State some effects of a thinning ozone layer?

Question

State some effects of a thinning ozone layer

Answer 1

More Skin Cancers from increased Ultraviolet exposure.

Hotter world temperatures as more energy hits the earth.

some animals and plants will die due to more exposure to ultraviolet radiation.

Answer 2

THE OZONE LAYER:  IMPORTANT COMPONENTS OF OZONE EDUCATION

Joelle S. Busman

Cary Belen

  

INTRODUCTION

Donna:  What is the environment?

Martha:  The environment is the earth, and you have to help the earth.  Oh, and it�s the ozone layer.

Donna:  And what is the ozone layer?

Martha:  (shrugs her shoulders in a gesture of uncertainty) I think the ozone layer�s like the top of the air where we are right now and then the rest is empty of the ozone layer.  I think it�s supposed to protect where we are right now from polluting and trash and stuff.

Donna:  Where did you hear about the ozone layer?

Martha:  Mostly on TV�.The news channels mostly�.Sometimes I want to see what there is, what I should wear, but they go into the ozone layer and stuff, and I watch that until they say what the weather�s going to be like. (King, 78)

In the book, Doing their Share to Save the Planet, author Donna Lee King interviewed numerous children to ask their opinions about environmental issues.  The conversation above exhibits the innocence and naiveté of a young child, who will eventually inherit mother earth, in regards to the ozone layer.  Although the adult reader may chuckle at this young girl�s lack of knowledge, the average adult is virtually as uneducated.  With such a life affecting issue as the ozone layer, it is essential that society be well informed about the danger ozone depletion poses to earth.

There are many issues one must explore when educating himself/herself about the ozone layer.  The goal of this paper is to provide the layman with a general knowledge of important components of ozone education.  First, a general overview will be provided.  Next, the reader will learn scientific aspects of the ozone layer such as factors responsible for ozone depletion, and then he/she will explore the ozone hole over Antarctica.  To continue, societal aspects that will be addressed include health risks, crop/plant damage, and organism damage.  Finally, actions that government has taken to attempt to solve the problem will be discussed.  The paper will conclude with a discussion of the importance of ozone education.

SCIENTIFIC ASPECTS

The ozone layer:  What is it?

The ozone layer is a portion of earth�s atmosphere that contains high levels of ozone.  The atmosphere is divided into five layers:  the troposphere, the stratosphere, the mesosphere, the thermosphere, and the exosphere.  The troposphere is the layer closest to earth and is where all weather happenings occur.  The stratosphere is located directly above the troposphere, about 10-50 kilometers above the planet, and houses the ozone layer at an altitude of 20-30 kilometers.  The mesosphere is located approximately 50-80 kilometers above the earth, while the thermosphere rests at an altitude of approximately 100-200 kilometers above the earth�s surface.  Finally, the boundary of the outermost layer, the exosphere, extends roughly to 960-1000 kilometers above the earth.  For a visual of the lowermost three layers of our atmosphere, refer to Figure 1 below.

  

  

Figure 1:  Earth's atmosphere is divided into layers, which have various characteristics.

Source:  NOAA Aeronomy Laboratory, 1998

The ozone found in our atmosphere is formed by an interaction between oxygen molecules (composed of two oxygen atoms) and ultraviolet light. When ultraviolet light hits these oxygen molecules, the reaction causes the molecules to break apart into single atoms of oxygen (UV light + O2 --> O + O).  These single atoms of oxygen are very reactive, and a single atom combines with a molecule of oxygen to form ozone (O3), which is composed of three atoms of oxygen (2O + 2O2 --> 2O3).

The ozone layer is essential for human life.  It is able to absorb much harmful ultraviolet radiation, preventing penetration to the earth�s surface.  Ultraviolet radiation (UV) is defined as radiation with wavelengths between 290-320 nanometers, which are harmful to life because this radiation can enter cells and destroy the deoxyribonucleic acid (DNA) of many life forms on planet earth.  In a sense, the ozone layer can be thought of as a �UV filter� or our planet�s �built in sunscreen� (Geocities.com, 1998).  Without the ozone layer, UV radiation would not be filtered as it reached the surface of the earth.  If this happened, �cancer would break out and all of the living civilizations, and all species on earth would be in jeopardy� (Geocities.com, 1998).  Thus, the ozone layer essentially allows life, as we know it, to exist.

