Tsunami-The Killer Wave

What is Tsunami?

“Tsunami” is a Japanese word in which “tsu” means harbor and “nami” means wave. Thus the word means “harbor wave.”

A tsunami is a series of waves of extremely long wavelength that are usually caused by a strong disturbance of the water, such as an underwater earthquake, landslide, or volcanic eruption, explosions, and even the impact of cosmic bodies, such as a meteorite can also cause a tsunami.

The waves travel outward in all directions from the disturbance, similar to what you would see if you threw a rock in a pond.

The average wave speed is 450 miles per hour.

Tsunami waves differ dramatically from traditional waves in that the tsunami waves have great depth, extending from the ocean floor the to water’s surface. The height above the water may be only a few inches, but the huge wave is actually “hidden” in the water below.

Traditional surface waves, such as those you would see at an ocean coastline, are shallow waves; they are caused by the gravitational pull of the moon, sun, and planets, or by wind.

Because of the great depth of the tsunami waves, when they hit the coastline their height may increase from a few inches to tens of feet. And the tremendous speed of the waves (about 500 miles per hour) can carry the tsunamis a great distance onto land, flooding areas, destroying structures, and injuring or killing people.

The sequence below illustrates how an underwater earthquake disturbs the water and causes a tsunami.

How do earthquakes generate Tsunamis?

Tsunamis can be generated when the sea floor abruptly deforms and vertically displaces the overlying water. Tectonic earthquakes are a particular kind of earthquakes that are associated with the earth's crustal deformation; when these earthquakes occur beneath the sea, the water above the deformed area is displaced from its equilibrium position. Waves are formed as the displaced water mass, which acts under the influence of gravity, attempts to regain its equilibrium. When large areas of the sea floor elevate or subside, a tsunami can be created.

Is it Possible to Prevent a Tsunami?

In a word, no. Once a tsunami has been formed, there is no way to stop it; but with an effective warning system in place, people can be evacuated.

And reducing the damage caused by a tsunami is certainly achievable. Tsunami walls, flood gates, and channels are three measures that can be taken to that end.

Japan is prone to tsunamis and has built numerous tsunami walls along the coast of heavily populated areas. The tsunami walls are designed to absorb some of the energy of the tsunami and redirect some of the water back towards the open ocean. The walls may be as high as 14 feet (see picture below).

Flood gates and channels can help redirect some of the incoming water from a tsunami, but a large tsunami will easily overwhelm any of the measures that are used to reduce its strength.

In pic=A tsuanami wall in Japan

What happens when a tsunami encounters land?
Just like other water waves, tsunamis begin to lose energy as they rush onshore - part of the wave energy is reflected offshore, while the shoreward-propagating wave energy is dissipated through bottom friction and turbulence. Despite these losses, tsunamis still reach the coast with tremendous amounts of energy. Tsunamis have great erosional potential, stripping beaches of sand that may have taken years to accumulate and undermining trees and other coastal vegetation. Capable of inundating, or flooding, hundreds of meters inland past the typical high-water level, the fast-moving water associated with the inundating tsunami can crush homes and other coastal structures. Tsunamis may reach a maximum vertical height onshore above sea level, often called a run up height, of 10, 20, and even 30 meters.


What should you do?
1. If you are at home and hear there is a tsunami warning, you should make sure your entire family is aware of the tsunami. Your family should evacuate your house if you live in a tsunami evacuation zone.

2. If you are at the beach or near the ocean and you feel the earth shake, move immediately to higher ground. Do not wait for a tsunami warning to be announced.

3. If you are on a ship or boat, do not return to port if you are at sea and a tsunami warning has been issued for your area. Tsunami can cause rapid changes in water level and unpredictable dangerous current in harbours and ports.

The Mega Tsunami

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Tsunami Footage

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Another Tsunami Footage

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Oceans Currents Behind Earth's Magnetism

Earth’s Magnetic field, long thought to be generated by molten metals swirling around its core, may instead be produced by ocean currents, according to controversial new research published last week.

It suggests that the movements of such volumes of salt water around the world have been seriously underestimated by scientists as a source of magnetism.

If proven, the research would revolutionize geophysics, the study of the Earth’s physical properties and behaviour, in which the idea that magnetism originates in a molten core is a central tenet. Earth’s magnetic field is vital for life, extending tens of thousands of miles into space and protecting the planet against radiation that would otherwise burn away the atmosphere and oceans. Image shows how Earth's Magnetic field saves Earth from Solar Wind..

