Accueil » Couche d'ozone » Niveau 2

L'évolution de l'appauvrissement de la couche d'ozone, son impact sur le changement climatique, la santé et l'environnement.


    The Assessment reports on key findings on environment and health since the last full Assessment of 2010, paying attention to the interactions between ozone depletion and climate change.

    The most severe and most surprising ozone loss was discovered to be recurring in springtime over Antarctica. The loss in this region is commonly called the “ozone hole” because the ozone depletion is so large and localized. In response to the prospect of increasing ozone depletion, the governments of the world crafted the 1987 United Nations Montreal Protocol as an international means to address this global issue. Thanks to development of “ozone-friendly” substitutes for the now-controlled “Ozone Depleting Substances” (ODS) substances, such as chloro-fluoro-carbons or CFCs long used a.o. in most refrigeration and air conditioning systems, the total global accumulation of ODS has slowed and begun to decrease and initial signs of recovery of the ozone layer have been identified. Production and consumption of all principal ODS by developed and developing nations has already been largely decreased and will be almost completely phased out before the middle of the 21st century.

    Those gases that are still increasing in the atmosphere, such as halon-1301 and HCFCs, will begin to decrease in the coming decades if compliance with the Protocol continues. However, it is only after mid-century that the effective abundance of ODS is expected to fall to values that were present before the Antarctic ozone hole was first observed in the early 1980s.

    According to the UNEP progress report (2015)1, by 2013 the implementation of the Montreal Protocol had already achieved significant benefits for the ozone layer and, consequently, for surface UV-B radiation. Model calculations have shown that, without the Montreal Protocol, a deep Arctic “ozone hole”, would have occurred in 2011 given the meteorological conditions in that year. The decline of stratospheric ozone over the Northern Hemisphere mid-latitudes would have continued, more than doubling to about 15% by 2013 relative to the onset of ozone-depletion. In addition, the Antarctic ozone hole would have been 40% larger in 2013 relative to what was observed, with enhanced loss of ozone also at sub-polar latitudes of the Southern Hemisphere.

    1 UNITED NATIONS ENVIRONMENT PROGRAMME Environmental Effects of Ozone Depletion and its Interactions with Climate Change Progress Report, 2015

    What is stratospheric ozone and how is it formed?

      Ozone is constituted of three atom of oxygen combined which is formed in upper part of the Earth’s atmosphere in small amounts where it forms a layer. This layer is vital to human well-being and ecosystem health as it absorbs a large part of the Sun’s biologically harmful ultraviolet radiation.. This region, called the stratosphere, is more than 10 km (6 miles) above Earth’s surface. There, about 90% of atmospheric ozone is contained in the “ozone layer,” which shields us from harmful ultraviolet radiation from the Sun. In the mid-1970s, it was discovered that some human-produced chemicals could lead to depletion of the ozone layer.

      By contrast, ozone formed at Earth’s surface in excess of natural amounts is considered “bad” ozone because it is harmful to humans, plants, and animals but ozone produced naturally near the surface and in the lower atmosphere plays an important beneficial role in chemically removing pollutants from the atmosphere.

      The distribution of total ozone over Earth varies with location on timescales that range from daily to seasonal. Total ozone is generally lowest at the equator where it is produced and highest in polar region atmosphere. The variations are caused by large-scale movements of stratospheric air and the chemical production and destruction of ozone. An important feature of seasonal ozone changes is the natural chemical destruction that occurs when daylight is continuous in the summer polar stratosphere, which causes total ozone to decrease gradually toward its lowest values in early fall.

      How is stratospheric ozone depleted?

        The initial step in the depletion of stratospheric ozone induced by human activities is the emission, at Earth’s surface, of certain organic gases containing chlorine and bromine like the CFCs used in part because their low reactivity and toxicity along with carbon tetrachloride (CCl4) and methyl chloroform (CH3CCl3) and the halons, which were used in fire extinguishers. Halogen source gases are compared in their effectiveness to destroy stratospheric ozone using their Ozone Depletion Potential (ODP) calculated relative to CFC-11, which has an ODP defined to be 1. A gas with a larger ODP destroys more ozone over its atmospheric lifetime. Lifetimes of the principal zone-depleting substances vary from 1 to 100 years.

