Does global warming lag or lead a rise in greenhouse gas concentration? in The Azimuth Project

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**Does global warming lag or lead a rise in greenhouse gas concentration?** refers to a comparision of earth temperatures to concentrations of Green house gases (GHG). This page documents a discussion about the corresponding findings.

## Discussion ##

In a <a href="http://forum.azimuthproject.org/discussion/1163/global-warming-in-the-news/?Focus=8744#Comment_8744">comment in the Azimuth Forum</a> John Baez mentioned the article:

<a href=" http://www.sciencedirect.com/science/article/pii/S0921818112001658">• Ole Humlum, Kjell Stordahl, Jan-Erik Solheim, The phase relation between atmospheric carbon dioxide and global temperature, Global and Planetary Change 100 (2013), 51–69, http://www.sciencedirect.com/science/article/pii/S0921818112001658.</a>

which claims to show temperature changes precede changes in carbon dioxide concentration.

The article has a response on the blog realclimate:

<a href="http://www.realclimate.org/index.php/archives/2012/09/el-ninos-effect-onco2-causes-confusion/">El Nino’s effect on CO2 causes confusion about CO2′s role for climate change — rasmus @ 11 September 2012 </a>

which critizeses the findings.

## Charts ##

The article by Ole Humluma et al. provides the following chart

<div align = "center">
<img  src = "https://lh4.googleusercontent.com/-joWZ9IO3F7E/USaYYqNjT4I/AAAAAAAAAzY/VyQG7zwMxlE/w497-h373/humlum_co2_temperature_phase.jpg" alt = "humlum co2 temperature phase">
</div>


which was sort of reproduced by realclimate:

<div align = "center">
<img  src = "http://www.realclimate.org/images//hss2012fig2b-12-FALSEFALSEFALSE.png" alt = "realclimateimage">
</div>


where it was sofar not clear to the author of this Azimuth entry what DIFF12 means.

The US based "National climatic data center NOAA" provides the following chart in this context:

Temperature change and carbon dioxide change

<div align = "center">
<img  src = "http://www.ncdc.noaa.gov/paleo/globalwarming/images/temperature-change-small.jpg" alt = "NOAA chart temperature vs co2">
</div>

which displays that co2 concentrations are sometimes lagging behind and sometimes precede temperature changes.

The data is here however not directly measured (since the data goes back to 450 000 ys), which may explain why the the "lagging behind" or "preceding" looks as being sometimes in the range of 10000-30000 years.

In this context it <a href="http://forum.azimuthproject.org/discussion/1163/global-warming-in-the-news/?Focus=8752#Comment_8752">was pointed out</a> that it would also be interesting to see charts of other green house gases vs. temperature. In particular the co2 concentration seems to be connected with the methane concentrations. On the <a href="http://en.wikipedia.org/wiki/Methane#Atmospheric_methane">wikipedia page: Atmospheric methane</a> it was pointed out (23.02.2013) that: 

**Methane is created near the Earth’s surface, primarily by microorganisms by the process of methanogenesis. It is carried into the stratosphere by rising air in the tropics. Uncontrolled build-up of methane in the atmosphere is naturally checked — although human influence can upset this natural regulation — by methane’s reaction with hydroxyl radicals formed from singlet oxygen atoms and with water vapor. It has a net lifetime of about 10 years, (39) and is primarily removed by conversion to carbon dioxide and water.**

where the reference (39) is:

* Boucher, Olivier; Friedlingstein, Pierre; Collins, Bill; Shine, Keith P (2009). ["The indirect global warming potential and global temperature change potential due to methane oxidation"](http://iopscience.iop.org/1748-9326/4/4/044007/pdf/1748-9326_4_4_044007.pdf). [Environmental Research Letters 4: 044007](http://iopscience.iop.org/1748-9326/4/4/044007/). 

see also <a href="http://www.azimuthproject.org/azimuth/show/Methane#lifetime_of_methane_in_the_atmosphere_4">Lifetime of Methane in the atmossphere in the Azimuth project.</a>

Over half of the methane seems to be converted into co2, citation from p. 3 of Boucher et al:

_This gives a lower bound of 0.51... and an upper bound of 1.0 for the fraction of methane that is converted to carbon dioxide._

[[!redirects Global Warming]]
[[!redirects global warming]]

category:climate,carbon, global warming