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Global Warming

By Alfonso de Garay
      March 21, 2014


Table of contents:

- Increased greenhouse gases in the Earth´s atmosphere
- The greenhouse effect
- Ozone Depletion
- The Effects of Global Warming

Increased greenhose gases in the Earth´s atmosphere

The average temperatures of the Earth´s atmosphere, surface, and oceans have been increasing since the last part of 19th century [1]. Moreover, the growth rate of the Earth´s surface temperature doubled in the second part of the 20th century. 
 
This physical phenomenon has been described as the result of both man-made and non-man-made emissions of greenhouse gases into the atmosphere, initiating a process in which the absorption and emission of infrared radiation by these gases raises the temperatures of the Earth´s atmosphere, surface, and oceans. It seems to be the consensus in the scientific community that global warming is the result of increased greenhouse gases [2] in the Earth´s atmosphere.
 
The Greenhouse Effect
 
The greenhouse effect occurs when solar energy passes through the atmosphere and is absorbed by the Earth´s surface, which then re-radiates about half of that energy back into the atmosphere as thermal (infrared) radiation. There, some of the radiation is absorbed by greenhouse gases [3] and re-emitted to the atmosphere and to the Earth surface.
 
Because part of the thermal radiation is returned to the lower atmosphere and to the Earth´s surface, the Earth´s surface warms, increasing the average temperature.  Among the more relevant gases involved in the greenhouse effect are water vapor, carbon dioxide, methane, and ozone [4].
 
 
World industrialization has increased the emissions of greenhouse gases, mainly carbon dioxide (CO2); methane (CH4); ozone (O3); chlorofluorocarbons, know as CFCs; and nitrous oxide. Together, these gases have forced the radiation absorption and emission process—known as global warming--that has warmed the Earth.
 
In the last three decades, concentration levels of CO2 in the atmosphere have rapidly risen. Currently, CO2 in the atmosphere is at the highest historic level that has been scientifically recorded. These higher CO2 levels have been generated mainly by human activity [5] through the burning of fossil fuels—coal, oil, and gas-- although other factors, such as deforestation, have also contributed to increasing CO2 levels in the atmosphere. 
 
Ozone Depletion
 
Ozone depletion is the destruction of the stratospheric layer of ozone [6] by chlorofluorocarbons. This is a different process, not directly related to global warming. Although the destruction of the ozone layer in the stratosphere has had a minor cooling effect on the Earth’s surface, the increase in tropospheric ozone has produced a more noticeable warming effect.
 
 
The Effects of Global Warming
 
Scientists have been attempting a process known as detection to find statistically significant facts that show that climate is changing, without attributing an explanation of this change. They are also attempting to find the most probable causes of climate change,[7] a process known as attribution.
 
 
The global warming to date has been measured as approximately a 0.55 °C increase in the Earth’s average annual  temperature, [8] as compared to what it was before the year 1960.

This temperature increase has been accompanied by measurable effects, [9] such as a rise in sea levels (because as the temperature of sea water increases, its volume expands), a lowering of  snow and ice levels, a decreasing volume of Arctic ice,  and a contraction of glaciers.

 

Climate Models and Global Warming into the 21st Century
 
The scientific community is studying the warming in climate systems, using computer climate models [10] that generate scenarios to predict how global warming might affect the world by the end of the 21st century.
 
There is basic agreement among the international community that political, economic, and technological measures should be taken now to reduce the growth rate of global warming, in order to limit the increase in the average annual earth temperature to less than 2°C, as compared to the average world temperatures recorded before 1850.
 
Some computer models find that if, by the end of this century, the average surface temperature of the Earth deviates more than 2°C over that of  pre-industrial levels,  there could be considerable physical and social implications.
 
In fact, the global warming effects might already be noticeable. [11] In the last decade, for example, the Earth’s mean temperatures in some years [12] were among the highest ever recorded,
 
There are several global warming and climate change [13] scenarios from different organizations, using different computer simulation models, and producing distinct outcomes. If global temperatures continue to increase during the 21st century, the range of sea level rise could  vary from about 0.5- 2.0 meters to as much as 4 meters, depending on  the greenhouse effects assumed by each  model, and each model’s  projections of average land and sea temperatures by the end of the century.
 
For all of Earth’s continents, the models predict that global warming will produce extreme weather conditions, [14] including extended desertification, increased number and strength of hurricanes, extreme rainfall on river deltas, and greater surf. In addition, increased sea levels will submerge many islands, causing some to completely disappear. These warming effects will result in the displacement and migration of entire populations, with serious consequences for many regions of  the Earth.


La Crosse Technologies WS-2811BRN-IT Wireless Weather Pro Center (WS-2811BRN-IT)

 References:
 
[1] NRDC, Natural Resources Defense Council. “Global Warning”.<http://www.nrdc.org/globalwarming/> 11 January 2014.
 
[2] Union of Concerned Scientists. “Global Warming: Confronting the Realities of Climate Change”. <http://www.ucsusa.org/global_warming/> 13 January 2014.
 
[3] EPA, United States Environment Protection Agency.“Overview of Greenhouse Gases”17/04/2014.<http://www.epa.gov/climatechange/ghgemissions/gases/fgases.html> 15 January 2014.

 
[4] Hyperphysics.
“Thermodynamics”.

<http://hyperphysics.phy-astr.gsu.edu/HBASE/thermo/grnhse.html> 10 February 2014.
 
[5] Clean air kids organization.uk. “Greenhouse effect & Global Warming”.
<http://www.clean-air-kids.org.uk/globalwarming.html> 20 February 2014.
 
[6] U.S. Environment Protection Agency. “The Science of Ozone Layer Depletion”. <http://www.epa.gov/ozone/science/> 21 Febuary 2014
 
[7] National Aeronautics and Space Administration. “Global Climate Change Vital Signs of the Planet”. <http://climate.nasa.gov/climate_resource_center> 24 Febuary 2014.
 
[8] ippc, Intergovernmental Panel on Climate Change. Climate Change 2007: Working Group I: The Physical Science Basis.“TS.3.1.1 Global Average Temperatures”. <https://www.ipcc.ch/publications_and_data/ar4/wg1/en/tssts-3-1-1.html> 2 March 2014.
 
[9] NOAA, National Climatic Data Center. National Oceanic and Atmospheric Administration. “Global Analysis November 2013”. <http://www.ncdc.noaa.gov/sotc/global/2013/11> 5 March 2014.
 
[10] David Archer. Global Warming. “Understanding The Forecast, January 2014”. <http://forecast.uchicago.edu/> 10 March 2014.
 
[11] Artic Change. National Oceanic and Atmospheric Administration. “Global Temperatures Trends: 2013 Summation”. <http://www.arctic.noaa.gov/detect/global-temps.shtml> 15 March 2014.
 
[12] EPA, United States Environment Protection Agency. “Future Climate Change”. <http://www.epa.gov/climatechange/science/future.html> 15 March 2014.
 
13] La Crosse Technology Weather Station."Global Warming".<http://www.lacrossetechnologyweatherstation.com/Climate_Change.html> 20 March 2014.

[14] GFDL, Geophysics Fluid Dynamics Laboratory. “Climate Change, Variability and Prediction”.<http://www.gfdl.noaa.gov/climate-change-variability-and-prediction> 19 March 2014.