        Because they are unreactive and do not dissolve readily in rain or snow, these gases accumulate in the lower atmosphere. Natural air motions transport these accumulated gases to the stratosphere, where they are converted to more reactive molecules by the ultraviolet radiation originating from the sun. Some of these molecules, like chlorine radicals and chlorine monoxide (ClO) then participate in reactions that destroy ozone in “catalytic” cycles made up of two or more separate reactions. As a result, a single chlorine or bromine atom can destroy many thousands of ozone molecules before it leaves the stratosphere and returns to the lower atmosphere where these reactive chlorine and bromine gases are removed from Earth’s atmosphere by rain and snow.

        The severe depletion of the Antarctic ozone layer known as the “ozone hole” occurs because of the special meteorological and chemical conditions that exist there when the very low winter temperatures in the Antarctic stratosphere cause polar stratospheric clouds (PSCs) to form which are isolated from stratospheric air in the polar vortex and preventing “fresh ozone” from the tropical region to temporarily replace the destroyed ozone, thus producing the ozone hole in Antarctic springtime. Depletion of the global ozone layer increased gradually in the 1980s and reached a maximum of about 5% in the early 1990s. The depletion has lessened since then and now is about 3% averaged over the globe.

        Significant depletion of the Arctic ozone layer also occurs in most years in the late winter/early spring period (January–March). However, the maximum depletion is less severe than that observed in the Antarctic and with large year-to-year differences as a consequence of the highly variable meteorological conditions found in the Arctic polar stratosphere.

        Eventually other factors such as changes in solar radiation, as well as the formation of stratospheric particles after volcanic eruptions, also influence and may affect the ozone layer.

        Was the Montreal protocol signed in 1985 effective to protect and restore the ozone layer?

          Maximum ozone hole area
          Maximum ozone hole area
          Source: European Environmental Agency

          The Montreal Protocol controls led to a substantial reduction in the emissions of ODS over the last two decades. The Scientific Assessment Panel of the Montreal Protocol on Substances that Deplete the Ozone Layer2 concludes that atmospheric abundance of most controlled ODS is decreasing. There are several indications that the global ozone layer is beginning to recover from ODS-induced depletion.

          Observations now show a clear 5% increase of ozone in the upper stratosphere (42 km) over the 2000-2013 period. Model simulations suggest that about half of this increase results from a cooling in this region due to CO2 increases, while the other half results from Equivalent Effective Stratospheric Chlorine (EESC), designed as one measure of the potential for ozone depletion in the stratosphere, decreases. However, the variability of the atmosphere and the influence of climate change have hindered a definitive attribution of the observed global ozone increases since 2000 to the concomitant ODS decreases.

          In Antarctica, large ozone depletion continues to occur each year. In the Arctic, ozone depletion is generally less pronounced than in Antarctica but more variable: the very high stratospheric ozone concentrations observed in the spring of 2010 were followed by record-low concentrations in spring 2011.

          These reductions of emissions of ODS, while protecting the ozone layer, have the additional and very significant benefit of reducing the human contribution to climate change. Without Montreal Protocol controls, the contribution to climate forcing from annual ODS emissions could now be 10-fold larger than its present value, which would be a significant fraction of the climate forcing from current carbon dioxide (CO2) emissions3 . Increases in ODS substitute gases, which are also greenhouse gases but to a lesser extent, could offset much of this climate benefit by substantially contributing to human induced climate forcing in the coming decades.

          3 The ozone depleting halocarbons which are now banned contribute indeed to a radiative forcing which is 14% of the radiative forcing from all of the globally mixed greenhouse gases. Technical Summary page 42 - A report accepted by the Working Group I of the IPCC but not approved in detail

          What about the increase of UV-B irradiance associated to the ozone layer depletion?

            As a result of the success of the Montreal Protocol in limiting ozone depletion, since the mid-1990s the changes in UV-B measured at many sites are due largely to factors other than ozone. Nevertheless stabilisation of the concentrations of stratospheric ozone and possible beginning of a recovery of UV-B irradiance are not yet detectable in the measurements because of the large natural variability.

