Stratospheric Ozone Depletion: Treaties, Environmental Indicators, and Na tional Responses

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Stratospheric Ozone Depletion: Treaties, Environmental Indicators, and National Responses

Nature of the Stratospheric Ozone Depletion Issue

Ozone levels in the atmosphere undergo normal seasonal variations, but recent levels of ozone loss over the poles and lower latitudes cannot be explained by natural variability alone. Man-made CFC compounds were developed in the early 1930s for a variety of industrial and commercial applications, but it was not until the 1970s that these and other chlorine-containing substances were suspected of having the potential to destroy atmospheric ozone. In 1985 a team of British researchers first reported unusually low ozone levels over Halley Bay, Antarctica, which were caused by chemical reactions with chlorine and nitrogen compounds. Research was initiated that found CFCs to be largely responsible for the anomalously low levels during the polar springtime. This polar ozone depletion at lower stratospheric altitudes is what has been termed the "ozone hole." The primary concern over ozone depletion is the potential impacts on human health and ecosystems due to increased UV exposure. Increases in skin cancer and cataracts in human populations are expected in a higher UV environment. Lower yields of certain cash crops may result due to increased UV-B stress. Higher UV-B levels in the upper ocean layer may inhibit phytoplankton activities, which can impact the entire marine ecosystem. In addition to direct biological consequences, indirect effects may arise through changes in atmospheric chemistry. Increased UV-B will alter photochemical reaction rates in the lower atmosphere that are important in the production of surface layer ozone and urban smog.

Concern over these potential effects has prompted the international community to enact policies aimed at reducing the production of ozone-depleting chemicals. An important event in the history of international ozone policy was the Montreal Protocol on Substances That Deplete the Ozone Layer (1987), which called for the phaseout and reduction of certain substances over a multiyear time frame. Discoveries of more extensive ozone loss and rapid formulation of replacement substances for chlorine-containing compounds have led to refinements of the original Protocol. Updates set forth at London (1990) and Copenhagen (1992) have called for accelerated phaseout and replacement schedules.

Satellite remote sensing of ozone has played a large part in verifying ozone depletion by providing researchers a relatively long-term and continual picture of the global ozone environment from which statistical trends in ozone levels can be derived. The longest running and best known of the ozone satellite instruments is the National Aeronautical and Space Administration's (NASA) Total Ozone Mapping Spectrometer (TOMS). This instrument was in operation for almost 14 years beginning December 1978, and provided daily snapshots of total column ozone thickness that covered almost the entire globe. Downward trends in ozone levels derived from data from this instrument provided impetus for the accelerated phaseout schedules of CFCs set forth at the Copenhagen conference. Continuing daily coverage of global ozone levels is provided through the National Oceanic and Atmospheric Administration's (NOAA) Tiros Operational Vertical Sounder (TOVS) instrument. In 1991, NASA launched another TOMS instrument on board a Russian Meteor-3 satellite, which provided concurrent measurements until the original TOMS ultimate demise in May 1993. Meteor-3/TOMS remained operational through December 1994. NASA plans to launch the Earth Probe/TOMS in the summer of 1996 to re-establish global coverage of total column ozone for continuing studies of the Earth's atmosphere. For more information on TOMS and access to the TOMS data archives, see the TOMS home page.

CIESIN's thematic guide on ozone depletion and global environmental change provides an overview of key concepts and issues related to ozone depletion.

International Environmental Treaties Related to the Ozone Depletion Issue

The Montreal Protocol on Substances That Deplete the Ozone Layer is a landmark international agreement designed to protect the stratospheric ozone layer. The treaty was originally signed in 1987 and substantially amended in 1990 and 1992. The Montreal Protocol stipulates that the production and consumption of compounds that deplete ozone in the stratosphere--chlorofluorocarbons (CFCs), halons, carbon tetrachloride, and methyl chloroform--are to be phased out by 2000 (2005 for methyl chloroform). Methyl bromide (MB), an ozone-depleting compound used extensively in agricultural applications, is set to be phased out internationally by 2010.

The framework for the Montreal Protocol was based on the Vienna Convention for the Protection of the Ozone Layer (1985), a non-binding agreement which outlined states' responsibilities for protecting human health and the environment against the adverse effects of ozone depletion.

