CO2 as a Climate Change Tracer Gas - EPICA scaled CO2

The EPICA Dome C CO2 data from the Antarctic Ice Cores Nature, Vol. 453, pp.79-382, 15 May 2008.(doi:10.1038/nature06949) are a well known standard in climate science.  In order to make them a more versitile standard, I have created a scaled version using the Bintanja, R. and R.S.W. van de Wal. 2011 (BW) (doi:10.1038/nature07158 ). Global 3Ma Temperature, Sea Level, and Ice Volume Reconstructions. deep ocean temperature (Tdo).

The CO2 data is scale by using the average, 239.1 ppmv for the past 100 k years and subtracting to obtain an anomaly.  Then the data is divided by 30 to scale to the Tdo curve and 1.25 is subtracted to match the relative temperature of "today" used by BW.

This chart shows the fit of the scale EPICA CO2 data to the BW Tdo.

This chart shows the fit to the Martinez-Garcia et al 2010 sub-Antarctic temperature reconstruction(OPD1090) and Tropical Eastern Pacific (OPD846) from Herbert et al. 2010.  Since I will be using this "standard" version of EPICA CO2, this post is provided for reference.

"Global" versus the Oceans - Part Three

With grand plans of connecting Antarctic sea ice and the Circumpolar Current to not only climate change but geomagnetic field reversals, there needs to be a solid reference to trace events back through time.  Bantanja and van de Wal provide a remarkable well constructed set of data for 45N to the pole.  But 45N to the pole is not "Global".

Using the BW Tdo or Temperature of the deep ocean and the EPICA CO2 reconstruction you can scale and offset Antarctic reconstructed CO2 to very closely match North Atlantic deep ocean water temperature.  Since BW reference temperatures to "today", their reconstruction provides the baseline value.  In order to scale the CO2 data, the average for the period 0 to 100 k years was determined, (239.1 ppmv) then the anomaly was created by subtracting the average from the individual data point.  Then to convert to "today" 1.25 was subtracted from the anomaly.  The fit is not perfect but reasonable considering the data sets are from opposite poles.

The scaled CO2 and the BW Tdo allow simple comparison of a reference "standard" to other data sets.  Here the Pahnke, K., and J.P. Sachs. 2007 Sea surface temperatures of southern midlatitudes 0–160 kyr B.P. Paleoceanography, 21, PA2003, doi:10.1029/2005PA001191, data is used.  The SO 1 is Core MD97-2120: 45°32.060S, 174°55.850E, 1210m water depth and SO2 is Core MD97-2121: 40°22.80S,  177°59.40E,  3014m water depth.  The arrows on the plot point out a convergence at ~80ka and a divergence at ~148ka. The fit is very noisy, not unexpected, but comfortably close with the exception of the interesting divergence.

   This is a little more controversial comparison.  The Martin et al. 2002 Bottom Water Temperatures, (Tropical Atlantic Core M16772:    1°21'S, 11°58'W, 3912m water depth.  also labeled as M16722 in the Excel download and Tropical Pacific Core TR163-31P:  3°35'S, 83°57'W, 3205m water depth.) have what I call an inverse relation to CO2 following a perturbation.  The Tropical Pacific core is more consistently warming while CO2 concentration decreases but the Tropical Atlantic also other than an abrupt change at ~80ka has a similar divergence from the CO2 trend.  Compared the the Pahnke data sets, the fit is terrible.  That terrible fit though could be an indication of ACC impact on the ThermoHaline Current (THC).

Note: Core ODP 846 is actually tropical eastern Pacific not sub-Antarctic.  Text below revised.

Martinez-Garcia et al. 2010, Subantarctic Atlantic and Subarctic Pacific 3.6 Ma Alkenone SST Reconstructions. (DOI:10.1126/science.1184480) has an interesting fit with the scaled CO2.  The scaled CO2 does not fit either data set perfectly but does tend to follow the combined sets with emphasis more on one than the other at some points.  The slope of the scaled CO2 is nearly a perfect match of the slopes of the sub-Antarctic and Eastern Pacific temperature reconstructions.  The oscillations between the two temperature sets should provide some information on changes in the ACC and its impact on the THC.

Since the EPICA core does not extend far enough back in time for a continuous "standard", a combination of the BW Tdo and the Herbert et al. Tropical Oceans may be required for the next step back in time.

Global Water Versus Land Area Reference

This is revision of a copy of the Kossinna 1921 Distribution of water and land by 5 degree parallels from the link cdlib.org.  The values are in million kilometers squared.

Unless I have transcription errors, this the data from the North Pole to the south.



Lots of land up here.


















Lots of water down here.

Between latitude 40S and 60S, there is 23% of all the global ocean surface area and 1.6% of all the global land surface area.  Since the oceans have much greater thermal mass that land, nearly a quarter of the thermal mass of the globe is confined to this 20 degree band of latitude.  This happens to be the home of the Antarctic Circumpolar Current.

A five degree latitude change in the ACC path caused by atmospheric circulation patterns and/or change in the sea ice extent would impact global climate significantly.  No need to think albedo forcing, just simple thermodynamics.  This area is the window to the thermally isolated continent of Antarctica with an average annual temperature of around -30 C degrees, where an area the size of the continent of Australia changes from open water to sea ice every year.  

This table makes a nice reference.  More than twice the surface area of the Earth is between 45N and 45S, the land of sunshine.  Nearly half of the surface is between latitude 25N and 25S in the tropical zone and only 53.3 million kilometers squared of 214.7 million kilometers squared total is land surface in the tropical zone.  Between ~45N and 90N,  there are 30.8 million kilometers squared of ocean, ~8.5% of the 361 million kilometers squared of total ocean surface area and 37% of the ocean surface area between 40S and 60S.