            In the meantime, the increases in UV-B irradiance, ranging from 5 to 10% per decade and reported for several northern mid-latitude sites, are caused predominantly by reductions in cloudiness and aerosols while UV-B irradiance decrease at some northern high latitude sites, during that period, are mainly due to reduction in snow- or ice-cover. Future levels of UV-B irradiance at high latitudes will be determined by the recovery of stratospheric ozone and by changes in clouds and reflectivity of the Earth’s surface. In Antarctica, reductions of up to 40% in mean noontime UV Index (UVI) are projected for 2100.

            According to the progress report 2015, measurements at several sites over the last decade have shown decreases in surface UV-B radiation that are consistent with observed increases in total ozone. However, at some sites, changes in aerosols, clouds and, at high latitudes, sea ice were the main drivers of changes in UV-B radiation.

            The UVI is indeed, according to the UNEP report, projected to decrease by up to 7% at northern high latitudes because of the anticipated increases in cloud cover and reductions in surface reflectivity due to ice-melt while anticipated decreases in aerosols would result in increases in the UVI, particularly in densely populated areas. Outside the Polar regions, future changes in UV-B irradiance will likely be dominated by changes in factors other than ozone and by the end of the 21st century, the effect of the recovery of ozone on UV-B irradiance will be very small, leading to decreases in UVI of between 0 and 5%.

            The 2015 report states that from a variety of proxy data for nine locations in Spain, erythremal irradiance increased between 1950 and 2011 by about 13%, of which half was due to decreases in ozone while between 1985 and 2011, an increase of about 6% was calculated, mostly due to decreasing amounts of aerosols and clouds.

            In the Arctic, the areal extent and thickness of sea ice continue to decline. Recent modelling efforts estimate that exposure to the UV-B wavelength range in the surface waters of the Arctic Sea may increase as much as tenfold between 1950 and 2100 due to the melting of sea ice.

            What is the link between the ozone layer depletion and climate change?

              Ozone depletion itself is not the principal cause of global climate change. Changes in ozone and climate are directly linked because ozone absorbs solar radiation and is also a greenhouse gas. Stratospheric ozone depletion leads to surface cooling, while the observed increases in tropospheric ozone and other greenhouse gases lead to surface warming.

              The ozone layer depletion also helped to keep East Antarctica cold, but conversely has helped to make the Maritime Antarctic region one of the fastest warming regions on the planet. In contrast to the warming of most ocean waters, there is a significant cooling in the North Atlantic between Greenland and Ireland. This is due to a weakening of the Gulf Stream that heats the North Atlantic, the American East coast, and Northern Europe.

              For the 2015 report, when considering the effects of climate change, it has become clear that processes resulting in changes in stratospheric ozone are more complex than previously believed. As a result of this, human health and environmental problems will be longer-lasting and more regionally variable.

              The solar UV radiation has the potential to contribute to climate change via its stimulation of emissions of carbon monoxide, carbon dioxide, methane, and other volatile organic compounds from plants, plant litter and soil surfaces but their magnitude, rates and spatial patterns remain highly uncertain at present.

              These UV radiation processes could also increase emissions of trace gases that affect the atmospheric radiation budget (radiative forcing) and hence changes in climate.

              Resultant changes in precipitation patterns have been correlated with ecosystem changes such as increased tree growth in Eastern New Zealand and expansion of agriculture in South-eastern South America. Conversely, in Patagonia and East Antarctica, declining tree and moss bed growth have been linked to reduced availability of water. A full understanding of the effects of ozone depletion on terrestrial ecosystems in these regions should therefore consider both UV radiation and climate change.

              Solar UV radiation is driving production of substantial amounts of carbon dioxide from Arctic waters. The production is enhanced by the changes in rainfall, melting of ice, snow and the permafrost, which lead to more organic material being washed from the land in to Arctic rivers, lakes and coastal oceans. Solar UV radiation degrades this organic material, which stimulates CO2 and CO emissions from the water bodies, both directly and by enhanced microbial decomposition. New results indicate that up to 40% of the emissions of CO2 from the Arctic may come from this source, much larger than earlier estimates.

              Where photochemical priming plays an important role, changes in continental runoff and ice melting, due to climate change, are likely to result in enhanced UV-induced and microbial degradation of dissolved organic matter and release of carbon dioxide (CO2). Such positive feedbacks are particularly pronounced in the Arctic resulting in Arctic amplification of the release of CO2 (see next point).

