GLOBAL WARMiNG & OZONE

DEPLETiONGROUP MEMBERS:

Arabiran, NadineCadisal. Valerie-Jade

Dela Pena, Trisha MarieMorete, Cindy Grace

*JACiTRiDiNE*

Global WarmingGlobal warming is the teused to describe a gradual increase in the average temperature of the Earth's

atmosphere and its oceans, a change that is rm believed to be permanently changing the Earth’s

climate forever. While many view the effects of global warming to be more substantial and more rapidly

occurring than others do, the scientific consensus on climatic changes related to global warming is that the average temperature of the Earth has risen between 0.4 and 0.8 °C over the past 100 years. The increased

volumes of carbon dioxide and other greenhouse gases released by the burning of fossil fuels, land

clearing, agriculture, and other human activities, are believed to be the primary sources of the global

warming that has occurred over the past 50 years.

triviaScientists from the

Intergovernmental Panel on Climate carrying out global warming research have recently predicted that average global temperatures could increase between 1.4 and 5.8 °C by the

year 2100. Changes resulting from global warming may include rising sea levels due to the melting of the polar ice caps, as well as an increase in occurrence and severity of storms and other severe weather events.

Causes of Global

Warming*Carbon Dioxide from Power

Plants In 2002 about 40% of U.S. carbon dioxide emissions stem from the burning of fossil fuels for the purpose

of electricity generation. Coal accounts for 93 percent of the emissions from the electric utility

industry. Coal emits around 1.7 times as much carbon per unit of energy when

burned as does natural gas and 1.25 times as much as oil. Natural gas gives off 50% of the carbon

dioxide, the principal greenhouse gas, released by coal and 25% less carbon dioxide than oil, for the same amount of energy produced. Coal contains about 80 percent more carbon per unit of energy than gas does, and oil contains about 40 percent

more.

Carbon Dioxide Emitted from Cars

- About 33% of U.S carbon dioxide emissions comes from the burning of gasoline in internal-combustion engines of cars and light trucks (minivans, sport utility vehicles, pick-up trucks, and jeeps)

Carbon Dioxide from Airplanes

- The UN's Intergovernmental Panel on Climate Change estimates that aviation causes 3.5 percent of global warming, and that the figure could rise to 15 percent by 2050.

Water Vapor in the Atmosphere Increasing

- Water vapor is the most prevalent

and most poweful greenhouse gas on the planet, but its increasing presence is the result of warming caused by carbon dioxide, methane and other greenhouse gases. (See NOAA's National Climate Data Center (NCDC) FAQ page) Water vapor holds onto two-thirds of the heat trapped by all the greenhouse gases

DeforestationAfter carbon emissions caused by humans, deforestation is the second principle cause of atmospheric carbon dioxide. Deforestation is responsible for 20-25% of all carbon emissions entering the atmosphere, by the burning and cutting of about 34 million acres of trees each year. We are losing millions of acres of rainforests each year, the equivalent in area to the size of Italy.

OTHERS … The main human activities that

contribute to global warming are the burning of fossil fuels (coal, oil, and natural gas).

The clearing of land. Most of the burning occurs in automobiles, in factories, and in electric power plants that provide energy for houses and office buildings.

The burning of fossil fuels creates carbon dioxide, whose chemical formula is CO2. CO2 is a greenhouse gas that slows the escape of heat into space. Trees and other plants remove CO2 from the air during photosynthesis, the process they use to produce food.

Impact of Global Warming Continued global warming could have

many damaging effects. It might harm plants and animals that live in the sea.

It could also force animals and plants on land to move to new habitats.

Weather patterns could change, causing flooding, drought, and an increase in damaging storms.

Global warming could melt enough polar ice to raise the sea level. In certain parts of the world, human disease could spread, and crop yields could decline.

ADVANTAGES AND DiSADVANTAGES OF GLOBAL WARMiNG

ADVANTAGES: Arctic, Antarctic, Siberia, and other frozen

regions of earth may experience more plant growth and milder climates.