In order for scientists to evaluate how much ozone is in the layer, a unit of measurement called the Dobson Unit is employed.  A Dobson Unit is a measurement of how thick a specific portion of the ozone layer would be if it were compressed into a single layer at zero degrees Celsius with one unit of atmospheric pressure acting on it (standard temperature and pressure - STP). Thus, one Dobson Unit (DU) is defined as .01 mm thickness at standard temperature and pressure.  Figure 2 shows a column of air over Labrador, Canada.  Since the ozone layer over this area would form a 3 mm thick slab, the measurement of the ozone over Labrador is 300 DU.

Figure 2:  Ozone thickness over Labrador, Canada measured in Dobson Units

Source:  NASA, 1998

Ozone depletion:  Who is responsible?

It is important to recognize the sources of ozone depletion before one can fully understand the problem.  There are three main contributors to the ozone problem: human activity, natural sources, and volcanic eruptions (See Figure 3).

  

Figure 3:  Humans cause more damage to the ozone layer than any other source.

Source:  Geocities.com, 1998



Human activity is by far the most prevalent and destructive source of ozone depletion, while threatening volcanic eruptions are less common.  Human activity, such as the release of various compounds containing chlorine or bromine, accounts for approximately 75 to 85 percent of ozone damage.  Perhaps the most evident and destructive molecule of this description is chloroflourocarbon (CFC).  CFCs were first used to clean electronic circuit boards, and as time progressed, were used in aerosols and coolants, such as refrigerators and air conditioners.  When CFCs from these products are released into the atmosphere, the destruction begins.  As CFCs are emitted, the molecules float toward the ozone rich stratosphere.  Then, when UV radiation contacts the CFC molecule, this causes one chlorine atom to liberate.  This free chlorine then reacts with an ozone (O3) molecule to form chlorine monoxide (ClO) and a single oxygen molecule (O2).  This reaction can be illustrated by the following chemical equation:  Cl + O3 --> O2 + ClO.  Then, a single oxygen atom reacts with a chlorine monoxide molecule, causing the formation of an oxygen molecule (O2) and a single chlorine atom (O + ClO --> Cl + O2).  This threatening chlorine atom then continues the cycle and results in further destruction of the ozone layer (See Figure 4).  Measures have been taken to reduce the amount of CFC emission, but since CFCs have a life span of 20-100 years, previously emitted CFCs will do damage for years to come.

Figure 4:  A pictorial explanation of how the interaction of CFCs and UV radiation damage the ozone layer.

Source:  Geocities.com, 1998

Natural sources also contribute to the depletion of the ozone layer, but not nearly as much as human activity.  Natural sources can be blamed for approximately 15 to 20 percent of ozone damage.  A common natural source of ozone damage is naturally occurring chlorine.  Naturally occurring chlorine, like the chlorine released from the reaction between a CFC molecule and UV radiation, also has detrimental effects and poses danger to the earth.

Finally, volcanic eruptions are a small contributor to ozone damage, accounting for one to five percent.  During large volcanic eruptions, chlorine, as a component of hydrochloric acid (HCl), is released directly into the stratosphere, along with sulfur dioxide.  In this case, sulfur dioxide is more harmful than chlorine because it is converted into sulfuric acid aerosols.  These aerosols accelerate damaging chemical reactions, which cause chlorine to destroy ozone.

The ozone hole: Why over Antarctica?

When the topic of the ozone layer arises, many people immediately think of the hole over Antarctica, but few know why the hole is actually there.  In 1985, British scientists discovered this hole.  A special condition exists in Antarctica that accelerates the depletion of the ozone layer.  Every Arctic winter, a polar vortex forms over Antarctica.  A polar vortex is �a swirling mass of very cold, stagnant air surrounded by strong westerly winds� (Roan, 126).  Since there is an absence of sun during Arctic winters, the air becomes incredibly cold and the formation of ice clouds occurs.  When the sun returns in the spring, the light shining on the nitrogen oxide filled ice particles activates the formation of chlorine.  This excess of ozone destroying chlorine rapidly accelerates the depletion of the ozone layer.  Finally, when the polar vortex breaks up, the rapid dissolution decreases.  It is evident that the effects of the polar vortex are dramatic.  ÃƒÂ¯Ã‚¿Â½For about two month every southern spring, the total ozone declines by about 60% over most of Antarctica.  In the core of the ozone hole, more than 75% of the ozone is lost and at some altitudes, the ozone virtually disappeared in October, 1993� (Nilsson, 19).  The average size of the ozone hole is larger than most continents, including South America, Europe, Australia, and Antarctica, and the maximum size of the ozone hole in 1996 was larger than North America (See Figure 5).  Finally, one must note that the �hole� over Antarctica is truly a �hole� only in the Antarctic spring, when the depletion is extremely severe due to the vortex

Answer 3

Skin Cancers from suns UV rays!!!