However, its origin was a mystery until early last century when Albert Einstein said understanding the phenomenon was one of science’s most important tasks. This provoked a debate which concluded with scientists agreeing that magnetism must originate in the Earth’s core. “Everyone accepted this, but in reality there has never been any proof,” said Gregory Ryskin, associate professor of chemical and biological engineering at Northwestern University in Illinois. “It is just an idea we have accepted for a long time without questioning it enough.”

His research suggests that Earth’s magnetism is actually linked to ocean movements. The salt in seawater allows it to conduct electricity, meaning it generates electrical and magnetic fields as it moves. The findings, published by Britain’s Institute of Physics last week, are likely to cause a fierce scientific debate.

Existing theories explain Earth’s magnetism by suggesting that the centre of the planet comprises a white-hot solid iron ball about 1,500 miles in diameter, surrounded by an outer shell of liquid metal a further 1,400 miles thick. As the liquid iron in that shell is heated by the inner core it becomes less dense and rises upwards, to be replaced by cooler material from above. The resulting swirls of molten metal create electric currents that in turn produce the planet’s magnetic field, the conventional theory suggests.

Changes in ocean circulation may also, Ryskin said, explain the curious reversals shown by Earth’s magnetic field, in which the north and south magnetic poles have suddenly flipped over. This last happened 780,000 years ago. If Gregory Ryskin is right, then Climate Change, predicted to alter the strength and course of ocean currents, could also alter the planet’s magnetic field.
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Climate Change Turning Seas Acid

Climate change is turning the oceans more acid in a trend that could endanger everything from clams to coral and be irreversible for thousands of years, national science academies said.

"To avoid substantial damage to ocean ecosystems, deep and rapid reductions of carbon dioxide emissions of at least 50 percent (below 1990 levels) by 2050, and much more thereafter, are needed," the academies said in a joint statement.

The academies said rising amounts of carbon dioxide, the main greenhouse gas emitted mainly by human use of fossil fuels, were being absorbed by the oceans and making it harder for creatures to build protective body parts. The shift disrupts ocean chemistry and attacks the "building blocks needed by many marine organisms, such as corals and shellfish, to produce their skeletons, shells and other hard structures", it said.

On some projections, levels of acidification in 80 percent of Arctic seas would be corrosive to clams that are vital to the food web by 2060, it said. And "coral reefs may be dissolving globally," it said, if atmospheric levels of carbon dioxide were to rise to 550 parts per million (ppm) from a current 387 ppm.
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Truth Behind the Fact...

Increasing use of fossil fuels means more carbon dioxide is going into the air, and most of it will eventually be absorbed by seawater. Once in the water, it reacts to form carbonic acid.

This, in turn, reduces the amount of calcium carbonate in the ocean -- which turns out to be a chemical widely used by marine life.

The acidification of the oceans will ultimately be a temporary state that naturally corrects itself over time. But as we keep pumping CO2 into the sky and the chemistry of the oceans have to keep adjusting to deal with the carbonic acid, life in the oceans could suffer serious decline. The changes occurring in the ocean today are truly extraordinary.This needs immediate attention.

Corals are home to many species of fish. These changes in ocean chemistry are irreversible for many thousands of years, and the biological consequences could last much longer. As acid levels rise in the surface waters, Feeley said, many species of plankton and other creatures at the base of the marine food chain can't develop properly because of the acid-caused decline in calcium carbonate.

Calcification decreases significantly,Many of these species are the primary food sources for juvenile salmon and other important species for mankind. We may be having a very significant impact on the food web.

Most organisms live near the surface, where the greatest pH change would be expected to occur, but deep-ocean lifeforms may be more sensitive to pH changes.

"Coral reefs are like the rain forests of the ocean," noted co-author Chris Langdon, a coral expert at the University of Miami. Acidification of seawater undermines the skeletal structures of coral, Langdon said, which in turn undermines this basic marine ecosystem and harms other species that have evolved to depend upon it.

Coral reefs and other organisms whose skeletons or shells contain calcium carbonate may be particularly affected, the team speculate. They could find it much more difficult to build these structures in water with a lower pH.
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The warning was issued by the Inter-Academy Panel, representing science academies of countries from Albania to Zimbabwe and including those of Australia, Britain, France, Japan and the United States. Martin Rees, president of the Royal Society, the British science academy, said there may be an "underwater catastrophe".

