III. Stratospheric Ozone Depletion Boundary: Average conc. of stratospheric O3 no lower than 276 Dobson units Current level: 283 Dobson units Diagnosis: Safe, and improving History of Ozone Depletion Research 1974 - 1 atom of chlorine can decompose circa 100 000 O3 molecules! 1978 - CFC (chloro-fluoro-carbons) banned in sprays in USA - CFC consumption in other applications, however, still grows 1991 1984 - Halley Bay station in Antartica measured 40 % O3 decrease - the same dramatic decrease verified in another station 1000 miles away 1987 - chlorine-ozone hypothesis confirmed by the fly of a exploratory plane through the ozone hole measuring concentration of O3 and ClO - there was found strong negative correlation between the concentration of both determined compounds Significance of the Ozone Depletion O3 – protection of biosphere against harmful UVB radiation Degradation of O3 layer - Cl radicals from Chloro-fluoro-carbons (CFC, Freon) - Br radicals from Bromo-fluoro-carbons (BFC, Halons) Degradation of O3 layer - Cl∙ radicals from Chloro-fluoro-carbons (CFC, Freon) - Br∙ radicals from Bromo-fluoro-carbons (BFC, Halon) Ozone hole - ozone depletion primarily over the South pole area - however, significant O3 depletion observed everywhere Consequences of O3 depletion Less O3 = more cancer 1% ↓ conc. O3 ≈ 2% ↑ intensity UVB ≈ 4% ↑ skin cancer hazard - majority of melanoms are on sunlit parts of the skin - greatest incidence in Australia Impact of increased UVB irradiaton on crop Ozone hole - solution Effect of accepted solutions 1985 – Vienna Convention for the Protection of the Ozone Layer 1987 – Montreal protocol + amendments Time delay – ozone depletion and recovery Řešení a důsledky 1985 – Vienna Convention for the Protection of the Ozone Layer 1987 – Montreal protocol + amendments „for their work in atmospheric chemistry, particularly concerning the formation and decomposition of ozone.“ Effect of accepted solutions 1985 – Vienna Convention for the Protection of the Ozone Layer 1987 – Montreal protocol + amendments Costs of CFC abandonment - 1988-2000 – product. decreased for 90% - overal costs of abandonment - 40 bil. $ - no job losses - 1/3 simply not necessary - new HFC in cars increased car price for 50-150 $ (prognosed 1000-1500 $) - CH3Br for soil sterilisation replaced e.g. with crop rotation - CH3Br for stores fumigation replaced with CO2 A common but differentiated responsibility Lesson from successful solution of global issue - cooperation of all the following stakeholders: • scientific discoveries and monitoring – problem notification • UNEP – international coordinator of legal measures • environemntal activists – pressure to solve the issue • responsible consuments – purchasing according to env. info • technical experts - developing env.-friendly alternatives • flexible and responsible industry IV. Ocean acidification Ocean acidification - what is the cause? Change in pH of oceans 1700-2000 Change in pH of oceans - 3D distribution „Natural laboratory“ V and VI. Biogeochemical flows of P and N N - Nitrogen – natural geochemical cycle N - Nitrogen N - Nitrogen - today, human activity changes more N2 to reactive forms of N than all terestrial processes together - Haber-Bosch 80 MtN/yr, leguminosis 40 MtN/yr, fossil fuels combustion 20 MtN/yr, biomass combustion10 MtN/yr - major reason of N2 fixation ? N - Nitrogen N - Nitrogen - major reason of N2 fixation ? - N-fertilizers - significant part ends in water – eutrofication and nitrates issue - significant part ends in atmosphere N2O is GHG and O3 decomp. - owerall decrease of resilience of planetary systems thanks to high input of reactive nitrogen molecules P – phosphorus – natural geochemical cycle HumaninterventiontoPcycle P - phosphorus - primary source - weathering or apatite mining - anthropogenic flow to oceans - 8-9x higher amount - from 20 MtN/yr industr. P – half ends in oceans - higher risk of anoxic events Consequences of guano mining - Nauru P + N = anoxic zones in oceans P + N = anoxic zones in oceans Not clear everything on anoxic zones... Not clear everything on anoxic zones... and phosphate cascade VII. Global freshwater consumption Boundary: No more than 4000 km3 of fresh water consumed per year Current level: 2600 km3 per year Diagnosis: Boundary will be approached by mid-century FW issue - man is a dominant force changing flow of water in rivers - cca 25 % water not reach the ocean - consequences for biodiversity, nutrition, aquatic and terestrail ecosystems Aral See - Kazachstan, Uzbekistan - 2005 – dam betwee N and South part - what happened? - 2005 – dam betwee N and South part - what happened? Lake Hamoun – Iran, Afghanistan Areas of water consumption Areas and types of water scarcity VIII. Land use Santa Cruz, Bolívia Optimistic future?