              Other changes in climate associated with ozone layer depletion include changes to wind patterns, temperature and precipitation across the Southern Hemisphere. More intense winds lead to enhanced wind-driven upwelling of carbon-rich deep water and less uptake of atmospheric CO2 by the Southern Ocean, reducing the oceans potential to act as a carbon sink (less sequestering of carbon). These winds also transport more dust from drying areas of South America into the oceans and onto the Antarctic continent. In the oceans this can enhance iron fertilisation resulting in more plankton and increased numbers of krill. On the continent the dust may contain spores of novel microbes that increase the risk of invasion of non-indigenous species and this transport from drying areas, such as in South America, into the oceans, may enhance fertilisation by iron and resulting in more plankton and greater carbon uptake.

              Conversely, says the 2015 report, climate change could enhance the production in marine environments of short-lived halogens (e.g., methylene chloride, bromoform) that cause depletion of ozone in the stratosphere and troposphere.

              What is the link between ozone depletion gases (ODS) and climate change?

                Most ozone depleting substances are also strong greenhouse gases and, in a world without the Montreal Protocol on ODS ban (minus 98% consumption worldwide between 1986 and 2015) restrictions, annual ODS emissions could be today as important for climate forcing as those of CO2 and be 10-fold larger than its present value4. Transitory ODS substitute gases, H-CFCs first, then HFCs (hydrofluorocarbons) are also greenhouse gases but most of them to a lesser extent and their transitory use as substitutes to ODS represented the most important contribution to the reduction of the global greenhouse gases emissions.

                Anyway, because the first generations of substitute chemicals, like hydrofluorocarbons (F-gases or HFCs) had still a significant greenhouse gas potential which could in the long term offset the climate benefit by substantially contributing to human induced climate forcing, their progressive phasing out was decided in 2016 in an amendment of the Montreal Protocol5.

                Other changes in climate associated with ozone layer depletion include changes to wind patterns, temperature and precipitation across the Southern Hemisphere reducing the oceans potential to act as a carbon sink (less sequestering of carbon).

                4 The importance of the Montreal Protocol in protecting climate. G. J. M. Velders et al. Netherlands Environmental Assessment Agency; .S. EPA, Earth System Research Laboratory; National Oceanic and Atmospheric Administration, and DuPont Fluoroproducts. PNAS vol. 104 -12, 4814–4819, 2007.

                Has ozone depletion produced significant effects on human health?

                  In spring 2011 the erythemal (sunburning) dose averaged over the duration of the low-ozone period increased by 40-50% at several Arctic and Scandinavian sites in response to episodic decreases of ozone at high latitudes (about 25% over Central Europe). Nevertheless, according to the UNEP report (2014), changing behaviour with regard to sun exposure by many fair-skinned populations has probably had more significant adverse and beneficial consequences on human health than increasing UV-B irradiance due to ozone depletion. The increase in holiday travel to sunny climates, wearing clothing that covers less of the body, and the desire for a tan are all likely to have contributed to higher personal levels of exposure to UV-B radiation than in previous decades.

                  Regarding adverse effects:

                  • Immediate adverse effects of excessive UV-B irradiation are sunburn of the skin and inflammation of the eye including photo-conjunctivitis or photo-keratitis, cancers of the eyelid and the surface of the eye, cortical cataract and pterygium.
                  • Long-term regular low dose or repeated high-dose exposure to the sun causes melanoma and non-melanoma (basal and squamous cell) carcinomas of the skin and cataract and pterygium (a growth on the conjunctiva) of the eye.

                  The incidence of each of these skin cancers has risen significantly since the 1960s in fair-skinned populations, but has stabilised in recent years in younger age groups in several countries, perhaps due to effective public health campaigns. Cataract is the leading cause of blindness worldwide. The 2015 report underlines that incidence of both non-melanoma skin cancers, primarily in fair-skinned populations, and cutaneous melanoma (CM) continues to increase globally with exposure to solar UV radiation the most important cause but, in many countries, mortality may have peaked. For example, the age-standardised incidence rate of CM per 100,000 persons in the UK for 2009-2011 increased by 57% in men and 39% in women respectively, compared to 2000-2002 and doubled from 1982 to 2011 in the USA.

                  Exposure to solar UV radiation can also alter the immune response to a variety of microorganisms in animal studies, and recent reports support a similar role in humans.