The effects will be seen worldwide, threatening food security, reducing coastal protection and damaging the local economies that may be least able to tolerate it.

In recent years some people have suggested deliberately storing carbon dioxide from power stations in the deep ocean as a way of curbing global warming.

Previously, most experts had looked at ocean absorption of carbon dioxide as a good thing - because in releasing CO2 into the atmosphere we warm the planet; and when CO2 is absorbed by the ocean, it reduces the amount of greenhouse warming.

The academies' statement said that, if current rates of carbon emissions continue until 2050, computer models indicate that "the oceans will be more acidic than they have been for tens of millions of years".

It also urged actions to reduce other pressures on the oceans, such as pollution and over-fishing.
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Now Agriculture could be part of solution to global warming

A new report released by the Worldwatch Institute, Washington has said that agriculture could become a big part of the solution to global warming.

According to a report in Environmental News Network (ENN), innovations in food production and land use that are ready to be put to work could reduce greenhouse gas emissions equivalent to roughly 25 percent of global fossil fuel emissions and be managed to reduce carbon already in the atmosphere as well.

Carbon capture technology remains unproven and will take a decade at least to put into operation.

By contrast, agricultural and land use management practices that are ready today could be employed to sequester carbon through photosynthesis by growing and sustaining more plants.

"To understand how and why the agricultural approach to climate change must be a part of the solution, the public first needs to recognize that the world must "go negative" with carbon emissions - producing fewer than it churns out to reach the necessary reductions by 2050," said Sara Scherr, co-author with Sajal Sthapit of the report, Mitigating Climate Change Through Food and Land Use.

Policymakers must go beyond improving energy efficiency and scaling up renewables and add ways to pull down emissions from forestry and agriculture operations.

The report outlines five ways to reduce and sequester carbon using farming strategies.

They are - enriching soil carbon, farming with perennials, climate-friendly livestock production, protecting natural habitat, and, restoring degraded watersheds and range lands.
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i-MiEV: Zero-emission car to hit roads soon

The world's first mass-produced zero-emission minicar, the "i-MiEV", is all set to debut in Japan next month, which promises to usher in a new age of driving that does not require fossil fuel.

i-MiEV Car

Developed by the Mitsubishi Motors Corporation, the car has neither an engine nor a muffler and does not need an internal combustion engine because it runs on a motor
charged with electricity.

The i-MiEV can travel 160 kilometers on its lithium-ion battery pack, but it will take 14 hours to fully recharge the battery from a 100-volt household power outlet.

i-MiEV Car

It emits no carbon dioxide. Even when taking into account CO2 emissions at the power plants that generate the power needed for charging the car, it emits only about one-third of the CO2 of a gasoline minicar.

Save Water. Save Life...

Population growth means people are using more and more water every day. In most parts of the country, voluntary conservation is the water-wise way to live. Here are some ways you can put a stopper in your water-wasteful ways:

