Greenhouse gasses

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Atmospheric water vapor

Variations in the total column water vapour in the atmosphere since July 1983 according to The International Satellite Cloud Climatology Project (ISCCP). The upper graph (blue) shows the total amount of water in the atmosphere. The green graph shows the amount of water in the lower troposphere between 1000 and 680 mb, corresponding to altitudes up to about 3 km. The lower red graph shows the amount of water between 680 and 310 mb, corresponding to altitudes from about 3 to 6 km above sea level. The marked annual variation presumably reflects the asymmetrical distribution of land and ocean on planet Earth, with most land areas located in the northern hemisphere. The annual peak in atmospheric water vapour content occur usually around August-September, when northern hemisphere vegetation is at maximum transpiration. The annual moisture peak occurs simultaneously at different levels in the atmosphere, which suggests an efficient transport of water vapour from the planet surface up into the troposphere. The time labels indicate day/month/year. There is a possibility that the step-like change shown 1998-1999 to some degree may be related to changes in the analysis procedure used for producing the data set, according to information from ISCCP. Last data: June 2008. Last figure update: 14 June 2009.

 

Water vapour is the single most important greenhouse gas, and climate models forecast an increasing amount of atmospheric water vapour along with global temperature increase, because of enhanched evaporation of water from the planet surface.

In addition to its direct greenhouse effect, water vapor is also important for cloud formation. Click here to see a few notes on this.

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Atmospheric carbon dioxide (CO2)

Monthly average of carbon dioxide in the mid-troposphere made from data acquired by AIRS during July 2009. Source: NASA Jet Propulsion Laboratory AIRS.

 

Monthly amount of atmospheric CO2 since March 1958, measured at the Mauna Loa Observatory, Hawaii. Data are reported as a dry mole fraction defined as the number of molecules of carbon dioxide divided by the number of molecules of dry air (water vapor removed), multiplied by one million (ppm). The thin line shows the monthly values, while the thick line is the simple running 37 month average, nearly corresponding to a running 3 yr average. IPCC = foundation of the International Panel on Climate Change (November 1988). Last month shown: June 2010. Last diagram update: 9 July 2010.

  • Click here to download the entire series of monthly CO2 values since March 1958.

  • Click here to read about data smoothing.

 

Annual (12 month) growth rate (ppm) of atmospheric CO2 since 1959, calculated as the average amount of atmospheric CO2 during the last 12 months, minus the average for the preceding 12 months. The graph is based on data measured at the Mauna Loa Observatory, Hawaii. Data are reported as a dry mole fraction defined as the number of molecules of carbon dioxide divided by the number of molecules of dry air (water vapor removed), multiplied by one million (ppm). The thin line shows the value calculated month by month, while the thick line represents the simple running 3 year average. IPCC = foundation of the International Panel on Climate Change (November 1988). Last month shown: June 2010. Last diagram update: 9 July 2010.

  • Click here to download the entire series of monthly CO2 values since March 1958.

  • Click here to read about data smoothing.

 

Atmospheric CO2 is measured at several sites distributed across the planet surface. Click on the link below see results from these measurement stations:

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Temperature records versus atmospheric CO2

Superimposed plot of five different global monthly temperature estimates shown above, after setting January 1979 = 0. Click here to go to the associated comparison of these five temperature records. The heavy black line represents the simple running 37 month (c. 3 year) mean of the average of all five temperature records. The graph showing the amount of atmospheric CO2 is based on data from the Mauna Loa station, Hawaii, see also above. For the first two decades in the 21th century a warming of about 0.2°C per decade is projected for a range of SRES emission scenarios according to the 2007 IPCC Summary for Policymakers (p.7 and Fig.SPM.5). For comparison, the rate of this projected temperature increase is shown by the grey stippled line. Last month shown: May 2010. Last diagram update: 29 June 2010.

 

Diagram showing the HadCRUT3 monthly global surface air temperature estimate (blue) and the monthly atmospheric CO2 content (red) according to the Mauna Loa Observatory, Hawaii. The Mauna Loa data series begins in March 1958, and 1958 has therefore been chosen as starting year for the diagram. Reconstructions of past atmospheric CO2 concentrations (before 1958) are not incorporated in this diagram, as such past CO2 values are derived by other means (ice cores, stomata, or older measurements using different methodology), and therefore are not directly comparable with modern atmospheric measurements. The dotted grey line indicates the approximate linear temperature trend, and the boxes in the lower part of the diagram indicate the relation between atmospheric CO2 and global surface air temperature, negative or positive. The annotation "IPCC" indicate the establishment of the Intergovernmental Panel on Climate Change in 1988. Last month shown: June 2010. Last diagram update: 22 July 2010.

