Downloaded 146 times
More Related Content
Similar to GLoBal WaRmiNg..
GLoBal WaRmiNg..
- 2.
- 4. Global Warming...... What isGlobal Warming? 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. Is global warming, caused by human activity, even remotely plausible? Earth's climate is mostly influenced by the first 6 miles or so of the atmosphere which contains most of the matter making up the atmosphere. This is really a very thin layer if you think about it. In the book The End of Nature, author Bill McKibbin tells of walking three miles to from his cabin in the Adirondack's to buy food. Afterwards, he realized that on this short journey he had traveled a distance equal to that of the layer of the atmosphere where almost all the action of our climate is contained. In fact, if you were to view Earth from space, the principle part of the atmosphere would only be about as thick as the skin on an onion! Realizing this makes it more plausible to suppose that human beings can change the climate. A look at the amount of greenhouse gases we are spewing into the atmosphere (see below), makes it even more plausible.
- 5. MatterOf Concern.... The rapidrise in greenhouse gases is a problem because it is changing the climate faster than some living things may be able to adapt. Also, a new and more unpredictable climate poses unique challenges to all life. Now, with concentrations of greenhouse gases rising, Earth’s remaining ice sheets (such as Greenland and Antarctica) are starting to melt too.The extra water could potentially raise sea levels significantly. As the mercury rises, the climate can change in unexpected ways. In addition to sea levels rising, weather can become more extreme. Scientists are already seeing some of these changes occurring more quickly than they had expected. According to the Intergovernmental Panel on Climate Change, eleven of the twelve hottest years since thermometer readings became available occurred between 1995 and 2006.
- 7. Causes.... What Causes GlobalWarming? Scientists have spent decades figuring out what is causing global warming.They’ve looked at the natural cycles and events that are known to influence climate. But the amount and pattern of warming that’s been measured can’t be explained by these factors alone.The only way to explain the pattern is to include the effect of greenhouse gases (GHGs) emitted by humans. Different greenhouse gases have very different heat-trapping abilities. Some of them can even trap more heat than CO2. A molecule of methane produces more than 20 times the warming of a molecule of CO2. Nitrous oxide is 300 times more powerful than CO2. Other gases, such as chlorofluorocarbons (which have been banned in much of theworld because they also degrade the ozone layer), have heat-trapping potential thousands of times greater than CO2. But because their concentrations are much lower than CO2, none of these gases adds as much warmth to the atmosphere as CO2 does
- 9. Greenhouse Effect.... The “greenhouseeffect” is the warming that happens when certain gases in Earth’s atmosphere trap heat.These gases let in light but keep heat from escaping, like the glass walls of a greenhouse. First, sunlight shines onto the Earth’s surface, where it is absorbed and then radiates back into the atmosphere as heat. In the atmosphere, “greenhouse” gases trap some of this heat, and the rest escapes into space.The more greenhouse gases are in the atmosphere, the more heat gets trapped. Scientists often use the term “climate change” instead of global warming.This is because as the Earth’s average temperature climbs, winds and ocean currents move heat around the globe in ways that can cool some areas, warm others, and change the amount of rain and snow falling.As a result, the climate changes differently in different areas.
- 10. Greenhouse Gases...... What arethe Greenhouse Gases? 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. Why is this? 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. 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.
- 11. Effects..... Sea levelsare expected to rise between 7 and 23 inches (18 and 59 centimeters) by the end of the century, and continued melting at the poles could add between 4 and 8 inches (10 to 20 centimeters). Hurricanes and other storms are likely to become stronger. Polar bear biologist Ian Stirling has found a similar pattern in Hudson Bay. He fears that if sea ice disappears, the polar bears will as well. The decline of the Adélie penguins on Antarctica, where their numbers have fallen from 32,000 breeding pairs to 11,000 in 30 years. Sea level rise became faster over the last century. Ecosystems will change—some species will move farther north or become more successful; others won’t be able to move and could become extinct.
- 12. Etymology.... The termglobal warming was first used in its modern sense on 8 August 1975 in a science paper byWally Broecker in the journal Science called "Are we on the brink of a pronounced global warming?". Broecker's choice of words was new and represented a significant recognition that the climate was warming; previously the phrasing used by scientists was "inadvertent climate modification," because while it was recognized humans could change the climate, no one was sure which direction it was going.The National Academy of Sciences first used global warming in a 1979 paper called the Charney Report, it said: "if carbon dioxide continues to increase, we find no reason to doubt that climate changes will result and no reason to believe that these changes will be negligible."The report made a distinction between referring to surface temperature changes as global warming, while referring to other changes caused by increased CO2 as climate change. Global warming became more widely popular after 1988 when NASA climate scientist James Hansen used the term in a testimony to Congress. He said: "global warming has reached a level such that we can ascribe with a high degree of confidence a cause and effect relationship between the greenhouse effect and the observed warming." His testimony was widely reported and afterward global warming was commonly used by the press and in public discourse.
- 13. The Earth isShouting for Life Save It.....
- 14. SolutionsTo It.... A commonlycited goal is to stabilize GHG concentrations around 450-550 parts per million (ppm), or about twice pre-industrial levels.This is the point at which many believe the most damaging impacts of climate change can be avoided. Current concentrations are about 380 ppm, which means there isn’t much time to lose. According to the IPCC, we’d have to reduce GHG emissions by 50% to 80% of what they’re on track to be in the next century to reach this level. In addition to reducing the gases we emit to the atmosphere, we can also increase the amount of gases we take out of the atmosphere. Plants and trees absorb CO2 as they grow, “sequestering” carbon naturally. Increasing forestlands and making changes to the way we farm could increase the amount of carbon we’re storing. Some of these technologies have drawbacks, and different communities will make different decisions about how to power their lives, but the good news is that there are a variety of options to put us on a path toward a stable climate.