Is the impact of global warming restricted to changing sea levels and vegetation patterns?

Global Warming is principally the increase in the earth's temperature due to the use of fossil fuels and other industrial processes leading to a build-up of greenhouse gases (carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons) in the atmosphere. It has been known since 1896 that carbon dioxide helps stop the sun's infrared radiation from escaping into space and thus functions to maintain the earth's relatively warm temperature (greenhouse effect). There is however growing evidence that the increased levels of carbon dioxide in the atmosphere over the last century are leading to elevated global temperatures. Which could principally result in a sea level rise (through the melting of glaciers and polar ice caps) and changes to the world’s vegetation patterns (through climatic changes). This in turn relates to the essays main aim, by discussing the ‘view’ that global warming could be restricted by these immediate consequences.

One could say that the theories for changes in sea level and global vegetation patterns are more or less being proven conclusive in the form of physical evidence by means of photographs and scientific observations. Physical evidence if published in a scientific journal for example would convey the reality of global warming to the viewer, more or less proving that it was not just a scientific theory. This availability of hard evidence for the increasing global sea levels and changes in vegetation patterns would more or less ‘shun’ the rather weaker evidence for the other potential consequences, thus confirming that the impact of global warming was restricted. Scientists for example can now estimate the global rise in sea level between two years or even calculate the potential rise if a particular glacier melted. The 1995 estimate for instance tells us that sea level has risen between 1 - 2.5mm over the last 100 years. A major example of glacier melting can be well found in Europe, as many of it’s mountain glaciers have retreated during the last 100 years, this has often been related to the gradually increasing local air temperatures as indicated by the European climate records. A strong example of glacier retreat in Europe was when a five thousand-year-old body appeared on the Otztal Alps in September 1991. Subsequent work showed that he probably died in a snowstorm about 3200BC and was incorporated into a slowly moving glacier. If the weather had not warmed during the last century and the glacier had not begun to retreat the man would still be in his tomb. The finding of his body in a slow-moving glacier tends to indicate that the ice level in that valley is less than at any time since he died. A more conclusive example of sea level increase due to global warming would be the calving of large icebergs in Antarctica. In 1995 a giant iceberg was released from the Larson ice shelf in Antarctica which helped causes the break-up of both the Larson and Wordie ice shelves. This was in the peninsular area of Antarctica north of the main mass of ice where more than 3000 square miles of ice shelf have been lost in the last 50 years. Temperatures in the region have warmed more than 2.5 oC in the last 100 years. In just 50 days in 1995 500 square miles of the Larson ice shelf sent a plume of new icebergs into the Weddell Sea.

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Vegetation patterns like changes in sea level are better documented than most other potential affects due to their global impact, with the enormous potential consequences for the human race. Human activities have been proven to alter and diminish vegetation patterns, an example would be deforestation in hostile environments like in the Amazon rainforest and in arid parts of Africa like Nigeria where the potential for desertification is steadily increasing. The rate of desertification currently stands at about 60,000 square kilometres a year or 0.1 percent of the total dry land area. This knowledge of what can happen if we remove or alter vegetation patterns can lead many people to think of the potential consequences if global warming occurred. One might say that an alteration in vegetation patterns could directly cause other consequences like a reduction in agricultural activities. This would imply that global warming caused ‘chain-reaction’ consequences by the immediate consequences of global warming causing other sub-consequences to occur. If this notion were true it would confirm that the immediate impact of global warming was in a sense restricted by sea level rises and changing global vegetation patterns. Global warming could for example reduce rainfall in potentially arid areas where the existing vegetation was mainly shrub level growth (many parts of sub-Saharan Africa), if this died as a result of reduced rainfall then the stability of the soil would reduce due to the reduction in binding plant rootlets. The soil would then be more susceptible to wind erosion and leaching by rainwater, as transpiration would be reduced therefore reducing its fertility. Eventually making current or potential agricultural activity in this area extremely difficult as well as increasing the chance of desertification occurring. Forests and animal species will find it difficult to escape from or adjust to the effects of warming because humans occupy so much land. Under global warming vegetation will shift their ranges, seeking new areas, as old habitats grow too warm. In many places, however, human development will prevent this shift. Species that find cities or farmlands blocking there way north or south may die out. Many Boreal forests, unable to propagate toward the poles fast enough, may disappear. It is estimated that within the next 100 years many species would have to migrate between 100 and 340 miles in the direction of the poles. The upper end of this range is a distance typically covered by migrating forests in millennia, not in decades. Changing vegetation patterns could also cause some types of forest to displace each other, Boreal forests for example could be come displaced by temperate deciduous forests if the changed local climate favoured the growth of deciduous trees (increased local air temperature).

