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Global Warming

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Felicia LeeBee

on 18 January 2014

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Transcript of Global Warming

photo credit Nasa / Goddard Space Flight Center / Reto Stöckli and
Climate Change Global Warming What are the Greenhouse Gases? How much have we increased the Atmosphere's CO2 Concentration? What is Global Warming and Climate Change? Climate change is the single biggest environmental and humanitarian crisis of our time. The Earth's atmosphere is overloaded with heat-trapping carbon dioxide, which threatens large-scale disruptions in climate with disastrous consequences Global Warming is the increase of Earth's average surface temperature due to effect of greenhouse gases, such as carbon dioxide emissions from burning fossil fuels or from deforestation, which trap heat that would otherwise escape from Earth. This is a type of greenhouse effect.
The most significant greenhouse gas is actually water vapor, not something produced directly by humankind in significant amounts. However, even slight increases in atmospheric levels of carbon dioxide (CO2) can cause a substantial increase in temperature.




There are two reasons:

First, although the concentrations of these gases are not nearly as large as that of oxygen and nitrogen (the main constituents of the atmosphere), neither oxygen or nitrogen are greenhouse gases. This is because neither has more than two atoms per molecule (i.e. their molecular forms are O2 and N2, respectively), and so they lack the internal vibrational modes that molecules with more than two atoms have. Both water and CO2, for example, have these "internal vibrational modes", and these vibrational modes can absorb and reradiate infrared radiation, which causes the greenhouse effect. Why is this? Secondly, CO2 tends to remain in the atmosphere for a very long time (time scales in the hundreds of years). Water vapor, on the other hand, can easily condense or evaporate, depending on local conditions. Water vapor levels therefore tend to adjust quickly to the prevailing conditions, such that the energy flows from the Sun and re-radiation from the Earth achieve a balance. CO2 tends to remain fairly constant and therefore behave as a controlling factor, rather than a reacting factor. More CO2 means that the balance occurs at higher temperatures and water vapor levels.
One of the first things scientists learned is that there are several greenhouse gases responsible for warming, and humans emit them in a variety of ways. Most come from the combustion of fossil fuels in cars, factories and electricity production. The gas responsible for the most warming is carbon dioxide, also called CO2. Other contributors include methane released from landfills and agriculture , nitrous oxide from fertilizers, gases used for refrigeration and industrial processes, and the loss of forests that would otherwise store CO2.
In order to understand the effects of all the gases together, scientists tend to talk about all greenhouse gases in terms of the equivalent amount of CO2. Since 1990, yearly emissions have gone up by about 6 billion metric tons of "carbon dioxide equivalent" worldwide, more than a 20 percent increase. Human beings have increased the CO2 concentration in the atmosphere by about thirty percent, which is an extremely significant increase, It is believed that human beings are responsible for this. Climate change is a complex phenomenon, and its full-scale impacts are hard to predict far in advance. But each year scientists learn more about how climate change is affecting the planet and our communities, and most agree that certain consequences are likely to occur if current trends continue.In addition to impacting our water resources, energy supply, transportation, agriculture, and ecosystems, the United States Global Change Research Program concludes that climate change also poses unique challenges to human health. Significant increases in the risk of illness and death related to extreme heat and heat waves are very likely.Some diseases transmitted by food, water, and insects are likely to increase. Why Should We Care? What can Be Done? Here's the good news: technologies exist today to make cars that run cleaner and burn less gas. We can also modernize power plants and generate electricity from nonpolluting sources as well as cut our electricity use through energy efficiency. The challenge is to be sure these solutions are put to use.
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