Since the 1980s, global warming has been a hotly debated topic in the popular media and among the general public, scientists, and politicians. The debate is about whether global warming has been occurring, whether it is an issue with which the global community needs to be concerned, and whether the current global warming is part of natural cycles of warming and cooling. Currently, the nature of the debate has begun to focus on whether there is anything we can do about global warming. For some, the problem is so insurmountable, and there seems to be so little we can do, that it is easier to entirely forget there is a problem.
In order to understand the changes that need to be made to have any meaningful and lasting impact on the level of global warming, the science behind the greenhouse effect must be understood.
The Scope and Nature of Global Warming
The average temperature on Earth is approximately 15 degrees Celsius. The surface of the Earth stays at such a consistent temperature because its atmosphere is composed of gases that allow for the retention of some of the radiant energy from the sun, as well as the escape of some of that energy. The majority of this energy, in the form of heat, is allowed to leave the atmosphere, essentially because the concentrations of gases that trap it are relatively low. When solar radiation escapes the atmosphere, it is largely due to the reflection of that energy from clouds, snow, ice, and water on the surface of the Earth. The gases that trap heat are carbon dioxide, methane, nitrous oxides, and chlorofluorocarbons. These gases are commonly known as greenhouse gases.
In the last 60 years, the percentage of greenhouse gases (in particular, carbon dioxide) has begun to climb. Although the global increase in these gases has been noticed since the beginning of the Industrial Revolution approximately 200 years ago, the increase since the 1950s has been much more dramatic. Carbon dioxide comes from such sources as plant and animal respiration and decomposition, natural fires, and volcanoes. These natural sources of carbon dioxide replace atmospheric carbon dioxide at the same rate it is removed by photosynthesis. Human activities, however, such as the burning of fossil fuels, pollution, and deforestation, add excess amounts of this gas and therefore disrupt the natural cycle of carbon dioxide.
Scientists have discovered this increase in carbon dioxide and other greenhouse gases by drilling into ice caps at both the north and south poles and in glaciers and by taking ice-core samples that can then be tested. Ice cores have rings, similar to the rings found in trees, which allow for accurate dating. When snow and water accumulate each season to form the ice in these locations, air bubbles are trapped that are now tested for the presence of greenhouse gases. These studies have shown drastic changes in the levels of carbon dioxide.
Global warming is significantly affected by the burning of fossil fuels and the massive loss of vegetation. First, the loss of vegetation removes photosynthetic plants that consume carbon dioxide as part of their life cycle, and second, the burning of fossil fuels releases carbon dioxide that has been stored for thousands of years in decayed plant and animal material into the atmosphere. These two processes have increased significantly globally in the last 100 years.
Although the rate of warming seems small and gradual, it takes only minor temperature fluctuations to have a significant effect on the global scale. During the last ice age, temperatures were less than 5 degrees Celsius cooler than they are today. This small change in temperature is so significant because of the properties of water. Water has a high specific heat, meaning it takes a large amount of heat energy to warm water. The result of this is that it takes a long time to warm or cool large bodies of water. This effect can be noticed in the temperate climate experienced in coastal areas. Once the oceans begin to warm, they will stay warm for an extended period of time. This is critical for life that has adapted to the temperatures currently experienced in the oceans.
The other important and alarming factor related to global warming and the warming of the oceans is the loss of the ice caps at both poles. This melting of ice has the potential to raise the level of the oceans worldwide, which will have potentially disastrous effects for human populations. The largest urban centers worldwide are located in coastal areas, which have the potential to flood. This will displace millions, and possibly billions, of people.
These changes are only gradual when considered within a human time frame. In terms of geological time, the change is extremely fast. This precipitous change will have far-reaching effects on both flora and fauna because most species will not have time to adapt to changes in climate and weather patterns.
The result of this will be extinctions of species on a scale that is difficult to predict. It is certain that changes that have already taken place have had an impact on polar species, such as polar bears, because that habitat is where the changes are most strongly felt right now.
Global Warming and Socioeconomic Disparities
One of the largest issues in the debate on global warming is the difference in the ability to deal with mitigation and the large disparity in the consequences felt between developing and developed nations. The reality faced by many developing nations of poverty and subsistence living means that those populations do not have the ability to withstand some of the changes with which the world is faced. The most vulnerable people living in developed countries will not be able to adapt as easily.
These people, who generally do not contribute as much to the problems associated with an increase in greenhouse gases, will suffer the consequences most severely. Their contributions to global warming are less because many in this segment of the global population do not own cars, do not have electricity or refrigerators with chlorofluorocarbons, do not use air conditioning, and so on. Their lives are generally more closely tied with climate than those more fortunate, however. Their work may involve physical labor outside, they usually are involved in agriculture, or they may not be able to access health care for the inevitable increase in climate-related diseases such as malaria. The large and growing populations of many developing nations live mainly in coastal areas; less privileged people will not have the resources needed to move away from rising water levels. This means there will be a large refugee population that the international community will not easily be able to help.
Rapidly developing nations such as China and India, playing catch-up with the West, are becoming, if they are not already, major contributors to global warming. Older technologies, outdated equipment, and the nature of developing an industrial sector are largely to blame. In the development stage of industry, high carbon dioxide–emitting sectors such as shipping and manufacturing are predominant. Worldwide, work is needed to assist nations in developing their economies without sacrificing the environment to do so.
Global warming is not merely an issue of science and environmental protection; it is also a humanitarian and ethical concern. The methods of mitigation are being debated, and there is no clear answer to the questions concerning the appropriate measures to take. There are generally two appropriate responses. The first is to take any and all steps to immediately reduce the amount of pollution and greenhouse gas emission worldwide, or there will be no life on Earth. The second approach is based on the thought that nothing we do will have a lasting effect on the amount of pollution, so we must better equip the people of the world to deal with the consequences of this crisis. This means breaking the poverty cycle, addressing such issues as disease and access to good food and water, and providing appropriate education on a global scale.
Another debate surrounding mitigation of global warming is whether individual effort will have an effect on rates of carbon dioxide and other greenhouse gases. Will one person choosing to ride his or her bike or take public transit reduce the level of emissions across the globe? If one person uses electricity generated by wind instead of coal, is that enough? Critics say that public apathy is so high, and there is such a strong sense of entitlement to resources, that there will never be enough people making the so-called green choice to make any kind of a difference at all. Others feel that all change must happen at a grassroots level and that every step counts and is important. If every single person in North America cut by half the number of hours they spent driving, there would of course be a significant decrease in pollution.
Rising global temperatures are expected to raise the sea level and alter the climate. Changing regional climates alter forests, crop yields, and water supplies. The most recent reports from the United Nations Food and Agriculture Organization indicate that wheat harvests are declining because of global warming. Some experts have estimated that there will be a 3 to 16 percent decline in worldwide agricultural productivity by 2080. Population is expected to rise, however.
The political controversies around global warming focus on the results of climate changes. Equity, value clashes, and uncertainty all promise to make climate change controversial. Some may gain and others will lose. There may be geopolitical shifts in world power. All efforts toward sustainability will be affected by global warming. Closer attention to environmental conditions of the climate, earth, land, air, and water is required to accommodate increasing population growth and concomitant environmental impacts. International treaties, such as Kyoto and the recent Copenhagen Summit, will be pointed to in seeking accords. Both the effects and causes of global warming promise to be a continuing controversy.
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