The next ice age may be prevented from occurring.

Northwest Passage through Canada's formerly-icy north opens up to sea transportation.

Less need for energy consumption to warm cold places.

Fewer deaths or injuries due to cold weather. Longer growing seasons could mean increased

agricultural production in some local areas. Mountains increase in height due to melting

glaciers, becoming higher as they rebound against the missing weight of the ice.

DiSADVANTAGES: Ocean circulation disrupted, disrupting and having unknown effects on world

climate. Higher sea level leading to flooding of low-lying lands and deaths and disease

from flood and evacuation. Deserts get drier leaving to increased desertification. Changes to agricultural production that can lead to food shortages. Water shortages in already water-scarce areas. Starvation, malnutrition, and increased deaths due to food and crop shortages. More extreme weather and an increased frequency of severe and

catastrophic storms. Increased disease in humans and animals. Increased deaths from heat waves. Extinction of additional species of animals and plants. Loss of animal and plant habitats. Increased emigration of those from poorer or low-lying countries to wealthier or

higher countries seeking better (or non-deadly) conditions. Additional use of energy resources for cooling needs. Increased air pollution. Increased allergy and asthma rates due to earlier blooming of plants. Melt of permafrost leads to destruction of structures, landslides, and avalanches. Permanent loss of glaciers and ice sheets. Cultural or heritage sites destroyed faster due to increased extremes. Increased acidity of rainfall. Earlier drying of forests leading to increased forest fires in size and intensity. Increased cost of insurance as insurers pay out more claims resulting from

increasingly large disasters. 

Ozone Layer Depletion

What is Ozone Layer Depletion?

It is a crucial environmental problem on Earth. The growing concern over CFC production and the hole in the ozone layer is causing alarm among scientists and citizens. A battle has ensued to protect Earth's ozone layer.

Ozone is a gas that occurs naturally in our atmosphere. Most of it is concentrated in the ozone layer, a region located in the stratosphere several miles above the surface of the Earth. Although ozone represents only a small fraction of the gas present in the atmosphere, it plays a vital role by shielding humans and other life from harmful ultraviolet light from the Sun.

How does Ozone Layer Depletion Occur?

It is caused by the release of chlorofluorocarbons (CFCs), hydrofluorocarbons (HCFCs), and other ozone-depleting substances (ODS), which were used widely as refrigerants, insulating foams, and solvents. The discussion below focuses on CFCs, but is relevant to all ODS. Although CFCs are heavier than air, they are eventually carried into the stratosphere in a process that can take as long as 2 to 5 years. Measurements of CFCs in the stratosphere are made from balloons, aircraft, and satellites.

When CFCs and HCFCs reach the stratosphere, the ultraviolet radiation from the sun causes them to break apart and release chlorine atoms which react with ozone, starting chemical cycles of ozone destruction that deplete the ozone layer. One chlorine atom can break apart more than 100,000 ozone molecules.

Other chemicals that damage the ozone layer include methyl bromide (used as a pesticide), halons (used in fire extinguishers), and methyl chloroform (used as a solvent in industrial processes for essential applications). As methyl bromide and halons are broken apart, they release bromine atoms, which are 60 times more destructive to ozone molecules than chlorine atoms.

Will the ozone layer recover? Can we make more ozone to fill

in the hole? Provided that we stop producing

ozone-depleting substances, ozone will be created through natural processes that should return the ozone layer to normal levels by about 2050. It is very important that the world comply with the Montreal Protocol; delays in ending production could result in additional damage and prolong the ozone layer's recovery.

What is being done to stop ozone depletion?

Replacing the CFCs and other Ozone Depleting Substances with environmentally safe substances. Researches are going on for identifying the best alternative substances ; presently HCFCs (hydrochlorofluorocarbons, substances containing hydrogen, chlorine, fluorine, carbon) are replacing CFCs, being much less harmful for the ozone layer. In the future, HCFCs will be phased out, too.