Linkages between ozone depletion treaties and key indicators

The discussion of issues related to stratospheric ozone depletion has led to the identification of key indicators for measuring the state of ozone depletion as it relates to the development of international treaties. The Pressure-State-Response framework is used here to explain the linkages among international treaties, key indicators, and national response strategies. Key indicators for stratospheric ozone depletion tend to overlap in this type of framework and may fall into more than one category, but descriptions will be provided in the most relevant area. The primary pressure indicators in the area of ozone depletion are the global production levels of ozone-depleting substances (ODPs). These include chlorofluorocarbons (CFCs) such as CFC-11, CFC-12, CFCs 113, 114, and 115, halogenated compounds such as halon-1301, and methyl bromide. State indicators in the ozone issue include current and historical levels of atmospheric ozone, and the derived trends in ozone over the globe. Data measurements and trends in atmospheric chlorine concentrations are another example of state indicators. Response indicators revolve around policy development and risk assessment activities; these include, for example, international agreements as set forth by the Montreal Protocol, and national strategies to reduce the potential impact of ozone depletion and ultraviolet radiation exposure such as the UV Index, which is routinely broadcast in the United States, Canada, and European countries. This section also points to remote sensing data relevant to the identified indicators.

PRESSURE INDICATORS: PRODUCTION AND SUPPLY OF OZONE-DEPLETING SUBSTANCES

The production and supply of ozone-depleting substances has fallen significantly over the past few years following the inception of the Montreal Protocol and its subsequent amendments at London andCopenhagen, which called for even more aggressive phaseout schedules than originally developed. With the approaching deadlines of the protocol and the continuing development of economical replacements for ozone-depleting substances, production and supply is likely to continue decreasing through the end of the century.

Indicators

Production of ozone-depleting substances
Phasing out of ozone-depleting substances

Data/Data Source

Data on the global production of ozone-depleting substances is provided by the Alternative Fluorocarbon Environmental Acceptability Study (AFEAS).

Import of CFCs and Halons in ODP tons

The London Amendment to the Montreal Protocol and the Copenhagen Agreement provides phasing-out data on ozone-depleting substances.

Treaty relevance

The Montreal Protocol on Substances That Deplete the Ozone Layer is a landmark international agreement designed to protect the stratospheric ozone layer. The treaty was originally signed in 1987 and substantially amended in 1990 (London) and 1992 (Copenhagen). The Montreal Protocol stipulates that the production and consumption of compounds that deplete ozone in the stratosphere--chlorofluorocarbons (CFCs), halons, carbon tetrachloride, and methyl chloroform--are to be phased out by 2000 (2005 for methyl chloroform). Additional information on this topic is available at CIESIN's Thematic Guide on Political Institutions and Global Environmental Change.
The Montreal Protocol on Substances That Deplete the Ozone Layer considered global controls of methyl bromide since 1995. Methyl bromide phaseout information is available from the United States Environmental Protection Agency (EPA) at their methyl bromide home page.

National response

The national goals of Norway for reducing the consumption of ozone depleting substances are in accordance with those specified in the Montreal Protocol.
Several nations are already planning to phase out Methyl Bromide including the U.S., the Netherlands, Sweden, Canada, and Denmark. The Netherlands eliminated all soil fumigation uses in 1992 due to ground water concerns. Denmark will eliminate all use of methyl bromide by 1998, and Sweden is expected to adopt a similar policy. If Parties to the Montreal Protocol agree to additional years of methyl bromide use in developing countries, a clear mechanism should be identified to prevent MB manufacturers from using this "grace period" to vastly increase their sales and production in southern nations, thus encouraging dependence on methyl bromide. Requirements for methyl bromide phaseout as given by the Montreal Protocol, in addition to several other topical questions concerning methyl bromide are discussed at the EPA's methyl bromide home page.

STATE INDICATORS: ATMOSPHERIC CONCENTRATION OF OZONE-DEPLETING SUBSTANCES

Indicators

Key indicators in this area are atmospheric concentrations of ozone-depleting substances. These compounds are measured at ground level at several locations around the globe to monitor the global distribution of ODP's in the lower atmosphere. Upper atmospheric measurements of chlorine- and bromine-containing compounds have recently been measured, providing direct evidence that links these compounds to ozone loss in the stratosphere.

Data/Data Source

Global production of the primary ozone-depleting chlorofluorocarbons (CFC-11, CFC-12, CFC-113, CFC-114, CFC-115) through 1993 are available online through CIESIN's thematic guide on ozone depletion:
Long-term time series data on the atmospheric concentration of CFC-11 and CFC-12 from several monitoring stations around the world are provided at the National Oceanic and Atmospheric Administration's (NOAA) Climate Monitoring and Diagnostics Laboratory (CMDL).
Measurements of HCl and HF in the stratosphere by the Halogen Occulation Experiment (HALOE) instrument on board NASA's Upper Atmosphere Research Satellite (UARS) that link CFC emissions with ozone loss are described at the HALOE website.