Polar Bear extinction!!!

Other animal extinction!!!

Melted Antartica!!

Gllobal Warming!! No Duh!!

More Corn (corn grows in hot weather)!!

Floods(water ovrfils since ice melts)!!!

New york is going under water!!! part of flooding!!

More info:

Ozone depletion describes two distinct, but related observations: a slow, steady decline of about 4 percent per decade in the total amount of ozone in Earth's stratosphere since the late 1970s; and a much larger, but seasonal, decrease in stratospheric ozone over Earth's polar regions during the same period. The latter phenomenon is commonly referred to as the ozone hole. In addition to this well-known stratospheric ozone depletion, there are also tropospheric ozone depletion events, which occur near the surface in polar regions during spring.

The detailed mechanism by which the polar ozone holes form is different from that for the mid-latitude thinning, but the most important process in both trends is catalytic destruction of ozone by atomic chlorine and bromine.[1] The main source of these halogen atoms in the stratosphere is photodissociation of chlorofluorocarbon (CFC) compounds, commonly called freons, and of bromofluorocarbon compounds known as halons. These compounds are transported into the stratosphere after being emitted at the surface. Both ozone depletion mechanisms strengthened as emissions of CFCs and halons increased.

CFCs and other contributory substances are commonly referred to as ozone-depleting substances (ODS). Since the ozone layer prevents most harmful UVB wavelengths (270–315 nm) of ultraviolet light (UV light) from passing through the Earth's atmosphere, observed and projected decreases in ozone have generated worldwide concern leading to adoption of the Montreal Protocol banning the production of CFCs and halons as well as related ozone depleting chemicals such as carbon tetrachloride and trichloroethane. It is suspected that a variety of biological consequences such as increases in skin cancer, damage to plants, and reduction of plankton populations in the ocean's photic zone may result from the increased UV exposure due to ozone depletion.[citation needed]

Contents [hide]

1 Ozone cycle overview

1.1 Quantitative understanding of the chemical ozone loss process

2 Observations on ozone layer depletion

2.1 Chemicals in the atmosphere

2.1.1 CFCs in the atmosphere

2.2 Verification of observations

3 The ozone hole and its causes

3.1 Interest in ozone layer depletion

4 Consequences of ozone layer depletion

4.1 Increased UV

4.2 Biological effects of increased UV and microwave radiation from a depleted ozone layer

4.2.1 Effects of ozone layer depletion on Humans

4.2.2 Effects on Crops

4.2.3 Effects on Plankton

5 Public policy in response to the ozone hole

6 Current events and future prospects of ozone depletion

7 History of the research

7.1 The Rowland-Molina hypothesis

7.2 The Ozone Hole

8 Controversy regarding ozone science and policy

9 Ozone depletion and global warming

10 Misconceptions about ozone depletion

10.1 CFCs are "too heavy" to reach the stratosphere

10.2 Man-made chlorine is insignificant compared to natural sources

10.3 An ozone hole was first observed in 1956

10.4 If the theory were correct, the ozone hole should be above the sources of CFCs

10.5 The "ozone hole" is a hole in the ozone layer

11 World Ozone Day

12 See also

13 References

13.1 Nontechnical books

13.2 Books on public policy issues

13.3 Research articles

14 External links



[edit] Ozone cycle overview

Three forms (or allotropes) of oxygen are involved in the ozone-oxygen cycle: Oxygen atoms (O or atomic oxygen), oxygen gas (O2 or diatomic oxygen), and ozone gas (O3 or triatomic oxygen). Ozone is formed in the stratosphere when oxygen molecules photodissociate after absorbing an ultraviolet photon whose wavelength is shorter than 240 nm. This produces two oxygen atoms. The atomic oxygen then combines with O2 to create O3. Ozone molecules absorb UV light between 310 and 200 nm, following which ozone splits into a molecule of O2 and an oxygen atom. The oxygen atom then joins up with an oxygen molecule to regenerate ozone. This is a continuing process which terminates when an oxygen atom "recombines" with an ozone molecule to make two O2 molecules: O + O3 → 2 O2

The overall amount of ozone in the stratosphere is determined by a balance between photochemical production and recombination.

