Where is the ozone layer depleted the most

In the chart we see the magnitude of global decline in ODS consumption since This data measures the indexed consumption of ODS to the i. In the chart we see the quantity of ODS consumption by country. This is measured in tonnes of ozone-depleting substances all weighted relative to their depleting potential. By clicking on a country on the map, you can view a time-series of how its national consumption has changed over this period.

The trends in consumption above have been aggregated to total consumption of ODS. This quantifies the aggregate of a number of substances. In the chart we see the breakdown of consumption by substance.

Note that, as with other measures throughout this entry, each substance has been weighted by its potential to destroy ozone. At the global level we see the trend of declining consumption — as established above — since Throughout the s and first half of the s, chlorofluorocarbons CFCs dominated global consumption accounting for 60 percent, reducing to 50 percent.

However, through the s we have seen a rising dominance of hydrochlorofluorocarbons HCFCs ; in HCFCs accounted for 94 percent of global consumption.

This replacement was therefore been an important reduction strategy particularly where the complete phase-out of ozone depleting substances was not readily available. Chlorofluorocarbons CFCs have almost been completely phased out, declining from over , tonnes in to tonnes in The rapid decline in emissions of ozone-depleting substances shown above was driven by international agreement to phase out their production.

In the Vienna Convention for the Protection of the Ozone Layer was adopted and entered into force in In the chart we see the evolution of global parties signing on to the Vienna Convention. In its first year there were only 29 parties signed to the agreement.

This rapidly increased in the years to follow, reaching parties by In , the Vienna Convention became the first of any Convention to achieve universal ratification. The Vienna Convention, despite not mandating parties to take concrete actions on ozone protection laid the foundations for adoption of The Montreal Protocol.

The Montreal Protocol on Substances that Deplete the Ozone Layer is arguably the most successful international treaty to date. The Montreal Protocol is an international protocol to the Vienna Convention, agreed in before entering into force in Its purpose was to phase-out reduce and eventually eliminate the use of man-made ozone-depleting substances for protection of the ozone layer.

The Protocol has now reached universal ratification, with South Sudan as the final signatory in Since its first draft in , the Montreal Protocol has undergone numerous amendments of increasing ambition and reduction targets.

In the chart we see various projections of historic and future concentrations of effective chlorine substances i. These are mapped from assumptions of no international protocol, the first Montreal treaty in , followed by subsequent revisions of increasing ambition. However, even under the initial Montreal Protocol, and subsequent London amendment, reduction controls and targets would have been too relaxed to have resulted in a reduction in ODS emissions.

However, the Copenhagen and its subsequent revisions greatly increased controls and ambition in global commitments, leading to a peak in stratospheric concentrations in the early s and projected declines in the decades to follow.

In the chart we see average stratospheric ozone concentrations in the Southern Hemisphere where ozone depletion has been most severe from to Ozone concentrations are measured in Dobson Units DU : this is number of molecules of ozone that would be required to create a layer of pure ozone 0. For several decades since the s, concentrations have continued to approximate around or below DU. Over the last few years since , however, ozone concentrations have started to slowly recover.

Has the fall of stratospheric ozone concentrations been reflected in an ozone hole? In the chart we see the maximum and mean ozone hole area over Antarctica, measured in square kilometres km 2. Like gas concentrations, ozone hole area is monitored daily by NASA via satellite instruments. Since we see a distinct increase in the Antarctic ozone hole area, reaching a maximum of 30 million km 2 in the early s. However, since the late s, the ozone hole area had approximately stabilised between 20 to 25 million km 2.

Full recovery is, however, expected to take until at least the second half is this century as described in the entry below. The Ozone Layer has recently shown early signs of recovery. However, full recovery of stratospheric ozone concentrations to historical levels is projected to take many more decades.

In the charts we profile historic levels and future projections of recovery in two forms: equivalent stratospheric chlorine i. ODS concentrations, and stratospheric ozone concentrations through to This is measured as the global average, as well as concentrations Antarctic and Artic zones. Note that such projections are given as the median lines from a range of chemistry-climate; true modelled results presented in the Montreal Protocol Scientific Assessment Panel report present the full range of modelled estimates, with notable confidence intervals.