 

Diagram showing the GISS monthly global surface air temperature estimate (blue) and the monthly atmospheric CO2 content (red) according to the Mauna Loa Observatory, Hawaii. The Mauna Loa data series begins in March 1958, and 1958 has therefore been chosen as starting year for the diagram. Reconstructions of past atmospheric CO2 concentrations (before 1958) are not incorporated in this diagram, as such past CO2 values are derived by other means (ice cores, stomata, or older measurements using different methodology), and therefore are not directly comparable with modern atmospheric measurements. The dotted grey line indicates the approximate linear temperature trend, and the boxes in the lower part of the diagram indicate the relation between atmospheric CO2 and global surface air temperature, negative or positive. The annotation "IPCC" indicate the establishment of the Intergovernmental Panel on Climate Change in 1988. Last month shown: June 2010. Last figure update: 13 July 2010.

 

Diagram showing the NCDC monthly global surface air temperature estimate (blue) and the monthly atmospheric CO2 content (red) according to the Mauna Loa Observatory, Hawaii. The Mauna Loa data series begins in March 1958, and 1958 has therefore been chosen as starting year for the diagram. Reconstructions of past atmospheric CO2 concentrations (before 1958) are not incorporated in this diagram, as such past CO2 values are derived by other means (ice cores, stomata, or older measurements using different methodology, and therefore are not directly comparable with modern atmospheric measurements. The dotted grey line indicates the approximate linear temperature trend, and the boxes in the lower part of the diagram indicate the relation between atmospheric CO2 and global surface air temperature, negative or positive. The annotation "IPCC" indicate the establishment of the Intergovernmental Panel on Climate Change in 1988. Last month shown: June 2010. Last diagram update: 16 July 2010.

 

Most climate models assume the greenhouse gas carbon dioxide CO2 to influence significantly upon global temperature. It is therefore relevant to compare different temperature records with measurements of atmospheric CO2, as shown in the diagrams above. Any comparison, however, should not be made on a monthly or annual basis, but for a longer time period, as other effects (oceanographic, etc.) may well override the potential influence of CO2 on short time scales such as just a few years. It is of cause equally inappropriate to present new meteorological record values, whether daily, monthly or annual, as support for the hypothesis ascribing high importance of atmospheric CO2 for global temperatures. Any such short-period meteorological record value may well be the result of other phenomena.

What exactly defines the critical length of a relevant time period to consider for evaluating the alleged importance of CO2 remains elusive, and is still a topic for debate. The critical period length must, however, be inversely proportional to the temperature sensitivity of CO2, including feedback effects, such as assumed by most standard climate models. 

After about 10 years of global temperature increase, IPCC was established in 1988. Presumably, several scientists interested in climate then felt intuitively that their empirical and theoretical understanding of climate dynamics was sufficient to conclude about the importance of CO2 for global temperature. However, for obtaining public and political support for the CO2-hyphotesis the 10 year warming period leading up to 1988 in all likelihood was important. Had the global temperature instead been decreasing, public support for the hypothesis would have been difficult to obtain. Adopting this approach as to critical time length, the varying relation (positive or negative) between global temperature and atmospheric CO2 has been indicated in the lower panels of the diagrams above.

Click here to read a few reflections on the relation between global temperature and the amount of atmospheric CO2.  

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Atmospheric methane (CH4)

Plot showing showing the growth of atmospheric methane (in the marine boundary layer), the seasonal variations and the difference between northern and southern hemispheres (NOAA, GLOBALVIEW), from 1993 to 2002.

 

 

Diagram showing variations of atmospheric CH4 since 1984 at Storhofdi, Vestmannaeyjar, Iceland (63.40 N, 20.29 W) and Tasmania, Australia (40.53 S, 144.30 E). The thin lines show weekly values, while the thick lines show the running annual average value. The Vestmannaeyjar observatory is located 127 m above sea level. The Tasmania measurements are carried out from aircraft between 0 and 1000 m above sea level. Last diagram update: 11 April 2010.

  • Click here to download the Vestmannaeyjar data record since 1984.

  • Click here to download the Tasmania data record since 1984.

  • Click here to read about data smoothing.

 

Atmospheric methane (CH4) is measured at several sites distributed across the planet surface. Click on the link below see results from these measurement stations:

 

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