Global Warming - Impacts and consequences of Global Warming

Content

1. Introduction and overview

2. Modelling the climate

3. Causes of Global Warming

4. Effects of global warming
4.1. Sea level rise
4.2 More extreme weather
4.3 Increased Evaporation
4.4 Ocean currents
4.5 Glacier Retreat

5. The Impacts of climate change
5.1 Economic Impacts
5.1.1 Agriculture and food supply
5.1.2 Cost of more extreme weather
5.1.3 Development
5.1.4 Migration
5.1.5 Other Sectors
5.2 Environmental Consequences
5.3 Health
5.4 Impacts of Glacier Retreat
5.5 Fresh Water Supply

6. Conclusion

Sources

1. Introduction and overview

Is Global Warming a reality? Will there be more serious disasters and will they be more frequent? And can human activities change the Earth´s climate system? These are questions that everyone is asking in these days.^[1] Global warming has become familiar to many people as one of the most important environmental issues of our day. Vice President Al Gore has divined that the threat of global warming, resulting from human production of greenhouse gases, is „the most serious problem our civilization faces.“ A series of studies on the impacts of climate change have systematically shown that the older literature overestimated climate damages by failing to allow for adaptation and for climate benefits.^[2] The scientific evidence is now overwhelming, that climate change presents very serious global risks, and it demands an urgent global response. It threatens the basic elements of life for people around the world. Access to water, food production, health, and use of land and the environment.^[3] Global warming is a reality. The global temperature has risen significantly over the last hundred years. In this past century, the temperature rise was faster and lasted longer than any period over the past ten thousend years.^[4] It is one of the most pressing environmental, social and economical problems facing the planet. Numerous studies have already reported changes in nature driven by global warming. The results of a recent study by American researchers suggests that, because of a rapid warming trend over the past decades, the Earth is now reaching, and exceeding, the warmest levels in the current interglacial period, which has lasted nearly 12,000 years.^[5] In figure 1 from the Intergovernmental Panel on Climate Change, you can see the global variations on the Earth´s surface temperature for the past 140 years, and for the past 1000 years in the Northern Hemisphere. On current trends, average global temperatures will rise by 2 - 3°C within the next fifty years or so.

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(Figure 1., IPCC)

The Earth will be committed to several degrees more warming if emissions continue to grow.^[6] This may not sound very much, especially when it is compared with normal temperature variations from day to night or between one day and the next. But you have to remember that it is not the temperature at one place but the temperature average over the whole world. Rising temperatures may sound appealing to people who live in cooler climates, but an increase in temperature will lead to global climate change.^[7]

2. Modelling the climate

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The first numerical model of the weather was set up by an English mathematician called Lewis Fry Richardson. Forty years later and based on Richardson´s methods, the first operational weather forecast was produced on an electronic computer Nowadays the computers are more than one million times faster that the one used for the first forecast. “Numerical models of the weather and the climate are based on the fundamental mathematical equations that describe the physics and dynamics of the movements and processes taking place in the atmosphere, the ocean, the ice and on land.”^[8] Weather forecast means forecasting of detailed weather over a few days and of average weather for a month or perhaps a season. Climate forecasts are concerned with longer periods of time, from a few years to a decade or longer. The Earth´s climate system is highly complex and a description of the climate over a period, is based on components of the weather over that period, together with the statistical

variations of those components. As you can see in Figure 2, climate cannot be described in terms of atmosphere alone. There are five components that make up the climate system. The atmosphere is coupled to the ocean, the land, ice and the biosphere.^[9]

3. Causes of Global Warming

Scientists believe that the observed global warming is mainly due to changes in human activities and related increases in greenhouse gas emissions. These changes are driven by worldwide population and economic growth, and the production and consumption of fossil fuels, as well as the intensification of agricultural activity and land use changes.^[10] The so-called greenhouse gases absorb the long-wavelength infrared radiation from the earth´s surface and atmosphere, trapping heat that would otherwise radiate into space. This effect has been beneficial to us in the past because without this capacity to conserve heat, the temperature on Earth would be below the freezing point and making life impossible. The problem about the greenhouse effect is, that since the Industrial Revolution and especially in the second half of our century, human industrial activity has constantly increased the amount of greenhouse gases in the atmosphere, leading to more heat being conserved and therefor warming up our planet. The mix and distribution of these gases influences the climate on a planet.^[11] There is an entire suite of greenhouse gases that have been increasing in modern times as a result of human activities. The most important are carbon dioxide (CO2), methane(CH4), and nitrous oxide (N2O) account for the majority of human induced global warming effects. Other gases are hydrofluorocarbons (HFCs), perluorocarbons (PCFs) and sulphur hexafluoride (SF6). Largest constributor, as a single nation, are the U.S. for whereas only 5% of the world population live in the U.S., 21% of greenhouse gases are emitted here.^[12] CO2 contributes 60% of the greenhouse effect and it enters the atmosphere through the burning of fossil fuels, solid waste and wood. It is also removed from the atmosphere when it is absorbed by plants as part of the biological carbon cycle. “Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from livestock and other agricultural practices and by the decay of organic waste in municipal solid waste landfills.” Agricultural and industrial activities are also responsible for nitrous oxide. Fluorinated gases like hydrofluorocarbons and perluorocarbons are synthetic this means that they are created and emitted solely through human activities.^[13]

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(Figure 3., IPCC)

As you can see in Figure 3 the emission of greenhouse gases increased since the industrial area. But while each of them acts to warm the surface of the Earth, the long-term climatic effects of the other greenhouse gases differ from those of CO2. Methane, for example, has an atmospheric lifetime of only about twelve years. Thus, most of the CH4 that our activities add to the air this year, in 2007, will be gone by 2019. By comparison, newly added CO2 will remain from decades to thousands of years. As a result, about 65 percent of the carbon dioxide that human activities have generated since the start of the Industrial Revolution in the early 1700s is in the air we breathe today, as is some that arose from the campfires of Attila the Hun, more than a thousand years before.^[14] Fossil fuel combustion is very important for producing energy and it is pretty much at the heart of our modern standard of living. The agricultural revolution which supports a human population of 6 billion people and more, depends on the production of fertilizers which is a very energy intensive process. This means that it is not easy to stop CO2 emissions because the countries and companies have a strong interest in continuing to do so.^[15]

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^[1] c.v. Houghton J., Global Warming 2004, p.1-2

^[2] c.v. Moore T., Climate of Fear 1998

^[3] c.v. www.co2-handel.de, Stern Report, p. 1

^[4] c.v. OECD, Environmental Outlook 2001, p.157

^[5] c.v. www.umg-verlag.de, 12.10.2006

^[6] c.v. www.co2-handel.de, Stern Report, p.6

^[7] c.v Houghton J., Global Warming 2004, p. 8-10

^[8] c.v. Houghton J., Global Warming 2004, p.77-78

^[9] c.v. Houghton J., Global Warming 2004, p.88-90

^[10] c.v. OECD, Environmental Outlook 2001, p.157

^[11] c.v. Tietenberg T., Environmental and Natural Resource Economics 2003, p. 404

^[12] c.v. www.gcrio.org.

^[13] c.v. www.epa.gov/climate change

^[14] c.v. www.gcrio.org

^[15] c.v. Archer D., Understanding the forecast, p. 4