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| Titel |
The state of greenhouse gases in the atmosphere using global observations through 2013 |
| VerfasserIn |
Oksana Tarasova, Hiroshi Koide, Edward Dlugokencky, Stephen A. Montzka, Ralph Keeling, Toste Tanhua, Laura Lorenzoni |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250111954
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| Publikation (Nr.) |
 EGU/EGU2015-15173.pdf |
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| Zusammenfassung |
| We present results from the tenth annual Greenhouse Gas Bulletin
(http://www.wmo.int/pages/prog/arep/gaw/ ghg/GHGbulletin.html) of the World
Meteorological Organization (WMO). The results are based on research and observations
performed by laboratories contributing to the WMO Global Atmosphere Watch (GAW)
Programme (www.wmo.int/gaw).
The Bulletin presents results of global analyses of observational data collected according
to GAW recommended practices and submitted to the World Data Center for Greenhouse
Gases (WDCGG), and for the first time, it includes a summary of ocean acidification.
Bulletins are prepared by the WMO/GAW Scientific Advisory Group for Greenhouse Gases
(http://www.wmo.int/pages/prog/arep/gaw/ScientificAdvisoryGroups.html) in collaboration
with WDCGG. The summary of ocean acidification and trends in ocean pCO2 was jointly
produced by the International Ocean Carbon Coordination Project (IOCCP) of the
Intergovernmental Oceanographic Commission of UNESCO (IOC-UNESCO), the
Scientific Committee on Oceanic Research (SCOR), and the Ocean Acidification
International Coordination Centre (OA-ICC) of the International Atomic Energy Agency
(IAEA).
The tenth Bulletin included a special edition published prior to the United Nations
Climate Summit in September 2014. The scope of this edition was to demonstrate the level of
emission reduction necessary to stabilize radiative forcing by long-lived greenhouse gases. It
shows in particular that a reduction in radiative forcing from its current level (2.92 W m-2 in
2013) requires significant reductions in anthropogenic emissions of all major greenhouse
gases.
Observations used for global analysis are collected at more than 100 marine and
terrestrial sites worldwide for CO2 and CH4 and at a smaller number of sites for other
greenhouse gases. Globally averaged dry-air mole fractions of carbon dioxide, methane and
nitrous oxide derived from this network reached new highs in 2013, with CO2 at 396.0 ± 0.1
ppm, CH4 at 1824 ± 2 ppb and N2O at 325.9 ± 0.1 ppb. These values constitute 142%, 253%
and 121% of pre-industrial (before 1750) levels, respectively. The atmospheric increase of
CO2 from 2012 to 2013 was 2.9 ppm, which is the largest year to year change from 1984 to
2013. The rise of CO2 concentration has been only about a half of what is expected if all the
excess CO2 from the burning of fossil-fuel stayed in the air. The other half has
been absorbed by the land biosphere and the oceans, but the split between land and
oceans is not easily resolved from CO2 data alone. As described in the Bulletin, O2
measurements have been used to estimate the magnitude of the terrestrial biosphere
sink.
For N2O the increase from 2012 to 2013 is smaller than the one observed from 2011 to
2012 but comparable to the average growth rate over the past 10 years. Atmospheric CH4
continued to increase at a rate similar to the mean rate over the past 5 years. The National
Oceanic and Atmospheric Administration (NOAA) Annual Greenhouse Gas Index shows that
from 1990 to 2013 radiative forcing by long-lived greenhouse gases increased by 34%, with
CO2 accounting for about 80% of this increase. The radiative forcing by all long-lived
greenhouse gases in 2013 corresponded to a CO2-equivalent mole fraction of 479 ppm
(http://www.esrl.noaa.gov/gmd/aggi).
Uptake of anthropogenic CO2 by the ocean results in increased CO2 concentrations and
increased acidity levels in sea-water. During the last two decades ocean water pH decreased
by 0.0011 – 0.0024 per year, and the amount of CO2 dissolved in see water (pCO2)
increased by 1.2 - 2.8 μatm per year for time-series from several featured ocean
stations. |
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