INDOORS

1. Never put water down the drain when there may be another use for it such as watering a plant or garden, or cleaning.
2. Verify that your home is leak-free, because many homes have hidden water leaks. Read your water meter before and after a two-hour period when no water is being used. If the meter does not read exactly the same, there is a leak.
3. Repair dripping faucets by replacing washers. If your faucet is dripping at the rate of one drop per second, you can expect to waste 2,700 gallons per year which will add to the cost of water and sewer utilities, or strain your septic system.
4. Check for toilet tank leaks by adding food coloring to the tank. If the toilet is leaking, color will appear within 30 minutes. Check the toilet for worn out, corroded or bent parts. Most replacement parts are inexpensive, readily available and easily installed. (Flush as soon as test is done, since food coloring may stain tank.)
5. Avoid flushing the toilet unnecessarily. Dispose of tissues, insects and other such waste in the trash rather than the toilet.
6. Take shorter showers. Replace you showerhead with an ultra-low-flow version. Some units are available that allow you to cut off the flow without adjusting the water temperature knobs.
7. Use the minimum amount of water needed for a bath by closing the drain first and filling the tub only 1/3 full. Stopper tub before turning water. The initial burst of cold water can be warmed by adding hot water later.
8. Don't let water run while shaving or washing your face. Brush your teeth first while waiting for water to get hot, then wash or shave after filling the basin.
9. Retrofit all wasteful household faucets by installing aerators with flow restrictors.
10. Operate automatic dishwashers and clothes washers only when they are fully loaded or properly set the water level for the size of load you are using.
11. When washing dishes by hand, fill one sink or basin with soapy water. Quickly rinse under a slow-moving stream from the faucet.
12. Store drinking water in the refrigerator rather than letting the tap run every time you want a cool glass of water.
13. Do not use running water to thaw meat or other frozen foods. Defrost food overnight in the refrigerator or by using the defrost setting on your microwave.
14. Kitchen sink disposals require lots of water to operate properly. Start a compost pile as an alternate method of disposing food waste instead of using a garbage disposal. Garbage disposals also can add 50% to the volume of solids in a septic tank which can lead to malfunctions and maintenance problems.
15. Consider installing an instant water heater on your kitchen sink so you don't have to let the water run while it heats up. This will reduce heating costs for your household.
16. Insulate your water pipes. You'll get hot water faster plus avoid wasting water while it heats up.
17. Never install a water-to-air heat pump or air-conditioning system. Air-to-air models are just as efficient and do not waste water.
18. Install water softening systems only when necessary. Save water and salt by running the minimum amount of regenerations necessary to maintain water softness. Turn softeners off while on vacation.
19. Check your pump. If you have a well at your home, listen to see if the pump kicks on and off while the water is not in use. If it does, you have a leak.
20. When adjusting water temperatures, instead of turning water flow up, try turning it down. If the water is too hot or cold, turn the offender down rather than increasing water flow to balance the temperatures.
21. If the toilet flush handle frequently sticks in the flush position, letting water run constantly, replace or adjust it.

OUTDOORS

1. Don't over water your lawn. As a general rule, lawns only need watering every 5 to 7 days in the summer and every 10 to 14 days in the winter. A hearty rain eliminates the need for watering for as long as two weeks. Plant it smart, Xeriscape. Xeriscape landscaping is a great way to design, install and maintain both your plantings and irrigation system that will save you time, money and water. For your free copy of "Plant it Smart," an easy-to-use guide to Xeriscape landscaping, contact your Water Management District.
2. Water lawns during the early morning hours when temperatures and wind speed are the lowest. This reduces losses from evaporation.
3. Don't water your street, driveway or sidewalk. Position your sprinklers so that your water lands on the lawn and shrubs ... not the paved areas.
4. Install sprinklers that are the most water-efficient for each use. Micro and drip irrigation and soaker hoses are examples of water-efficient methods of irrigation.
5. Regularly check sprinkler systems and timing devices to be sure they are operating properly. It is now the law that "anyone who purchases and installs an automatic lawn sprinkler system MUST install a rain sensor device or switch which will override the irrigation cycle of the sprinkler system when adequate rainfall has occurred." To retrofit your existing system, contact an irrigation professional for more information.
6. Raise the lawn mower blade to at least three inches. A lawn cut higher encourages grass roots to grow deeper, shades the root system and holds soil moisture better than a closely-clipped lawn.
7. Avoid over fertilizing your lawn. The application of fertilizers increases the need for water. Apply fertilizers which contain slow-release, water-insoluble forms of nitrogen.
8. Mulch to retain moisture in the soil. Mulching also helps to control weeds that compete with plants for water.
9. Plant native and/or drought-tolerant grasses, ground covers, shrubs and trees. Once established, they do not need to be watered as frequently and they usually will survive a dry period without any watering. Group plans together based on similar water needs.
10. Do not hose down your driveway or sidewalk. Use a broom to clean leaves and other debris from these areas. Using a hose to clean a driveway can waste hundreds of gallons of water.
11. Outfit your hose with a shut-off nozzle which can be adjusted down to fine spray so that water flows only as needed. When finished, "Turn it Off" at the faucet instead of at the nozzle to avoid leaks.
12. Use hose washers between spigots and water hoses to eliminate leaks.
13. Do not leave sprinklers or hoses unattended. Your garden hoses can pour out 600 gallons or more in only a few hours, so don't leave the sprinkler running all day. Use a kitchen timer to remind yourself to turn it off.
14. Check all hoses, connectors and spigots regularly.
15. Consider using a commercial car wash that recycles water. If you wash your own car, park on the grass to do so.
16. Avoid the installation of ornamental water features (such as fountains) unless the water is recycled. Locate where there are mineral losses due to evaporation and wind drift.
17. If you have a swimming pool, consider a new water-saving pool filter. A single back flushing with a traditional filter uses from l80 to 250 gallons or more of water

