Global Warming Essay

Global Warming Essay

1.1 What is Global warming?

What is global warming? Global warming is an increase in the Earth’s average atmospheric temperature that causes corresponding changes in climate. This results from an increase greenhouse effect.

A panel convened by the U.S National Research Council, (the USA’s premier science policy body), in June 2006 voiced a “high level of confidence” that Earth is the hottest it has been in at least 400 years, and possibly even the last 2,000 years. Studies indicate that the average global surface temperature has increased by approximately 0.5-1.0�F (0.3-0.6�C) over the last century. This is the largest increase in surface temperature in the last 1,000 years and scientists are predicting an even greater increase over this century. This warming is largely attributed to the increase of greenhouse gases (primarily carbon dioxide and methane) in the Earth’s upper atmosphere caused by human burning of fossil fuels, industrial, farming, and deforestation activities including.

1.2 Green house effect

There are two meanings of the term “greenhouse effect”. There is a “natural” greenhouse effect that keeps the Earth’s climate warm and habitable. There is also the “man-made” greenhouse effect, which is the enhancement of Earth’s natural greenhouse effect by the addition of greenhouse gases from the burning of fossil fuels (mainly petroleum, coal, and natural gas). In order to understand how the greenhouse effect operates, we need to first understand “infrared radiation”. Greenhouse gases trap some of the infrared radiation that escapes from the Earth, making the Earth warmer that it would otherwise be. You can think of greenhouse gases as sort of a “blanket” for infrared radiation– it keeps the lower layers of the atmosphere warmer, and the upper layers colder, than if the greenhouse gases were not there.

About 80-90% of the Earth’s natural greenhouse effect is due to water vapour, a strong greenhouse gas. The remainder is due to carbon dioxide, methane, and a few other minor gases.

It is the carbon dioxide concentration that is increasing, due to the burning of fossil fuels (as well as from some rainforest burning). This is the man-made portion of the greenhouse effect, and it is believed by many scientists to be responsible for the global warming of the last 150 years. Also, the concentration of methane, although small, has also increased in recent decades. The reasons for this increase, though, are uncertain.

2 The impact of Global warming

The impacts of global warming are already occurring in the Arctic with temperatures rising twice as fast as they are elsewhere in the world. This warming trend could greatly affect sea level rise, ocean circulation systems and salinity, and change marine habitats threatening many species with extinction.

Scientist’s project that melting of glaciers and land based arctic ice could raise sea level by as much as 3 feet by 2100, threatening low-lying coastal areas from the Gulf of Mexico and Florida to Bangladesh. Melting of the Greenland Ice Sheet could cause sea level to rise by as much as 23 feet. There are signs that this process has begun, although total melting is likely to take up to 1,000 years.

Polar bears could face extinction this century if the Arctic continues to melt at its present rate. The sea ice around the North Pole on which bears depend for hunting is shrinking rapidly. It could disappear during the summer months by the end of the century, impacting both wildlife and the local communities that depend upon them for subsistence, according to the Arctic Climate Impact Assessment commissioned by the Arctic Council, an intergovernmental body involving eight nations and six indigenous people’s organizations.

Melting arctic ice also threatens to disrupt the great ocean conveyor (Thermohaline Circulation System) which carries tremendous amounts of heat northward and enables the Earth to have temperatures suitable for human life over most of its surface. A recently released scientific study by Michael Schlesinger, a professor of atmospheric sciences at the University of Illinois, projects that without any effective climate change policy, there is a 45% probability that the ocean conveyor will shut down this century and a 70% chance it will shut down over the next 200 years.

This diagram shows the risk and impact of global warming in number II it shows the severity of global warming. At this present stage there is a risk but in 2040 there will be a large risk which will cause a lot of hurricanes for example round the coast of the USA

This image was from

3.1 Natural Factors affecting the climate

There are 5 factors which affect climate. These are summarised below:

Latitude :Temperature range increases with distance from the equator. Also, temperatures decrease as you move away from the equator. This is because the sun’s rays are dispersed over a larger area of land as you move away from the equator. This is due to the curved surface of the earth. In addition Polar Regions are colder because the suns rays have further to travel compared to place on the equator.

Altitude :Temperatures decrease with height. The air is less dense and cannot hold heat as easily.

Winds :If winds are warm – they have been blown from a hot area – they will raise temperatures. If winds have been blown from cold areas they will lower temperatures.

Distance from the sea (continentally): Land heats and cools faster than the sea. Therefore coastal areas have a lower temperature range than those areas inland. On the coast winters are mild and summers are cool. In inland areas temperatures are high in the summer and cold in the winter.

Aspect: Slopes facing the sun are warmer than those that are not. Thus south facing slopes in the northern hemisphere are usually warm whereas slopes facing north in the southern hemisphere are warmest

3.2 Human Factors affecting the climate

Enhancing the Greenhouse Effect: naturally occurring greenhouse gases, as described above, keep the Earth warm enough to support life. However, scientific studies have shown that a variety of human activities release greenhouse gases. These include the burning of fossil fuels for producing electrical energy, heating and transport. By increasing their concentrations and by adding new greenhouse gases like CFCs, humankind is capable of raising the average global temperature.