Ozone can be destroyed by a number of free radical catalysts, the most important of which are the hydroxyl radical (OH·), the nitric oxide radical (NO·) and atomic chlorine (Cl·) and bromine (Br·). All of these have both natural and anthropogenic (manmade) sources; at the present time, most of the OH· and NO· in the stratosphere is of natural origin, but human activity has dramatically increased the high in oxygen chlorine and bromine. These elements are found in certain stable organic compounds, especially chlorofluorocarbons (CFCs), which may find their way to the stratosphere without being destroyed in the troposphere due to their low reactivity. Once in the stratosphere, the Cl and Br atoms are liberated from the parent compounds by the action of ultraviolet light, e.g. ('h' is Planck's constant, 'ν' is frequency of electromagnetic radiation)

CFCl3 + hν → CFCl2 + Cl

The Cl and Br atoms can then destroy ozone molecules through a variety of catalytic cycles. In the simplest example of such a cycle,[2] a chlorine atom reacts with an ozone molecule, taking an oxygen atom with it (forming ClO) and leaving a normal oxygen molecule. A free oxygen atom then takes away the oxygen from the ClO, and the final result is an oxygen molecule and a chlorine atom, which then reinitiates the cycle. The chemical shorthand for these gas-phase reactions is:

Cl + O3 → ClO + O2

ClO + O → Cl + O2

The net reaction is: O3 + O → 2 O2, the "recombination" reaction given above.

The overall effect is to increase the rate of recombination, leading to an overall decrease in the amount of ozone. For this particular mechanism to operate there must be a source of O atoms, which is primarily the photo dissociation of O3; thus this mechanism is only important in the upper stratosphere where such atoms are abundant. More complicated mechanisms have been discovered that lead to ozone destruction in the lower stratosphere as well.

A single chlorine atom would keep on destroying ozone for up to two years (the time scale for transport back down to the troposphere) were it not for reactions that remove them from this cycle by forming reservoir species such as hydrogen chloride (HCl) and chlorine nitrate (ClONO2). On a per atom basis, bromine is even more efficient than chlorine at destroying ozone, but there is much less bromine in the atmosphere at present. As a result, both chlorine and bromine contribute significantly to the overall ozone depletion. Laboratory studies have shown that fluorine and iodine atoms participate in analogous catalytic cycles. However, in the Earth's stratosphere, fluorine atoms react rapidly with water and methane to form strongly-bound HF, while organic molecules which contain iodine react so rapidly in the lower atmosphere that they do not reach the stratosphere in significant quantities. Furthermore, a single chlorine atom is able to react with 100,000 ozone molecules. This fact plus the amount of chlorine released into the atmosphere by chlorofluorocarbons(CFCs) yearly demonstrates how dangerous CFCs are to the environment. [3]

[edit] Quantitative understanding of the chemical ozone loss process

New research on the breakdown of a key molecule in these ozone-depleting chemicals, dichlorine peroxide (Cl2O2), calls into question the completeness of present atmospheric models of polar ozone depletion. Specifically, chemists at NASA's Jet Propulsion Laboratory in Pasadena, California, found in 2007 that the temperatures, and the spectrum and intensity of radiation present in the stratosphere created conditions insufficient to allow the rate of chemical-breakdown required to release chlorine radicals in the volume necessary to explain observed rates of ozone depletion. Instead, laboratory tests, designed to be the most accurate reflection of stratospheric conditions to date, showed the decay of the crucial molecule almost a magnitude lower than previously thought[4].[5][6]

[edit] Observations on ozone layer depletion

The most pronounced decrease in ozone has been in the lower stratosphere. However, the ozone hole is most usually measured not in terms of ozone concentrations at these levels (which are typically of a few parts per million) but by reduction in the total column ozone, above a point on the Earth's surface, which is normally expressed in Dobson units, abbreviated as "DU". Marked decreases in column ozone in the Antarctic spring and early summer compared to the early 1970s and before have been observed using instruments such as the Total Ozone Mapping Spectrometer (TOMS).[7]



Lowest value of ozone measured by TOMS each year in the ozone holeReductions of up to 70% in the ozone column observed in the austral (southern hemispheric) spring over Antarctica and first reported in 1985 (Farman et al 1985) are continuing.[8] Through the 1990s, total column ozone in September and October have continued to be 40–50% lower than pre-ozone-hole values. In the Arctic the amount lost is more variable year-to-year than in the Antarctic. The greatest declines, up to 30%, are in the winter and spring, when the stratosphere is colder.

Reactions that take place on polar stratospheric clouds (PSCs) play an important role in enhancing ozone depletion.[9] PSCs form more readily in the extreme cold of Antarctic stratosphere. This is