                  Common strategies to avoid over-exposure to solar UV radiation should aim to balance the harmful and beneficial effects of sun exposure even if such a balance may be difficult to achieve in practice as the recommended time outdoors will differ between individuals, depending on personal factors such as skin colour, age, and clothing as well as on environmental factors such as location, time of day, and season of year.

                  Regarding beneficial effects of exposure of the skin to solar UV radiation the major known is the synthesis of vitamin D with is critical in maintaining blood calcium levels and is required for strong bones and its deficiency might increase the risk of an array of diseases such as cancers, autoimmune diseases and infections.

                  What are the impacts of ozone layer depletion and UV-B increases on terrestrial ecosystems?

                    Various abiotic and biotic factors affect plants are influenced by UV-B radiation in ways that can have both positive and negative consequences on plant productivity and functioning of ecosystem in intricate feedbacks and complexity. Plant productivity is likely decreased slightly due to the increased UV radiation while exposure to UV-B radiation can promote plant hardiness, and enhance plant resistance to herbivores and pathogens, improving the quality, and increase or decrease the yields of agricultural and horticultural products.

                    While UV-B radiation does not penetrate into soil to any significant depth, it can affect a number of belowground processes through alterations in aboveground plant parts, microorganisms, and plant litter. These include modifications of the interactions between plant roots, microbes, soil animals and neighbouring plants, with potential consequences for soil fertility, carbon storage, plant productivity and species composition. UV-B radiation can also influence rates of photodecomposition of dead plant and is now being considered as an important driver of decomposition, although uncertainty exists in quantifying its significance. It is known that UV radiation facilitates the breakdown of pesticides and may in some cases increase toxicity of certain pesticides and/or their degradation products.

                    The 2015 report also underlines that stimulation by UV radiation of polyphenolics can increase the nutritional quality of plant products and plant tolerance to stress conditions and that the increased frequency and extent of wildfires due to climate change become important sources of aerosols which emit black carbon (BC) and organic carbon (OC) smoke particles that can persist in the atmosphere for days to weeks with significant effects on surface UV radiation.

                    What are the impacts of ozone layer depletion on aquatic ecosystems?

                      Species composition and distribution of many marine ecosystems may strongly be influenced with warmer oceans due to feedbacks between temperature, UV radiation and greenhouse gas concentrations.

                      Higher air temperatures are increasing the surface water temperatures of numerous lakes and oceans, with many large lakes warming at twice the rate of air temperatures in some regions. Warming of the ocean results in stronger stratification that decreases the depth of the upper mixed layer and also reduces upward transport of nutrients across the thermocline from deeper layers. The decrease in the depth of the upper mixed layer exposes organisms that dwell in it to greater amounts of solar visible and UV radiation which may overwhelm their capability for protection and repair by producing UV-absorbing compounds. On the other hand, climate change-induced increases in concentrations of dissolved organic matter in inland and coastal waters reduce the depth of penetration of UV radiation.

                      Increased concentrations of atmospheric CO2 are continuing to cause acidification of the ocean, which also alters marine chemical environments and interferes with the calcification process by which organisms, such as phytoplankton, macroalgae and many animals including molluscs, zooplankton and corals, produce exoskeletons protecting themselves from predators and solar UV radiation.

                      Phytoplankton (primary feed producers) are decreasing along the West side of the Antarctic Peninsula due to increased solar UV-B radiation and rapid regional climate change. For others such as corals, the warming may alter their tolerance of other stressors. This warming also can shift the thermal niche of organisms towards the pole and causes changes in community structure. Change in ice phenology as well as light and nutrient availability may affect species composition.

                      Decreased penetration of UV radiation also reduces the natural disinfection of surface water containing viruses, pathogens, and parasites. In contrast to the UV-disinfection of surface waters, exposure to high levels of UV radiation can either stress or suppress the immune system of hosts, making them more susceptible to infection.

                      Eventually, microplastics debris created in the oceans by solar UV radiation from the weathering of plastic litter on beaches is also a growing environmental issue. These microplastic particles concentrate toxic chemicals dissolved in seawater and are ingested by zooplankton, thus providing a potential mechanism for transfer of pollutants into the marine food web.

                      Are there other environmental effects of ozone layer depletion?