GENERAL

1. Create an awareness of the need for water conservation among your children. Avoid the purchase of recreational water toys which require a constant stream of water.
2. Be aware of and follow all water conservation and water shortage rules and restrictions which may be in effect in your area.
3. Encourage your employer to promote water conservation at the workplace. Suggest that water conservation be put in the employee orientation manual and training program.
4. Patronize businesses which practice and promote water conservation.
5. Report all significant water losses (broken pipes, open hydrants, errant sprinklers, abandoned free-flowing wells, etc.) to the property owner, local authorities or your Water Management District.
6. Encourage your school system and local government to help develop and promote a water conservation ethic among children and adults.
7. Support projects that will lead to an increased use of reclaimed waste water for irrigation and other uses.
8. Support efforts and programs to create a concern for water conservation among tourists and visitors to our state. Make sure your visitors understand the need for, and benefits of, water conservation.
9. Encourage your friends and neighbors to be part of a water conscious community. Promote water conservation in community newsletters, on bulletin boards and by example.
10. Conserve water because it is the right thing to do. Don't waste water just because someone else is footing the bill such as when you are staying at a hotel.
11. Try to do one thing each day that will result in a savings of water. Don't worry if the savings is minimal. Every drop counts. And every person can make a difference. So tell your friends, neighbors and co-workers to "Turn it Off" and "Keep it Off".

Saving water in small ways really adds up by the end of the day. . .



Do one thing every day that will save water. Every drop counts.

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Ozone Layer and it's depletion..

The ozone layer is a layer in Earth's atmosphere which contains relatively high concentrations of ozone (O3). This layer absorbs 93-99% of the sun's high frequency ultraviolet light, which is potentially damaging to life on earth. Over 91% of the ozone in Earth's atmosphere is present here. It is mainly located in the lower portion of the stratosphere from approximately 10 km to 50 km above Earth, though the thickness varies seasonally and geographically.

Ultraviolet light and ozone
UV radiation is divided into three categories, based on its wavelength; these are referred to as UV-A (400-315 nm), UV-B (315-280 nm), and UV-C (280-100 nm). UV-C, which would be very harmful to humans, is entirely screened out by ozone at around 35 km altitude. UV-B radiation can be harmful to the skin and is the main cause of sunburn; excessive exposure can also cause genetic damage, resulting in problems such as skin cancer. The ozone layer is very effective at screening out UV-B; for radiation with a wavelength of 290 nm, the intensity at Earth's surface is 350 billion times weaker than at the top of the atmosphere. Nevertheless, some UV-B reaches the surface. Most UV-A reaches the surface; this radiation is significantly less harmful, although it can potentially cause genetic damage.

Ozone Depletion
The ozone layer is a layer of gas in the upper atmosphere which protects humans and other living things from the harmful ultraviolet (UV-B) rays of the sun. In the 1970s scientists discovered that certain man-made chemicals could destroy ozone and deplete the ozone layer. Further research found that the growing production and use of chemicals like chlorofluorocarbons (CFCs) in aerosol sprays, refrigeration, insulation and air conditioning was contributing to the accumulation of ozone-depleting substances (ODS) in the atmosphere. They also observed that an ‘ozone hole’ was developing above the Antarctic.

The Ozone Hole and its causes
The Antarctic ozone hole is an area of the Antarctic stratosphere in which the recent ozone levels have dropped to as low as 33% of their pre-1975 values. The ozone hole occurs during the Antarctic spring, from September to early December, as strong westerly winds start to circulate around the continent and create an atmospheric container. Within this polar vortex, over 50% of the lower stratospheric ozone is destroyed during the Antarctic spring.

the overall cause of ozone depletion is the presence of chlorine-containing source gases (primarily CFCs and related halocarbons). In the presence of UV light, these gases dissociate, releasing chlorine atoms, which then go on to catalyze ozone destruction. The Cl-catalyzed ozone depletion can take place in the gas phase, but it is dramatically enhanced in the presence of polar stratospheric clouds (PSCs).

Consequences of ozone layer depletion
A>Increased UV
Ozone, while a minority constituent in the earth's atmosphere, is responsible for most of the absorption of UVB radiation. The amount of UVB radiation that penetrates through the ozone layer decreases exponentially with the slant-path thickness/density of the layer. Correspondingly, a decrease in atmospheric ozone is expected to give rise to significantly increased levels of UVB near the surface.

