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Where have those fossil fuel emissions gone?

Posted By Joanne Nova On November 10, 2014 @ 2:50 am In Global Warming | Comments Disabled

Oh the paradox! Human emissions upset the delicate balance and drive up global CO2 levels by 2ppm a year, but lordy, at the same time, that delicate balance roils and rolls with the seasons by a far larger range. Get the feeling there is more to Life on Earth than humans?

There are places on Earth when CO2 swings every year by 16ppm or more – like Point Barrow. Then there are places like the South Pole, where it barely changes all year round — a bit like the level of greenery there which varies from white to white. And there’s a clue. The other part of the world where CO2 levels don’t swing is at the equator — where it’s 100% green all year long. The big changes in terrestrial CO2 occur in the zones where plant life ebbs and flows.

Tom Quirk tracks the seasonal shifts in CO2 and finds that the northern Boreal forests are probably drawing down something like 2 – 5 gigatons of CO2 every year, and because the seasonal amplitude is getting larger each year, it suggests there is no sign of saturation.  Those plants are not bored of extra CO2 yet. This fits with Craig Idso’s work on plant growth which demonstrates that the saturation point — where plants grow as fast as possible (and extra CO2 doesn’t help) is somewhere above 1000 and below 2000ppm. We have a long way to go.

Burn oil, feed the starving plants of the world I say!  — Jo

Figure 3: Satellite derived measurements[4] of changes in net primary productivity (NPP) which is the net intake of CO2 by plants. The tropical forests and the boreal forests in the far North show NPP of 1.0 to 1.5% annual growth.


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Where have fossil fuel emissions gone?

 Guest Post by Tom Quirk

The standard explanation for the yearly rise in atmospheric CO2 is that it is due entirely to fossil fuel and cement production emissions. However if the recent analysis[1] of the isotopic composition of atmospheric CO2 is correct then only a fraction say 10% of fossil fuel emissions find their way into the atmosphere.

If only a fraction of fossil fuel CO2 emissions finds its way into the “well mixed “ atmosphere, what sinks have the capacity to absorb the balance?

One of the clues comes from the growth in the amplitude of the yearly seasonal variations of atmospheric CO2. This analysis assumes that the growth in the seasonal amplitude is a result of increasing vegetation, a “greening of the earth”.

The Scripps Institute of Oceanography (SIO) provides both raw and smoothed time series measurements of atmospheric CO2. The smoothed data has had the seasonal variations removed. Thus the difference of the raw from the smoothed measurements exposes the seasonal variations. Seasonal variations are shown in Figure 1 for two examples from Mauna Loa and Point Barrow.

Figure 1: Seasonal variation extracted from raw and smoothed measurements (SIO)


The amplitudes for the seasonal variations are shown in Figure 2 for a number of latitudes.

The changes in seasonal amplitude extracted from the SIO analysis are given in Table 1.

 

Table 1 Seasonal variation data derived from SIO analysis

1

2

3

4           5

6

Location

Period

Month for minimum CO2

Seasonal amplitudes ppm

Annual increases

in seasonal amplitudes

Initial

Final

ppm per year

82 N Alert

1985-2010

August

14.17

16.01

0.074

71 N Point Barrow

1974-2010

August

14.55

17.98

 0.095

33 N La Jolla

1969-2010

August

  8.51

12.44

 0.096

19 N Kumukahi

1979-2010

September

  7.97

  8.77

 0.025

20 N Mauna Loa

1960-2010

September

  6.04

  6.99

 0.019

  2 N Christmas Island

1975-2010

October

  2.93

  2.94

 0.000

14 S American Samoa

1982-2010

February

  0.61

  0.99

0.014

29 S Kermadec

1984-2009

May

  0.97

  0.96

0.000

41 S Baring Head

1978-2009

January

 1.04

  1.04

0.000

90 S South Pole

1960-2010

March

 1.06

  1.03

-0.001

 

The analysis shows that the seasonal growth increases occur in the northern latitudes of the Northern Hemisphere. This is where the Boreal forests and peatlands of Canada and Russia (and other lesser forest) are estimated to contain some 350 Gt of carbon.

There are a number of estimates of forest growth:

Sweden2: “tree basal area and biomass increased by 19% between 1997 and 2010 with the main increase occurring in established birch forest,”

Russia3: Over the period 1961-1998, Lapenis et al. found that “aboveground wood, roots, and green parts increased by 4%, 21%, and 33%, respectively,” such that “the total carbon density of the living biomass stock of the Russian forests increased by ~9% from 4.08 to 4.44 kg C m-2.” In addition, they report there was an “increase in the area of the Russian forests (from 695.5 x 1010 m2 in 1961 to 774.2 x 1010 m2 in 1998),” which equates to ~11%.

Europe4: “An upwards trend of forest NEP (Net Ecosystem Productivity) of 1 ± 0.5 g C/m2/year between 1950 and 2000 across the EU 25,” ending with “a mean European forest NEP of 175 ± 52 g C/m2/year in the 1990s.” And that “61% of the change in NEP [over the last half of the 20th century] was attributed to changes in CO2, 26% to changes in climate, and 13% to changes in forest age structure.”

These three reports give an annual forest growth of between 0.5% and 1.6% while the annual growth rates for the seasonal variations are between 0.5% and 0.9%.

While no growth in the seasonal variation appears at Christmas Island (20 N) and little in Hawaii (190 N), these seasonal variations are a reflection of the more northern latitudes mixing into the lower latitudes.

So using just the boreal forest estimates from Canada and Russia would give a carbon sink with an annual removal of 1.9 to 5.5 Gt C of CO2 from the atmosphere. This sink would operate during the summer months as would temperate zone forests. However there are satellite analyses showing growth in the tropical region that has not been taken into account.

NASA satellite data5 suggest that for more than two decades there has been a gradual greening of plants on a global scale.

In particular, in the northern latitudes of Earth the growth has been as much as 1.5% annually.

 

Figure 3: Satellite derived measurements[4] of changes in net primary productivity (NPP) which is the net intake of CO2 by plants. The tropical forests and the boreal forests in the far North show NPP of 1.0 to 1.5% annual growth.


Unless there is an alternative explanation for the growth of the seasonal CO2 amplitude, it is a strong indicator of forest growth. In addition it shows no sign of saturation.

 


1   See Figure 3 of http://quadrant.org.au/opinion/doomed-planet/2013/09/ipcc-never-taken-seriously/
2   Hedenas, H., Olsson, H., Jonasson, C., Bergstedt, J., Dahlberg, U. and Callaghan, T.V. 2011. Changes in tree growth, biomass and vegetation over a 13-year period in the Swedish Sub-Arctic. Ambio 40: 672-682.
3  Lapenis, A., Shvidenko, A., Shepaschenko, D., Nilsson, S. and Aiyyer, A. 2005. Acclimation of Russian forests to recent changes in climate. Global Change Biology 11: 2090-2102.
4  Bellassen, V., Viovy, N., Luyssaert, S., Le Marie, G., Schelhaas, M.-J. and Ciais, P. 2011. Reconstruction and attribution of the carbon sink of European forests between 1950 and 2000. Global Change Biology 17: 3274-3292.

5   http://earthobservatory.nasa.gov/Features/GlobalGarden

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