Chukchi Sea just south of the Arctic Circle, it means high water eating away so many houses and buildings that people . . . [may] move the entire village inland. In Barrow, the northernmost city in North America, it means coping with mosquitoes in a place where they once were nonexistent, and rescuing

This chart shows ecosystems that are being threatened by global warming.

World's natural treasures at stake

Many sensitive ecosystems around the world are suffering irreversible damage from rising global temperatures.

Regions at risk from global warming

rain forest East Africa Reef, Australia
The Portage Glacier in Alaska can no longer be seen from the visitors center, which was built in 1986. Many people feel the retreat of the glacier is due to global warming. Alaska is the state that has been most affected by global warming.

hunters trapped on breakaway ice at a time of year when such things once were unheard of. In Fairbanks, where wildfires have been burning . . ., it means living with hydraulic jacks to keep houses from slouching on foundations that used to be frozen all year. Permafrost, they say, no longer is permanent. On the Kenai Peninsula, a recreation wonderland south of Anchorage, it means living in a 4 million-acre spruce forest that has been killed by beetles, the largest loss of trees to insects ever recorded in North America, federal officials say. Government scientists tied the event to rising temperatures, which allow the beetles to reproduce at twice their normal rate.22

2007 Drought Oscarville
In 2007 one of the worst droughts in Georgia's recent history saw water levels recede to record levels, as is shown here at Lake Lanier, where dry land is exposed where water once covered the shoreline.

Human health, too, is already being affected by global warming. In Europe, for example, heat waves have led to a rise in heat-related deaths in recent years. Extreme temperatures in the summer of 2003, for example, are believed to have caused thirty-five thousand deaths in European Union countries. In fact, climate researchers say that since 1880, extremely hot days have become almost three times more frequent in the region, and the length of these heat waves has doubled. Other parts of the world are noticing different health threats as a result of rising temperatures. In 2007, countries in Southeast Asia, such as Vietnam, Indonesia, Thailand, and Cambodia, experienced one of the worst-ever outbreaks of dengue fever, a serious illness carried by mosquitoes that causes fever, joint pain, and sometimes death. Dr. Thawat Suntrajarn, director of Thailand's Department of Communicable Diseases, explained, "Experts say it's partly due to global warm-

ing because it's increased the amount of water, not only sea water, but fresh water where mosquitoes breed."23

Moreover, periods of severe weather—both heavy precipitation and sustained droughts—have become more common, and this has caused a decline in food production in some parts of the world. One of the areas most affected is the continent of Africa, which in recent years has been experiencing both torrential floods and severe drought—each a threat to the region's food supply. In 2002-2003, for example, southern Africa suffered from a drought that caused a serious food deficit in which an estimated 14.4 million people needed food assistance, and in 2007, West Africa was hit with heavy rains and widespread flooding that also destroyed crops. In 2007, Australia, too, faced an unprecedented drought that led to severe water restrictions, crop failures, and a drying up of rivers in the Murray-Darling river system—the source of irrigation for much of the country's food production.

Continue reading here: Positive Effects on Agriculture

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