Treaty relevance

Atmospheric monitoring of ozone-depleting substance levels provides an indication of compliance of the global community to the regulations set forth by the Montreal Protocol and its amendments, and on the effectiveness of the phaseout limits defined by the treaty. The measure of compliance and effectiveness of the treaty was indicated in a report by researchers at the NOAA in 1993, in which they reported a decrease in the growth rates of atmospheric CFC-11 and CFC-12 levels. This slowdown in the growth rate was directly attributed to the policy regulations set forth by the Montreal Protocol. More recently, scientists have found that atmospheric levels of another ozone-depleting substance, methyl chloroform, have decreased since 1991. This is the first instance that a substance regulated by the Montreal Protocol has been found to be decreasing, lending more credibility to the effectiveness of the provisions set forth in the protocol.

National response

See the ENTRI query interface for a list of signatories to the Montreal Protocol.
UCAR's SOLIS--Stratospheric Ozone Law, Information & Science--a guide to ozone science and national and international policy information.

STATE INDICATORS: STRATOSPHERIC OZONE LEVELS

Indicators

Key indicators in this area are total column ozone measurements, which provide the total amount of ozone in a column from the surface to the top of the atmosphere, and vertical profiles, which provide information on the altitude distribution of ozone in the atmosphere.

Data/Data Source

TOMS Home Page -- home of the TOMS total column ozone archives from Nimbus-7 and Meteor-3 satellites. Also contains lots of other information about ozone, the atmosphere, and planned flights of future TOMS instruments.
TOVS total ozone analyses -- provides near real-time total column ozone maps for the entire globe as measures by TOVS. Also provides map and data archives, as well as software to read the data.
Ozone Soundings at Neumayer -- ozone sounding images and data from the Neumayer Antarctic station (Denmark) from 1992 to present; ozone soundings at Georg Forster station from 1985 is also available.
British Antarctic Survey: Ozone at Faraday and Halley -- ozone measurements provided by the British Antarctic Survey (BAS) from their Halley Bay and Faraday stations.
HALOE Home Page -- data and information on the Halogen Occultation Experiment (HALOE), an instrument on board NASA's Upper Atmosphere Research Satellite (UARS) that measures stratospheric concentrations of ozone and ozone-depleting substances.

Treaty relevance

In November 1992, growing fears over the potential impacts of ozone depletion led to the Copenhagen Agreement, which commits governments to a total phase-out of the most destructive CFCs by the year 1996. This will help to protect the ozone layer and reduce the role of CFCs in climate change, although the benefits of these agreements will not be felt for several years due to the long life-span of CFCs.

RESPONSE INDICATORS: ENVIRONMENTAL AND HEALTH IMPACTS

Indicators

defining indicators in the area of environmental and human health impacts related to ozone depletion are difficult due to the complexity of defining a quantifiable dose-response relationship between ultraviolet radiation exposure and biological response. For example, it is known that long-term exposure to sunlight is a risk factor in developing non-melanoma skin cancer in humans, but the specific time frame or amount of UV radiation required to induce these cancers is unknown. Similarly in plants, it is known that certain species are susceptible to increases in UV exposure under controlled laboratory conditions, but competing stresses under natural conditions, such as soil moisture, nutrient availability, and air quality may mask the true impact of UV radiation under natural ecosystem conditions. For more information on potential health impacts of UV exposure on terrestrial and aquatic ecosystems as well as human health, see the following resources:
- Thematic Guide on Ozone Depletion and Global Environmental Change
- Health Effects of Overexposure to the Sun (EPA)

National response

UNITED STATES

In response to the potential threat of increased ultraviolet exposure to human health due to decreasing ozone levels, the National Weather Service (NWS) in conjunction with the United States Environmental Protection Agency (EPA) have developed the "UV Index", a forecasted value which gives an indication of how intense the ultraviolet exposure is expected to be the following day. This program was initiated in 1994. With this information, the general public can take precautionary measures to reduce their level of UV exposure, and thereby reduce their risk of developing 1-related health effects. The latest UV index can be found at NOAA's Climate Prediction Center.

CANADA

Canada was the first country to implement a UV index forecast, beginning in 1992. Daily forecasts for Canada are provided by Environment Canada.

EUROPE

Several countries in Europe promote the use of UV index forecasts. European maps of the UV index can be found through the State of the Environment Norway web space.

Treaty Texts

Summaries

ENTRI