| Название | : | Climate change impacts on coral reefs (Great Barrier Reef Marine Park Authority) |
| Продолжительность | : | 1.22 |
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| Просмотров | : | 14 rb |
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According to the Vostok Ice Core Records, CO2 level changes have followed Earth's overall temperature changes at an 800 year lag for the last 800,000 years That means that our current CO2 levels are the result of Earth's overall temperature 800 years ago World leaders have convinced their dependents that this works in the reverse order, relatively quickly, and that we are to blame, so that they can tax us out of a false shared guilt in order to be able to afford to "fight" climate change, an unstoppable natural cycle The following is the source of this information:brbrHistorical Carbon Dioxide Record from the Vostok Ice CorebrbrInvestigatorsbrJ-M Barnola, D Raynaud, C LoriusbrLaboratoire de Glaciologie et de Géophysique de l'Environnement,brCNRS, BP96,br38402 Saint Martin d'Heres Cedex, FrancebrbrNI BarkovbrArctic and Antarctic Research Institute,brBeringa Street 38, 199397,brSt Petersburg, RussiabrbrPeriod of Recordbr417,160 - 2,342 years BPbrbrMethodsbrIn January 1998, the collaborative ice-drilling project between Russia, the United States, and France at the Russian Vostok station in East Antarctica yielded the deepest ice core ever recovered, reaching a depth of 3,623 m (Petit et al 1997, 1999) Ice cores are unique with their entrapped air inclusions enabling direct records of past changes in atmospheric trace-gas composition Preliminary data indicate the Vostok ice-core record extends through four climate cycles, with ice slightly older than 400 kyr (Petit et al 1997, 1999) Because air bubbles do not close at the surface of the ice sheet but only near the firn-ice transition (that is, at 90 m below the surface at Vostok), the air extracted from the ice is younger than the surrounding ice (Barnola et al 1991) Using semiempirical models of densification applied to past Vostok climate conditions, Barnola et al (1991) reported that the age difference between air and ice may be 6000 years during the coldest periods instead of 4000 years, as previously assumed Ice samples were cut with a bandsaw in a cold room (at about -15°C) as close as possible to the center of the core in order to avoid surface contamination (Barnola et al 1983) Gas extraction and measurements were performed with the "Grenoble analytical setup," which involved crushing the ice sample (40 g) under vacuum in a stainless-steel container without melting it, expanding the gas released during the crushing in a pre-evacuated sampling loop, and analyzing the CO2 concentrations by gas chromatography (Barnola et al 1983) The analytical system, except for the stainless-steel container in which the ice was crushed, was calibrated for each ice sample measurement with a standard mixture of CO2 in nitrogen and oxygen For further details on the experimental procedures and the dating of the successive ice layers at Vostok, see Barnola et al (1987, 1991), Lorius et al (1985), and Petit et al (1999)brbrTrendsbrThere is a close correlation between Antarctic temperature and atmospheric concentrations of CO2 (Barnola et al 1987) The extension of the Vostok CO2 record shows that the main trends of CO2 are similar for each glacial cycle Major transitions from the lowest to the highest values are associated with glacial-interglacial transitions During these transitions, the atmospheric concentrations of CO2 rises from 180 to 280-300 ppmv (Petit et al 1999) The extension of the Vostok CO2 record shows the present-day levels of CO2 are unprecedented during the past 420 kyr Pre-industrial Holocene levels (280 ppmv) are found during all interglacials, with the highest values (300 ppmv) found approximately 323 kyr BP When the Vostok ice core data were compared with other ice core data (Delmas et al 1980; Neftel et al 1982) for the past 30,000 - 40,000 years, good agreement was found between the records: all show low CO2 values [200 parts per million by volume (ppmv)] during the Last Glacial Maximum and increased atmospheric CO2 concentrations associated with the glacial-Holocene transition According to Barnola et al (1991) and Petit et al (1999) these measurements indicate that, at the beginning of the deglaciations, the CO2 increase either was in phase or lagged by less than 1000 years with respect to the Antarctic temperature, whereas it clearly lagged behind the temperature at the onset of the glaciationsbrbrReferencesbrBarnola, J-M, D Raynaud, A Neftel, and H Oeschger 1983 Comparison of CO2 measurements by two laboratories on air from bubbles in polar ice Nature 303:410-13brbrBarnola, J-M, D Raynaud, YS Korotkevich, and C Lorius 1987 Vostok ice core provides 160,000-year record of atmospheric CO2 Nature 329:408-14brbrBarnola, J-M, P Pimienta, D Raynaud, and YS Korotkevich 1991 CO2-climate relationship as deduced from the Vostok ice core: A re-examination based on new measurements and on a re-evaluation of the air dating Tellus 43(B):83- 90brbrDelmas, RJ, J-M Ascencio, and M Legrand 1980 Polar ice evidence that atmospheric CO2 20,000 yr BP was 50 of present Nature 284:155-57brbrJouzel, J, C Lorius, JR Petit, C Genthon, NI Barkov, VM Kotlyakov, and VM Petrov 1987 Vostok ice core: A continuous isotopic temperature record over the last climatic cycle (160,000 years) Nature 329:403-8brbrLorius, C, J Jouzel, C Ritz, L Merlivat, NI Barkov, YS Korotkevich, and VM Kotlyakov 1985 A 150,000-year climatic record from Antarctic ice Nature 316:591-96brbrNeftel, A, H Oeschger, J Schwander, B Stauffer, and R Zumbrunn 1982 Ice core measurements give atmospheric CO2 content during the past 40,000 yr Nature 295:220-23brbrPepin, L, D Raynaud, J-M Barnola, and MF Loutre 2001 Hemispheric roles of climate forcings during glacial-interglacial transitions as deduced from the Vostok record and LLN-2D model experiments Journal of Geophysical Research 106 (D23): 31,885-31,892brbrPetit, JR, I Basile, A Leruyuet, D Raynaud, C Lorius, J Jouzel, M Stievenard, VY Lipenkov, NI Barkov, BB Kudryashov, M Davis, E Saltzman, and V Kotlyakov 1997 Four climate cycles in Vostok ice core Nature 387: 359-360brbrPetit, JR, J Jouzel, D Raynaud, NI Barkov, J-M Barnola, I Basile, M Benders, J Chappellaz, M Davis, G Delayque, M Delmotte, VM Kotlyakov, M Legrand, VY Lipenkov, C Lorius, L Pépin, C Ritz, E Saltzman, and M Stievenard 1999 Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica Nature 399: 429-436brbrRaynaud, D, and J-M Barnola 1985 An Antarctic ice core reveals atmospheric CO2 variations over the past few centuries Nature 315:309-11brbrCITE AS: Barnola, J-M, D Raynaud, C Lorius, and NI Barkov 2003 Historical CO2 record from the Vostok ice core In Trends: A Compendium of Data on Global Change Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, US Department of Energy, Oak Ridge, Tenn, USAbrbrRevised February 2003 Comment from : Jason Melton |
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pretty good video here Comment from : Christopher Tan |
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