Impacts Of Global Warming

According to a report in the New York Times in January 2008, an article appearing in the journal Nature Geoscience reported that warming water temperatures and wind patterns consistent with global warming have been discovered to be eroding the ice sheets of Antarctica faster than anyone had previously thought. Up until recently, Antarctica has been one of the "inconsistencies" that opponents of global warming have used to make a case against it—saying that because notable melting is not occurring there, global warming is not a serious issue. This is no longer the case. Although the loss is not massive at this point, the study does suggest that if the trend continues, it could cause global sea levels to rise much more rapidly than originally predicted by climate-change scientists. To the proponents of global warming, this adds an increased urgency to cut back the emissions of CO2 and other greenhouse gases— many of which have an even greater global warming potential (GWP).

In particular, West Antarctica's huge ice shelf (which is roughly the size of Texas) is losing ice 60 percent faster today than it was just 10 years ago. Based on this information, the IPCC warns that if nothing is done to decrease greenhouse gas emissions, the world's oceans could rise more than 2 feet (0.6 m) by 2100.

Another impact of global warming that has not had much exposure in past news, but is quickly coming to the forefront, is a disaster facing the polar regions. According to a report in LiveScience, a phenomenon that could "damage structures in northern areas, reconfigure towering mountains, and alter biology" has become a pressing issue.

As northern, high-latitude winters continue to become increasingly milder, dangerous changes are occurring. Although not visible at first, the process can occur over a period of time before its effects manifest themselves: the melting of the permafrost layer. Nearly one-fourth of the land in the Northern Hemisphere has a layer of permafrost beneath it—a layer of perennially (occurring all year) frozen ground.

Global warming is changing this balance, however. The areas that are frozen seasonally have decreased by 15 to 20 percent during the past century. According to Tingjun Zhang of the University of Colorado at Boulder, "In the last 20 years, the decrease is more dramatic. The change is real. It's happening."

Regions in Russia have been documented where 16 inches (40 cm) below the surface have warmed 1°F (0.6 °C) in average soil temperature. In the extreme northern areas of permafrost where it is melting, it is realigning roads, railroad tracks, toppling houses, cracking founda-

The Trans-Alaska pipeline extends 800 miles (1,287.5 km)—posts are designed to keep permafrost frozen so as to support the pipeline. Topped with fanlike aluminum radiators, the posts absorb cold from the winter air. When the air temperature is, for example, 40 below, the posts take on the same temperature, making the soil around them 40 below too, which keeps the permafrost from melting. The pipeline was built in a zigzag pattern to allow the pipe to expand and contract. (Patrick J. Endres,

tions, causing landslides and mudflows, breaking pipelines, and damaging other infrastructure.

The effects are not just confined to the polar regions, either. In the United States, 80 percent of its soil freezes every year. Changes to this cycle will have detrimental effects such as damage to agricultural lands, native plants, and carbon exchange mechanisms between vegetation and the atmosphere.

Frederick Nelson, a geographer at the University of Delaware, says, "There is widespread evidence that global warming is responsible for the observed changes in seasonally frozen soil and permafrost. Thawing permafrost will profoundly affect biological activity in ways that are not fully known."

When the freezing period does not last as long, making the soil thaw earlier because of global warming, deeper zones in the permafrost region of the soil end up thawing as well. Each year of mild winters, the zone of thawing reaches deeper and deeper, destroying the permafrost. This makes the ground swell and expand when it freezes and contract and shrink when it melts, causing uneven movements on the ground's surface. Over time, this expanding/contracting cycle causes structural damage in urban areas to railroads, roads, and buildings. In natural areas, it can cause landslides and mudslides.

This situation has been addressed by the Qinghai-Xizang railroad in Tibet. The railroad is 695 miles (1,118 km) long, and half of it is built above 13,000 feet (3,962 m). Half of its length is located on zones of permafrost, and according to Tingjun Zhang, this will melt in the coming years because of global warming. Because of this, the railroad stands on a unique insulation system—it rests on a thick layer of crushed rock that covers the permafrost zone.

Charles Harris at Cardiff University in the United Kingdom has documented rockslides at high elevations in the Swiss Alps, which were related to thawing permafrost zones. In fact, in 2008—the warmest summer recorded in the Alps—the slushy "active" layer of permafrost shifted from its long-term 15 feet (4.5 m) to 29 feet (9 m) below the surface of the ground.

According to Harris, "There is likely to be an increase in rock falls and landslides at high altitude sites."

The latest report issued by the IPCC in 2007 outlines the impacts that will require mitigation and adaptation as follows: Global effects as of 2007:

• enlargement and increased numbers of glacial lakes;

• increasing ground instability in permafrost regions;

• increasing rock avalanches in mountain regions;

• changes in Arctic and Antarctic ecosystems, particularly with polar bears;

• increased runoff and earlier spring peak discharge in many glacier- and snow-fed rivers;

• warming of many lakes and rivers;

• earlier timing of spring events such as leaf unfolding, bird migration, and egg-laying;

• poleward and upward shifts in ranges in plant and animal species;

• shifts and changes in algal, plankton, and fish abundance in high-latitude oceans;

• increases in algal and zooplankton abundance in high-latitude and high-altitude lakes;

• range changes and earlier migrations of fish in rivers;

• increase in ocean acidity.

Regional climate changes as of 2007:

• effects on agricultural and forestry management at Northern Hemisphere higher latitudes, such as earlier spring planting of crops and changes in forest ecosystems due to fires and pests (insects);

• human health issues such as heat-related mortality, infectious diseases, and allergenic pollen;

• disturbance of human activities in the Arctic (transportation, hunting, travel over snow and ice);

• drought in areas such as the Sahelian region of Africa;

• flooding along coastal wetlands and shorelines.

Fortunately, much work has been done worldwide and sufficient progress has been made in understanding the types of impacts humans are now, and will be, facing due to the effects of global warming. Having a solid understanding of the impacts allows action to be taken in the form of mitigation.

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