Climate Change
Introduction
The Earth's climate system is shaped by the winds and currents that move heat and moisture around the planet to cycle the atmosphere and the oceans. As such, global climate change is affected by a myriad of factors, ranging from solar wind from the sun to greenhouse gases on the Earth. Scientists understand that the Earth's climate has always changed over history, but it is the current rate of change that has suddenly become an alarming reality.5
The Observed Facts
Over the past century, dramatic increases have been observed in terms of sea-levels, which are largely governed by the extent of polar ice caps, and surface air temperature.
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The Debate: Are Human Activities Affecting the Climate?
The international community has intensely debated the extent to which human activities have affected the global climate system, but no clear answer has emerged. There are generally two opposing schools of thought, and both have significant scientific research and evidence to support their arguments.
First, the vast majority of climate scientists charge that human activities, particularly in terms of the consumption of fossil fuels and the release of greenhouse gases into the atmosphere, are affecting and increasing the extent of the greenhouse effect. The overall result is that the planet should be getting warmer, especially since the dawn of the industrial revolution, a prediction that coincides with current observations.8
While the United Nations may subscribe to the first school of thought and bring about the creation of treaties such as the Kyoto Protocol to control emissions, there are a significant number of scientists and experts who oppose this viewpoint. They cite research that shows that the Earth's temperature and climate has varied - sometimes quite rapidly - over the course of time due to natural causes. Such factors include the sun, volcanic activity, and weather patterns such as El Nino and La Nina. They claim that human activities could not possibly match the scale of the climate variations imposed by these natural factors: climate change is ultimately an aspect of life on Earth that we cannot control.9
For whatever reasons climate change is taking place, the observed fact remains that it is taking place right now and it has real consequences.
The Greenhouse Effect
Before examining the causes of climate change in more detail, it is important to understand how some of the climate systems that affect life on the Earth work.
The greenhouse effect is what makes life as we know it possible on the Earth. As the sun's energy reaches the Earth, it passes through the atmosphere. Some of the energy is absorbed by the ground, but most of it is reflected back up. In turn, some of this reflected energy is absorbed by particles in the atmosphere known as greenhouse gases. These gases effectively form a protective blanket around the Earth to protect it from the cold temperatures of space and to warm the surface of the planet. If the concentration of greenhouse gases were increased, the strength of the greenhouse effect would increase and the temperature on the surface of the planet would be higher.10
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Without Greenhouse Effect
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With Greenhouse Effect
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Equally important to regulating the Earth's temperature is the carbon cycle, which governs how greenhouse gases in the atmosphere interact with forests, plants, and the oceans. Changes in the concentration of carbon at one level ultimately affects all other aspects of the cycle.12
Sources / Causes of Climate Change
Because of the dynamic nature and complexity of the Earth's climate system, many different sources and causes of climate change have been identified.
The sun's cycles and solar wind
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The sun, which ultimately regulates all aspects of life on the planet, goes through periods of increased and decreased solar activity, which in turn affect how much energy the Earth receives. These cycles can vary in length from as little as ten years to many millions of years.14
Some scientists suggest that recent changes in the amount of solar wind, which is made of small electrically charged particles from the sun, has affected the extent of cloud cover on the Earth, resulting in an increase in global temperatures.15
Greenhouse gases
The extent of the greenhouse effect is directly related to the concentration of greenhouse gases in the atmosphere. As the concentration increases, the insulating ability of the atmosphere increases, and the temperature on the surface of the Earth rises.
The single most important greenhouse gas is water vapour (H2O), which occurs naturally in the atmosphere in the form of clouds which cover most of the Earth. The clouds absorb sunlight and reflect energy back towards the Earth, increasing the surface temperature. The amount of water vapour in the atmosphere is regulated by the water cycle and is generally not affected by human activities, but does vary in combination with other factors such as solar wind and land use.
Since the dawn of the industrial revolution, the combustion of fossil fuels - oil, gas, and coal - has provided the energy to create the lifestyle we enjoy on Earth today. While they represent an immensely useful energy source, the combustion of these substances releases greenhouse gases into the atmosphere.16
The most important greenhouse gas released by human activities is carbon dioxide (CO2), with methane (CH4), nitrous oxide (NO2), and chlorofluorocarbons (CFCs) all playing an important role as well. The table below summarizes what human activities lead to the release of each of these gases:17
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Greenhouse Gas
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Human Activities
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Carbon Dioxide (CO2)
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Released during the burning of fossil fuels (industry, automobiles, etc.), wood and wood products, and solid waste.