The "Montreal Protocol" is the 1987 international treaty governing the protection of stratospheric ozone agreement to phase out the Ozone Depleting Substances.According to the Montreal Protocol ( and successive amendments) usage of the CFCs and most Halons have been reduced or phased out; other ODS, like HCFCs, will be phased out in the future .

Montreal Protocol was without doubt a great success for the environment, clearly reducing the total amount of chlorine and bromine entering the atmosphere. Those reductions should first arrest the decline, then allow the ozone layer to rebuild. Anyway, even if the consumption of all ODS gases would  be completely discontinued,  it will take a lot of years before complete recovering of the ozone layer,  due to their persistence in the atmosphere.

Ozone is Earth’s natural sunscreen, absorbing most of the incoming ultraviolet (UV) radiation from the sun and protecting life from DNA-damaging radiation. Chlorofluorocarbons (CFCs for short)—invented in the early 1890s and first used in the 1930s as refrigerants and propellants for chemical sprays—are ozone destroyers.Earlier this year, a team of NASA-led scientists set out to predict what the ozone layer would have looked like today and in the future if countries around the world had not signed the Montreal Protocol Treaty banning ozone-depleting chemicals. This series of images shows ozone concentrations over the mid-latitudes of the Western Hemisphere, based on months of calculations by the Goddard Earth Observing System Chemistry-Climate Model.By 2020, the model predicts that an ozone “hole”—concentrations below 220 Dobson Units—forms over the Arctic as well as the Antarctic. By 2040, the ozone hole is global. The UV index in mid-latitude cities reaches 15 around noon on a clear summer day (10 is considered extreme today). By the end of the model run, global ozone drops to less than 110 Dobson Units, a 67 percent drop from the 1970s.

Effects of Ozone Layer Depletion(a) Harm to human health:

* More skin cancers, sunburns and premature aging of the skin.

* More cataracts, blindness and other eye diseases: UV radiation can damage several parts of the eye, including the lens, cornea, retina and conjunctiva.

* Cataracts (a clouding of the lens) are the major cause of blindness in the world. A sustained 10% thinning of the ozone layer is expected to result in almost two million new cases of cataracts per year, globally.

* Weakening of the human immune system (immunosuppression). Early findings suggest that too much UV radiation can suppress the human immune system, which may play a role in the development of skin cancer.

Adverse impacts on agriculture, forestry and

natural ecosystems: * Several of the world’s major crop species are particularly vulnerable to increased UV, resulting in reduced growth, photosynthesis and flowering. Many agricultural crops are sensitive to the burning rays of the sun, including the world’s main food crops, rice, wheat, corn and soyabean.

* Many species of crops like sweet corn, soyabean, barley, oats, cow peas, carrots, cauliflower, tomato, cucumber, peas and broccoli are highly sensitive to UV-B radiation. As a result, food production could be reduced by 10% for every 1% increase of UV-B radiation.

* The effect of ozone depletion on the Indian agricultural sector could be significant.

* Only a few commercially important trees have been tested for UV (UV-B) sensitivity, but early results suggest that plant growth, especially in seedlings, is harmed by more intense UV radiation.

Damage to marine life: * In particular, plankton (tiny organisms on the

surface layer of oceans) are threatened by increased UV radiation. Plankton are the first vital step in aquatic food chains.

* Decreases in plankton could disrupt the fresh and saltwater food chains, and lead to a species shift.

* Species of marine animals in their growing stage, including young fish, shrimp larvae and crab larvae, have been threatened in recent years by the growing UV-B radiation under the Antarctic ozone hole. Loss of biodiversity in our oceans, rivers and lakes could reduce fish yields for commercial and sport fisheries.

Animals: * In domestic animals, UV over

exposure may cause eye and skin cancers.

* Materials: Wood, plastic, rubber, fabrics and many construction materials are degraded by UV radiation.

* The economic impact of replacing and/or protecting materials could be significant.

THE END !