The data presented is measured relative to concentrations in where is equal to 0. ODS can have a significant lifetime in the atmosphere, for some between 50 and years on average. This means that despite reductions in ODS emissions and eventually complete phase-out of these substances , equivalent stratospheric chlorine ESC concentrations are expected to remain higher than levels through to the end of the century.

Antarctica, where ozone depletion has been most severe due to very low temperatures is expected to recover much more slowly. The story of international cooperation and action on addressing ozone depletion is a positive one: the Vienna Convention was the first Convention to receive universal ratification. Over the last few decades we have seen a dramatic decline in emissions of ozone-depleting substances. Montzka et al. Atmospheric concentrations of CFC have been measured and tracked back to the s via air collection and analysis with automated onsite instrumentation, such as with gas chromatography coupled with electron capture detection GC—ECD.

This allows us to track atmospheric concentrations over time. Using statistics on reported emissions of CFC submitted by parties to the Montreal Protocol, it is possible to construct estimates and projections of what change in atmospheric concentration should occur based on such levels of emissions.

In the chart we see the annual change in percent of measured concentrations of CFC shown as the solid line. As we see, actual and expected concentration changes map closely over the period up to Since , however, the annual rate of decline in concentrations has fallen almost halved from This is highly inconsistent with the expected rate of change which would have resulted in the case that reported emissions to the Montreal Protocol were correct.

This inconsistency between actual and expected rate of change particularly in the case of a slowdown in concentration decline suggests an increase in global emissions despite reports close to zero since 8. However, some additional measurements allowed the authors to provide an informed estimate. Using combined CFC measurements in the Northern and Southern Hemisphere and atmospheric transport models, the authors suggested the likely source of additional CFC emissions was from the Northern Hemisphere.

Share sensitive information only on official, secure websites. JavaScript appears to be disabled on this computer. Please click here to see any active alerts. The Earth's ozone layer ozone layer The region of the stratosphere containing the bulk of atmospheric ozone. The ozone layer lies approximately kilometers miles above the Earth's surface, in the stratosphere. Depletion of this layer by ozone depleting substances ODS will lead to higher UVB levels, which in turn will cause increased skin cancers and cataracts and potential damage to some marine organisms, plants, and plastics.

Less ozone-layer protection from ultraviolet UV light ultraviolet UV light Ultraviolet radiation is a portion of the electromagnetic spectrum with wavelengths shorter than visible light. UVA is not absorbed by ozone. UVB is mostly absorbed by ozone, although some reaches the Earth. UVC is completely absorbed by ozone and normal oxygen.

Scientific Assessment of Ozone Depletion: The Earth's atmosphere is composed of several layers. The lowest layer, the troposphere troposphere The region of the atmosphere closest to the Earth.

The troposphere extends from the surface up to about 10 km in altitude, although this height varies with latitude. Almost all weather takes place in the troposphere. Everest, the highest mountain on Earth, is only 8.

Temperatures decrease with altitude in the troposphere. As warm air rises, it cools, falling back to Earth. This process, known as convection, means there are huge air movements that mix the troposphere very efficiently. Virtually all human activities occur in the troposphere.

Everest, the tallest mountain on the planet, is only about 5. The next layer, the stratosphere stratosphere The region of the atmosphere above the troposphere.

The stratosphere extends from about 10km to about 50km in altitude. Commercial airlines fly in the lower stratosphere. The stratosphere gets warmer at higher altitudes. In fact, this warming is caused by ozone absorbing ultraviolet radiation.

Warm air remains in the upper stratosphere, and cool air remains lower, so there is much less vertical mixing in this region than in the troposphere. Most commercial airplanes fly in the lower part of the stratosphere. Health and Environmental Effects of Ozone Depletion. Ozone Layer Research and Technical Resources. Information for students about the Ozone Layer. Addressing Ozone Layer Depletion. Adapting to a Changed Ozone Layer. Phasing Out Ozone-Depleting Substances. Managing Refrigerant Emissions.

Most atmospheric ozone is concentrated in a layer in the stratosphere, about 9 to 18 miles 15 to 30 km above the Earth's surface see the figure below. Ozone is a molecule that contains three oxygen atoms. Go Further.

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