However much evidence points to the fact that global warming might not be restricted by global sea level rises and changes in vegetation patterns. Global warming for example could cause a spectrum of largely negative impacts on human health. The predicted decrease in the difference between day and night temperatures will result in more thermal extremes. Therefore, an increase in mortality from heat stress is likely, causing incidents like the 465 deaths in Chicago during the summer of 1995. As a result of warming, the area of the earth's surface experiencing severe frosts will probably decline. This will probably increase the geographical range of vector-borne diseases such as malaria, dengue, yellow fever, and encephalitis. Currently, 45 percent of the world's population is within the zone of potential malaria transmission. With predicted temperature increases, there will likely be an additional 50 to 80 million cases of malaria world-wide, bringing the percentage of the world's people within the susceptible zone to 60 percent. It is also likely that global warming will result in a decline in air quality due to increases in the abundance of air pollutants, pollen, and mould spores. This will probably cause an increase in the number of cases of respiratory diseases, asthma, and allergies. The change in the frequency and intensity of extreme weather events (floods and droughts) combined with warmer atmospheric temperatures, will probably result in a host of adverse health effects, among them, exposure to contaminated water supplies and death from diseases.

Global warming could destroy many coral atolls, as many of these islands are only a few metres above sea level. Thus, rises in sea level will not only cause a loss of land area, but an increase in periodic flooding. Freshwater resources of these islands will also be degraded through the salinisation of ground water. Such an effect can be seen in Micronesia as some of the smaller coral atolls of this country have been abandoned due to the rise in sea level. Furthermore, the country's main island, Nukuoro, was flooded with salt water, destroying their vital source of local food. Global warming could also cause coral bleaching as suggested by John Ogden (a leading coral expert) in 1991. He implied that nearly every reef system in the world was suffering from coral bleaching, along the coasts of more than 20 countries, including Australia, China, Japan, Thailand, Malaysia, the Philippines and India. Corals are inevitably one of the first organisms to show the consequences of a sustained increase in sea surface temperatures, as the increased sea temperatures cause the tiny algae (zooxanthellae) to expel from the coral reefs. Thus the coral loses its colour (causing it to turn a bleached white) and most of its food supply meaning it cannot grow. Coral reefs in Thailand are reported to be losing colour down to 8 metres due to the 2 degrees increase in the waters temperature, while 85 per cent bleaching has been reported in French Polynesian reefs. Global warming will probably change atmospheric temperatures and patterns of ocean circulation, vertical mixing and wave intensity. These changes will affect nutrient availability, biological productivity, and the structure and function of marine ecosystems. The melting of ice and snow in mountain glaciers and polar regions will also reduce the area of bright areas, which once reflected much of the Sun's light. As a result, there will be more “darker” surfaces on Earth to absorb the Sun's radiation, leading to an even warmer climate.

I therefore conclude that the impacts of global warming stray further a-field than sea level rises and changing vegetation patterns. This is proven by the evidence that backs up the potential for other impacts occurring, despite there being more evidence and logic for the potentially restrictive impacts. This view of global warming being restricted to two impacts is influenced by the fact that the media and most scientific journals refer to them more often. The melting of the ice caps is much more heard of when talking about global warming than the bleaching of corals for instance, thus influencing people’s perception of the potential impacts of global warming. The fact that the melting of the ice caps and changing of vegetation patterns might seem so catastrophic for the human race it can lead many people to ignore the other potential consequences. Which may have little impact for human civilisation but cause huge impacts for the globes bio-diversity and environment (non-human). One could also argue that the other impacts of global warming could be controlled by human intervention, as they are less global in terms of their impact. A greater vaccination rate or improved research into cures for diseases could for example control human health risks posed by global warming. While rising sea levels and changes to global vegetation patterns would be much more difficult to control. I firmly believe that the world’s climate is the key to the intensity and distribution of the impact of global warming. Climate influences all of the major impacts of global warming, it for example causes the air temperature rise in Antarctica so causing the edges of the ice sheet to retreat, it causes the increase in ocean temperatures causing the coral reefs to bleach. It can also cause a change in local climates thus affecting global vegetation patterns.

Bibliography:

BROWN,P.B (1996) Global warming can civilisation survive? London: Blandford
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS (1998)

Potential impacts of sea-level rise on populations and agriculture

<http://www.fao.org/waicent/faoinfo/sustdev/EIdirect/EIre0047.htm>

(updated on 22 March 1998, accessed on 2 January 2001)

MICROSOFT, Encarta Reference (2000) Global warming <http://encarta.msn.com/find/Concise.asp?z=1&pg=2&ti=761567022&cid=20#p20>

(updated 2000, accessed on 2 January 2001)

YALE-NEW HAVEN TEACHERS INSTITUTE (2000) Our mission: save planet earth. <http://www.yale.edu/ynhti/curriculum/units/1993/5/93.05.03.x.html#b>

(updated 2000, accessed on 16 December 2000).

Is the impact of global warming restricted to changing sea levels and vegetation patterns?

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Potential impacts of sea-level rise on populations and agriculture

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