                        The carbon cycle is strongly influenced by interactions between droughts and intensity of UV-radiation at the Earth’s surface. Increased aridity due to climate change and severity of droughts will change the amount of plant cover, thereby increasing UV-induced decomposition of dead plant matter (plant litter). These increased losses could have large impacts on terrestrial carbon cycling in arid ecosystems.

                        New results have shown that lignin is readily decomposed with exposure to solar UV radiation, reducing long-term storage of carbon in perennial terrestrial systems.

                        UV radiation also induces photoreactions that dissipate pollutants and pathogens says the 2015 report, which affect the fate and transport of pesticides, pharmaceuticals, heavy metals, nanomaterials and pathogens.

                        Is ozone layer depletion affecting air quality?

                          UV radiation is known to be a critical driver of the formation of photochemical smog, e.g. ozone and aerosols. UV radiation may also play a role in the destruction of aerosol particles. Ground-level ozone concentrations may increase substantially over large geographic regions due to a combination of stratospheric ozone recovery and climate change in the coming decades. UV radiation is an essential driver for the formation of photochemical smog, which consists mainly of ground-level ozone and particulate matter. Greater exposures to these pollutants have been linked to increased risks of cardiovascular and respiratory diseases in humans and are associated globally with several million premature deaths per year. Tropospheric (ground-level) ozone may alter biological diversity and affect the function of natural ecosystems and also have adverse effects on yields of crops. Future changes in UV radiation and climate and significant reductions in emissions will alter the rates of formation of ground-level ozone and some particulate matter and must be considered in predictions of air quality and consequences for human and environmental health.

                          Hydroxyl radicals (∙OH), which are responsible for the self-cleaning of the atmosphere UV radiation, are also affected by changes in UV radiation. However, on global scales, models differ in their predictions with consequent uncertainties.

                          By contrast, based on current data says the 2015 report, the amount of trifluoroacetic acid (TFA) formed from HCFCs and HFCs in the troposphere is too small to be a risk to the health of humans and the environment. No new negative environmental effects of the substitutes for the ozone depleting substances or their breakdown-products have been identified even if some present substitutes for the ozone depleting substances continue to contribute, although much less than former ozone depleting substances like CFCs, to global climate change if concentrations rise above current levels.

                          Has the increase of UV-radiation an impact on materials resistance?

                            Solar UV radiation and climate change affect the outdoor service lifetime of PVC building products, still the most-used plastic in building and of polypropylenes containing recycled plastic by changes in bulk morphology that also results in a reduced. Nanoscale inorganic fillers could provide superior stability against solar UV irradiation relative to conventional fillers in coatings especially those in clear-coatings on wood or textile fibre-coatings of textile and plastics. The benefits of nanofillers in bulk plastics, however need more information to assess their efficacy.

                            Regarding wood, graphene, zirconium dioxide, iron oxide, titanium, and cerium oxide can control UV-induced yellowing in several wood species. Similarly, surface modification of wood with nanocellulose crystals and epoxidised soybean oil also result in good UV stabilisation.

                            Effectiveness of specific fabrics depends on the weave characteristics but can be further improved by surface-treating the fibres with a UV absorber. Textile fabrics block the personal exposure to solar UV radiation, whereas glass usually blocks mainly UV-B radiation. Glazing for windows is being developed to further improve their thermal properties and also results in increased filtering of the UV radiation with benefits for health of humans and indoor components of buildings and artwork. In cable-jackets with the new aluminum-based fire retardants, initial degradation by UV radiation yields a filler-rich surface layer that screens the underlying polymer from further degradation.

                            What was the situation of ozone-depleting substances in the European Union market in 2015?

                              The European Environmental Agency (EEA) publishes a yearly report on the subject 6,7. Globally, consumption of ODS controlled under the Montreal Protocol declined by some 98.34 % worldwide between 1986 and 2015.

                              However, much remains to be done to ensure that the damage to the ozone layer is reverted. Initiatives to further reduce releases of ODS could involve the following:

                              • Addressing the strong growth in the production and consumption of HCFCs in developing countries;
                              • Collecting and safely disposing of the large quantities of ODS contained in old equipment and buildings (the so-called ODS 'banks');
                              • Ensuring that restrictions on ODS continue to be properly implemented and the remaining worldwide use of ODS declines further;
                              • Preventing illegal trade in ODS; and
                              • Strengthening the international and European framework on ODS (e.g. inclusion of other known ODS, restricting exemptions).