Land Use Change: As humans replace forests with agricultural lands, or natural vegetation with asphalt or concrete, they substantially alter the way the Earth’s surface reflects sunlight and releases heat. All these changes also affect regional evaporation, runoff and rainfall patterns. Land use and the changes in the way it is used effect the global carbon cycle, reduce the world’s forests and woodlands, expand the cropped land area, and cause tropical deforestation. As well, there is increased productivity of labor in exploiting land through the application of capital and new technologies. Conversion of land from natural to agricultural use also upsets the balance.

Atmospheric aerosols: Humans are adding large quantities of fine particles (aerosols) to the atmosphere, both from agriculture and industrial activities. Although most of these aerosols are soon removed by gravity and rainfall, they still affect the radiation balance in the atmosphere. Whether this effect adds to or offsets any warming trend depends on the quantity and nature of the particles as well as the nature of the land or ocean surface below. The regional effects, however, can be significant.

Burning of Fossil Fuels for Energy: As humanity burns the organic matter from past geologic periods (or the forests of today) to power the engines and economies of modern society, we are re-injecting our fossil carbon legacy into the atmosphere at incredibly accelerated rate. Carbon dioxide is dumped into the atmosphere at a much faster rate than it can be withdrawn or absorbed by the oceans or living things in the biosphere. The carbon dioxide buildup is a principal controlling factor of the climate change.

4 Arguments against global warming

Most scientists do not believe human activities threaten to disrupt the Earth’s climate. More than 17,000 scientists have signed a petition circulated by the Oregon Institute of Science and Medicine saying, in part, “there is no convincing scientific evidence that human release of carbon dioxide, methane, or other greenhouse gases is causing or will, in the foreseeable future, cause catastrophic heating of the Earth’s atmosphere and disruption of the Earth’s climate.” (Go to for the complete petition and names of signers.) Surveys of climatologists show similar scepticism.

Our most reliable sources of temperature data show no global warming trend. Satellite readings of temperatures in the lower troposphere (an area scientists predict would immediately reflect any global warming) show no warming since readings began 23 years ago. These readings are accurate to within 0.01�C, and are consistent with data from weather balloons. Only land-based temperature stations show a warming trend, and these stations do not cover the entire globe, are often contaminated by heat generated by nearby urban development, and are subject to human error.

Global climate computer models are too crude to predict future climate changes. All predictions of global warming are based on computer models, not historical data. In order to get their models to produce predictions that are close to their designers’ expectations, modellers resort to “flux adjustments” that can be 25 times larger than the effect of doubling carbon dioxide concentrations, the supposed trigger for global warming. Richard A. Kerr, a writer for Science, says “climate modellers have been ‘cheating’ for so long it’s almost become respectable.”

A modest amount of global warming, should it occur, would be beneficial to the natural world and to human civilization. Temperatures during the Medieval Warm Period (roughly 800 to 1200 AD), which allowed the Vikings to settle presently inhospitable Greenland, were higher than even the worst-case scenario reported by the IPCC. The period from about 5000-3000 BC, known as the “climatic optimum,” was even warmer and marked “a time when mankind began to build its first civilizations,” “There is good reason to believe that a warmer climate would have a similar effect on the health and welfare of our own far more advanced and adaptable civilization today.”

Efforts to quickly reduce human greenhouse gas emissions would be costly and would not stop Earth’s climate from changing. Reducing U.S. carbon dioxide emissions to 7 percent below 1990’s levels by the year 2012–the target set by the Kyoto Protocol–would require higher energy taxes and regulations causing the nation to lose 2.4 million jobs and $300 billion in annual economic output. Average household income nationwide would fall by $2,700, and state tax revenues would decline by $93.1 billion due to less taxable earned income and sales, and lower property values. Full implementation of the Kyoto Protocol by all participating nations would reduce global temperature in the year 2100 by a mere 0.14 degrees Celsius.

The information above was taken from


Deforestation is the term used for cutting down trees. Cutting down trees is bad because plants and trees convert carbon dioxide to oxygen by photosynthesis. If plants should get cut down means there will be more carbon dioxide and less oxygen, and the excess carbon dioxide will heat the earth more. According to Phillip Fearnside from the national institute for Amazonian research in Brazil said ‘The carbon emission in the area was too high’ (the area that they analysed already had wide tropical deforestation) ‘only about 0.6 to 1.0 billion tons of greenhouse gases (most carbon dioxide and carbon monoxide) were being produced by the razing and felling of tropical forests each year. This estimation is much lower than those of earlier studies, which estimated up to 2.4 billion tons annually’ this shows how deforestation from humans has changed by the production of more greenhouse gases. This is taken from

Hockey stick graph

The graph above is called a hockey stick graph because it has a sudden rise at the end of the graph. This graph shows a sharp rise since the industrial revolution, caused by increased CO2 in the earth’s levels from increased burning of fossil fuels by industry.

I took this image from the following website :


I strongly believe global warming was caused by man because we use chemical and produce chemicals which harm the earth we know is dangerous but we still ignored it. Example burning fossil fuels producing carbon dioxide which we know is bad we still burn them. Deforestation is another reason why global warming is man made because of the rate trees are being cut down. Trees take in carbon dioxide and gives out oxygen (photosynthesis) this process helps keep plants and humans alive. Global warming has serious consequence’s for example the health of humans, rising sea levels, extinction of animals and much more. We can help stop global warming for example recycling which reduces the amount of factories manufacturing the product and reducing distribution which means fewer Lorries. Another way humans try to reduce carbon is by using bio fuel for cars (instead of petrol) which is from plants to help reduce the amount of carbon dioxide.


These are the websites I went onto to investigate: