Global Warming: Enhanced Greenhouse Effect

Enhanced greenhouse effect results in 'Global warming'. Greenhouses gases such as carbon dioxide, methane, nitrous oxide and chlorofluorocarbons (CFCs) trap the long-wave radiation from the Earth causing the atmosphere to excessive heat up. Water vapor is the most abundant greenhouse gas.(1) With time the rate of increasing atmospheric temperature is accelerating.

Natural Vs Human Enhanced Greenhouse Effect

Factors Behind Global Warming

Physical Factors and Global Warming

Changing Output of Solar Energy: Peaks of sunspot (Sunspots are areas where the magnetic field is about 2,500 times stronger than Earth's, much higher than anywhere else on the Sun) activity seem to raise global mean temperatures.

Volcanic Eruptions: After very violent eruptions, enormous quantities of volcanic dust particles are ejected high into the atmosphere. Global winds distribute the particles, therefore reducing temperatures by shielding the Earth from incoming insolation (total amount of solar radiation energy received on a given surface area during a given time).

Milankovitch Cycles: Variations in the Earth's eccentricity, axial tilt, and precession comprise the three dominant cycles, collectively known as the Milankovitch Cycles for Milutin Milankovitch, the Serbian astronomer and mathematician who is generally credited with calculating their magnitude. Taken in unison, variations in these three cycles creates alterations in the seasonality of solar radiation reaching the Earth's surface. These times of increased or decreased solar radiation directly influence the Earth's climate system, thus impacting the advance and retreat of Earth's glaciers.(2)

Human Factors and Global Warming

Deforestation: The clearance and burning of the rainforests for wood and farming land adds to the level of atmospheric CO2 by reducing photosynthesis.

Industrial Pollution: Before the Industrial Revolution, the greenhouse effect was a natural process. With the rise in industrial pollution, global warming has been increasing at a steady pace. Smoke and greenhouse gases are released by the factories into the air, which causes an increase in the greenhouse effect and increase in global warming. Melting of glaciers, extinction of polar beers, floods, tsunamis, hurricanes are few of the effects of global warming. Industrial smoke resulted in global warming where energy that is reflected cannot get past.

Nitrous Oxide: Automobile Vehicles have release nitrous oxide from their exhausts. Also produced by soil cultivation practices, especially the use of commercial and organic fertilizers, fossil fuel combustion, nitric acid production, and biomass burning. This pollution affects the ozone layer which help keep out much of the sun’s unwanted rays but all the pollution is making holes in it and letting more energy through.

CFCs: CFCs from aerosols and refrigerators have reacted with the ozone layer causing thinning and holes. Now largely regulated in production and release to the atmosphere by international agreement for their ability to contribute to destruction of the ozone layer. While emissions of these gases are less concentrated than their predecessors, they are potent, synthetic greenhouse gases. As a greenhouse gas, methane is 23 times more potent than carbon dioxide.(4)

Methane: A hydrocarbon gas produced both through natural sources and human activities, including the decomposition of wastes in landfills, agriculture, and especially rice cultivation, as well as ruminant digestion and manure management associated with domestic livestock. On a molecule-for-molecule basis, methane is a far more active greenhouse gas than carbon dioxide, but also one which is much less abundant in the atmosphere.

Consequences

• On average, Earth will become warmer. Air temperatures will rise between 1°C and 5°C.

• Global sea levels will rise, due to melting ice caps and water expansion as temperatures get warmer. Levels could rise 3.6m by 2100 meaning low lying, populated areas will be flooded e.g. The Nile. Fresh water will be contaminated and people will have to move. As many major cities are ports, they will be at great risk. For example, Tokyo, Venice and New Orleans.

• Warmer conditions will probably lead to more evaporation and precipitation overall, but individual regions will vary, some becoming wetter and others dryer. Intensity and frequency of tornadoes and hurricanes may increase. Tropical diseases such as malaria will move as warmer areas will expand.

• A stronger greenhouse effect will warm the oceans and partially melt glaciers and other ice, increasing sea level. Ocean water also will expand if it warms, contributing further to sea level rise.

Solutions

• Agriculture: Reduction in fertiliser use. Lower livestock ratio (animals per hectare) More environmentally-friendly farming e.g. organic.

• Transport: Improved engines to reduce emissions by 25% Increased tax on petrol Lower road-tax for cars with smaller engines.

• Industry: Stricter emission of all six greenhouse gases Better management of waste-tips and chemical processing.

• Energy: Develop wind, wave and solar power to replace nuclear power

Question: Is sulfur dioxide (SO2) a greenhouse gas?

Answer: No, sulfur dioxide is an aerosol that raises the Earth's albedo. It can cause a temporary cooling effect. Sulfur dioxide (SO2) emissions, mostly from burning coal, oil, and natural gas (sulfur emissions tend to have a net cooling effect).(3)

Question: Is ground-level ozone (O3) also a harmful gas?

Answer: Although the atmosphere includes a layer of ozone, ground-level ozone is harmful. Not only does it add to global warming, ground-level ozone is detrimental to human health by causing or worsening respiratory problems. In addition, it negatively impacts ecosystems by damaging vegetation.(4)

Notes: (1) A blanket around the Earth - http://climate.nasa.gov/causes/

(2) http://www.indiana.edu/~geol105/images/gaia_chapter_4/milankovitch.htm

(3) http://www.skepticalscience.com/graphics.php?g=57

(4) http://homeguides.sfgate.com/factories-pollution-other-causes-global-warming-78744.html

Sources:

• http://www.thestudentroom.co.uk/wiki/Revision:Global_Warming
• http://climate.nasa.gov/causes/
• http://www.conserve-energy-future.com