                              Consumption: The consumption of ODS in the EU has been negative or close to zero since 2010 and, in 2015, the consumption of controlled substances reached its lowest negative level since 2006 . Controlled substances with a high ODP (e.g. CFCs and CTC) exhibit a different trend in consumption from those with a low ODP (e.g. HCFCs).

                              Imports: The largest imported quantities were of hydrochlorofluorocarbons (HCFCs) (52 % when expressed in metric tonnes), methyl bromide (MB), chlorofluorocarbons (CFCs) and bromochloromethane (BCM) and virgin carbon tetrachloride (CTC) and virgin CFCs when expressed in ODP tonnes.

                              Exports: The quantity of controlled virgin substances exported from the EU (including re-export) continued to decline (down by 17 %), and the total quantity exported in 2015 (2 152 ODP tonnes) was made up predominantly of HCFCs (84 % when expressed in metric tonnes), 26 % lower than that in 2014.

                              Production: Controlled substances produced were predominantly HCFCs (71 % of the total production in metric tonnes), CTC and trichloroethane (TCA) down by 4 %. Controlled substances were produced almost exclusively for feedstock use inside the EU (91 % of the quantity produced, in metric tonnes) with a decline in production for some uses, e.g. refrigeration, unintentional by-production, process agent use and feedstock use outside the EU.

                              Only minor quantities of CFCs and hydrobromofluorocarbons (HBFCs), and no MB or BCM, were produced in 2015. A total of about 10 000 tonnes of controlled substances (CTC, HCFCs and CFCs) were destroyed, explained to a large extent by the increased destruction, compared with 2014, of unintentionally produced CTC.

                              The production of new substances (expressed in metric tonnes) was six times higher than the production of controlled substances. However, owing to the lower ODP of new substances, these amounts constitute, when expressed in ODP tonnes, approximately 30 % of the combined production of controlled and new substances in the EU.

                              Emissions: The total make-up and emissions of controlled substances used as process agents stayed well below restrictions imposed by both the Montreal Protocol and the ODS Regulation. Emissions of controlled substances from their use as feedstock decreased to an average emissions rate of 0.07 % (calculated as the ratio of total emissions to total quantities used as make-up (4), expressed in metric tonnes).

                              F-gases: Approximately 75 % (both in tonnes and CO2 eq.) of F-gases supplied to the market in 2015 were intended for use as refrigerants for refrigeration, air conditioning and heating purposes. These were almost exclusively HFCs.

                              • Of 2015 total supply, 10 % (by mass) was intended for use in insulation foams; 96 % of this was HFCs. Measured in CO2 eq., the proportion of F-gases intended for use in foams was only 3 %.
                              • Aerosols (both medical and non-medical) were the intended application of 10 % (tonnes) of 2014 total supply, 6 % as CO2 eq. The gases used for aerosols were almost entirely HFCs.
                              • SF6 intended for electrical equipment (switchgear) contributed only a small fraction when measured in tonnes but a considerable portion of supply as CO2 eq.

                              The overall trends that can be identified from companies reporting can be summarised as follows:

                              • Production of F-gas continued to decline, with 2015 levels 5 % (as CO2 eq.) below those reported for 2014;
                              • Imports decreased by about 40 % compared with the exceptionally high amounts reported for 2014 (by weight and as CO2 eq.). Compared with 2013, bulk imports in 2015 increased by about 8 % ;
                              • Exports have decreased by 2 % (tonnes) or 1 % (CO2 eq.) since 2014. Compared with 2013, exports in 2015 increased by 18 % (tonnes) and 23 % (CO2 eq.).
                              • Supply has decreased by about 24 % (by weight and as CO2 eq.) since 2014. Compared with 2013, bulk supply (7) increased by 9 % by weight but decreased by 3 % as CO2 eq. in 2015.

                              Destruction of F-gases has been increasing consistently since 2008, with the exception of very low numbers reported for 2013. While destroyed gases are not accounted for in the bulk supply/total supply metrics, if compared with bulk supply, the 2015 level of destruction would be 1.5 % of bulk supply by mass or 5 % as CO2 eq.


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