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Methane (CH4)
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Emitted during the extraction and production of fossil fuels, the decomposition of organic wastes from herding and farming, and the decomposition of municipal landfills.
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Nitrous Oxide (NO2)
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Emitted during agricultural and industrial activities, as well as during the combustion of fossil fuels and solid waste.
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Chlorofluorocarbons (CFCs)
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Released during the production of foams and as a by- product from refrigeration and air-conditioning appliances.
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The volume of these gases entering the atmosphere due to human activities has been increasing steadily over the course of history to unprecedented levels and is believed to be warming the planet by increasing the magnitude of the greenhouse effect.18
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Land Use
It has been suggested that the way humans alter the landscape of the Earth plays just as an important role in affecting the climate as greenhouse gases. The increase in greenhouse gas emissions coincides with an equally large expansion of urban sprawl, agricultural land, and deforestation. All of these factors, especially the deforestation of tropical rainforests, remove plants and vegetation that absorb carbon dioxide from the atmosphere.
The advent of municipal landfills, which openly vent methane into the air, has increased concentration of greenhouse gases in the atmosphere. Asphalt and buildings in urban centers absorb energy much more readily than the surrounding countryside, resulting in higher temperatures in cities and built up areas. Agricultural irrigation and the clearing of forested areas for farmland change the rainfall patterns, humidity, and cloud cover of the land, all of which can combine to drastically change the climate of a region.20
Implications of a Global Temperature Rise
With the combined power of all of its various sources, climate change poses a real and significant threat to the general well-being of life on the planet. A global increase in temperature has many major implications:
Droughts
An increase in temperature results in drier conditions in some areas, many of which are important agricultural lands, as rainfall patterns change.
At its most basic level, droughts mean lower crop yields from farming, which negatively affects the economy and food supply. Lower yields cause an increased demand for irrigation, which, coupled with the already dry conditions, threatens the quantity and quality of the available water supply.
Drier conditions also increase the risk of forest fires, which damage ecosystems and release more greenhouse gases into the air.21
Heat Waves and Human Health
Longer and more intense summer heat waves would make air pollution in large urban areas worse. Air pollution has been linked to increased deaths and illnesses from respiratory diseases such as asthma.
Increased use and stress on air conditioning and other cooling mechanisms during heat waves causes an increased consumption of energy and a greater release of CFCs into the atmosphere.
Hotter conditions also facilitate the spread of infectious tropical diseases northward and increase the extent of swarming insects, both of which threaten lives and well-being.22
Rising Sea Levels
A global increase in temperature causes polar ice caps and glaciers to melt, raising sea levels.
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Sea-level rises would increase erosion and flooding along coastlines, threatening many cities. Based on current projections, it has been suggested that the New York City subway system would be flooded by 2050, and most of the city's harbour would be unusable due to the higher sea levels.24
Many low-lying regions of the world; such as much of the state of Florida or countries like Singapore, the Maldives, and Nauru; are in danger of completely disappearing beneath the waves if sea levels rise extensively. Such regions have recently formed a panel to raise awareness about climate change and the severity of their situation.25
Severe Weather
The overall amount of energy in the Earth's climate system increases with temperature, which ultimately means there will be more severe weather events.
More violent thunderstorms, heavy rains, hurricanes, cyclones, hail, and tornadoes could take a serious toll on both lives and property, particularly through flooding in developing nations. Coupled with already rising sea levels, the damage to coastal infrastructure would be serious.
It is for this reason that many insurance companies are strong supporters of action programs to help reduce climate change. The costs, both in terms of losses due to damages and replacement, would be extensive and would weaken businesses and economies worldwide.26
Concluding Remarks
The controversy surrounding the science of climate change is increased by the fact that there are no two computer models for future temperatures that are contiguous and completely accurate. It has been strongly argued by advocates that, given the cumulative nature of the climate process, the world cannot use a "wait and see" approach when deciding how to address this issue. The scientific community has succeeded in raising the alarm such that the governments of countries from around the world have started working together towards agreements to help control climate change. One such agreement is the Kyoto Protocol, which has a history of being a controversial issue in itself.
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