B>Biological effects of increased UV and microwave radiation from a depleted ozone layer
The main public concern regarding the ozone hole has been the effects of surface UV on human health. So far, ozone depletion in most locations has been typically a few percent and, as noted above, no direct evidence of health damage is available in most latitudes. Were the high levels of depletion seen in the ozone hole ever to be common across the globe, the effects could be substantially more dramatic. As the ozone hole over Antarctica has in some instances grown so large as to reach southern parts of Australia and New Zealand, environmentalists have been concerned that the increase in surface UV could be significant.

C>Effects of ozone layer depletion on humans
UVB (the higher energy UV radiation absorbed by ozone) is generally accepted to be a contributory factor to skin cancer. In addition, increased surface UV leads to increased tropospheric ozone, which is a health risk to humans.[citation needed] The increased surface UV also represents an increase in the vitamin D synthetic capacity of the sunlight.

The cancer preventive effects of vitamin D represent a possible beneficial effect of ozone depletion. In terms of health costs, the possible benefits of increased UV irradiance may outweigh the burden.

D>Effects on crops
An increase of UV radiation would be expected to affect crops. A number of economically important species of plants, such as rice, depend on cyanobacteria residing on their roots for the retention of nitrogen. Cyanobacteria are sensitive to UV light and they would be affected by its increase.

E>Effects on plankton
Research has shown a widespread extinction of plankton 2 million years ago that coincided with a nearby supernova. There is a difference in the orientation and motility of planktons when excess of UV rays reach earth. Researchers speculate that the extinction was caused by a significant weakening of the ozone layer at that time when the radiation from the supernova produced nitrogen oxides that catalyzed the destruction of ozone (plankton are particularly susceptible to effects of UV light, and are vitally important to marine food webs).

Ozone Depletion and Global Warming

Although they are often interlinked in the mass media, the connection between global warming and ozone depletion is not strong. There are five areas of linkage:
• The same CO2 radiative forcing that produces near-surface global warming is expected to cool the stratosphere. This cooling, in turn, is expected to produce a relative increase in polar ozone (O3) depletion and the frequency of ozone holes.
• Conversely, ozone depletion represents a radiative forcing of the climate system. There are two opposing effects: Reduced ozone causes the stratosphere to absorb less solar radiation, thus cooling the stratosphere while warming the troposphere; the resulting colder stratosphere emits less long-wave radiation downward, thus cooling the troposphere. Overall, the cooling dominates; the IPCC concludes that "observed stratospheric O3 losses over the past two decades have caused a negative forcing of the surface-troposphere system"of about −0.15 ± 0.10 watts per square meter (W/m²).
• One of the strongest predictions of the greenhouse effect is that the stratosphere will cool.Although this cooling has been observed, it is not trivial to separate the effects of changes in the concentration of greenhouse gases and ozone depletion since both will lead to cooling. However, this can be done by numerical stratospheric modeling. Results from the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory show that above 20 km (12.4 miles), the greenhouse gases dominate the cooling.
• Ozone depleting chemicals are also greenhouse gases. The increases in concentrations of these chemicals have produced 0.34 ± 0.03 W/m² of radiative forcing, corresponding to about 14% of the total radiative forcing from increases in the concentrations of well-mixed greenhouse gases.
• The long term modeling of the process, its measurement, study, design of theories and testing take decades to both document, gain wide acceptance, and ultimately become the dominant paradigm. Several theories about the destruction of ozone, were hypothesized in the 1980s, published in the late 1990s, and are currently being proven. Dr Drew Schindell, and Dr Paul Newman, NASA Goddard, proposed a theory in the late 1990s, using a SGI Origin 2000 supercomputer, that modeled ozone destruction, accounted for 78% of the ozone destroyed. Further refinement of that model, accounted for 89% of the ozone destroyed, but pushed back the estimated recovery of the ozone hole from 75 years to 150 years. (An important part of that model is the lack of stratospheric flight due to depletion of fossil fuels.)

Montreal Protocol
The Montreal Protocol on Substances That Deplete the Ozone Layer is an international treaty designed to protect the ozone layer by phasing out the production of a number of substances believed to be responsible for ozone depletion.
The treaty is structured around several groups of halogenated hydrocarbons that have been shown to play a role in ozone depletion. All of these ozone depleting substances contain either chlorine or bromine (substances containing fluorine-only do not harm the ozone layer).


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