Controversial new climate change results
University of Bristol Press release issued 9 November 2009
New data show that the balance between the airborne and the absorbed fraction of carbon dioxide has stayed approximately constant since 1850, despite emissions of carbon dioxide having risen from about 2 billion tons a year in 1850 to 35 billion tons a year now.
This suggests that terrestrial ecosystems and the oceans have a much greater capacity to absorb CO2 than had been previously expected.
The results run contrary to a significant body of recent research which expects that the capacity of terrestrial ecosystems and the oceans to absorb CO2 should start to diminish as CO2 emissions increase, letting greenhouse gas levels skyrocket. Dr Wolfgang Knorr at the University of Bristol found that in fact the trend in the airborne fraction since 1850 has only been 0.7 ± 1.4% per decade, which is essentially zero.
The strength of the new study, published online in Geophysical Research Letters, is that it rests solely on measurements and statistical data, including historical records extracted from Antarctic ice, and does not rely on computations with complex climate models.
This work is extremely important for climate change policy, because emission targets to be negotiated at the United Nations Climate Change Conference in Copenhagen early next month have been based on projections that have a carbon free sink of already factored in. Some researchers have cautioned against this approach, pointing at evidence that suggests the sink has already started to decrease.
So is this good news for climate negotiations in Copenhagen? “Not necessarily”, says Knorr. “Like all studies of this kind, there are uncertainties in the data, so rather than relying on Nature to provide a free service, soaking up our waste carbon, we need to ascertain why the proportion being absorbed has not changed”.
Another result of the study is that emissions from deforestation might have been overestimated by between 18 and 75 per cent. This would agree with results published last week in Nature Geoscience by a team led by Guido van der Werf from VU University Amsterdam. They re-visited deforestation data and concluded that emissions have been overestimated by at least a factor of two.
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Here is the abstract from GRL:
Several recent studies have highlighted the possibility that the oceans and terrestrial ecosystems have started losing part of their ability to sequester a large proportion of the anthropogenic CO2 emissions. This is an important claim, because so far only about 40% of those emissions have stayed in the atmosphere, which has prevented additional climate change.
This study re-examines the available atmospheric CO2 and emissions data including their uncertainties. It is shown that with those uncertainties, the trend in the airborne fraction since 1850 has been 0.7 ± 1.4% per decade, i.e. close to and not significantly different from zero. The analysis further shows that the statistical model of a constant airborne fraction agrees best with the available data if emissions from land use change are scaled down to 82% or less of their original estimates. Despite the predictions of coupled climate-carbon cycle models, no trend in the airborne fraction can be found.
Knorr, W. (2009), Is the airborne fraction of anthropogenic CO2 emissions increasing?, Geophys. Res. Lett., 36, L21710, doi:10.1029/2009GL040613.
According to Pat Michaels at World Climate Report:
Dr. Knorr carefully analyzed the record of anthropogenic CO2 emissions, atmospheric CO2 concentrations, and anthropogenic land-use changes for the past 150 years. Keeping in mind the various sources of potential errors inherent in these data, he developed several different possible solutions to fitting a trend to the airborne fraction of anthropogenic carbon dioxide emissions. In all cases, he found no significant trend (at the 95% significance level) in airborne fraction since 1850.
(Note: It is not that the total atmospheric burden of CO2 has not been increasing over time, but that of the total CO2 released into the atmosphere each year by human activities, about 45% remains in the atmosphere while the other 55% is taken up by various natural processes—and these percentages have not changed during the past 150 years)
Here is Figure 1 from the Knorr paper:
Figure 1. The annual increase in atmospheric CO2 (as determined from ice cores, thin dotted lines, and direct measurements, thin black line) has remained constantly proportional to the annual amount of CO2 released by human activities (thick black line). The proportion is about 46% (thick dotted line). (Figure source: Knorr, 2009)
The conclusion of the Knorr paper reads:
Given the importance of the [the anthropogenic CO2 airborne fraction] for the degree of future climate change, the question is how to best predict its future course. One pre-requisite is that we gain a thorough understand of why it has stayed approximately constant in the past, another that we improve our ability to detect if and when it changes. The most urgent need seems to exist for more accurate estimates of land use emissions.
Another possible approach is to add more data through the combination of many detailed regional studies such as the ones by Schuster and Watson (2007) and Le Quéré et al. (2007), or using process based models combined with data assimilation approaches (Rayner et al., 2005). If process models are used, however, they need to be carefully constructed in order to answer the question of why the AF has remained constant and not shown more pronounced decadal-scale fluctuations or a stronger secular trend.
Michaels adds:
In other words, like we have repeated over and over, if the models can’t replicate the past (for the right reasons), they can’t be relied on for producing accurate future projections. And as things now stand, the earth is responding to anthropogenic CO2 emissions in a different (and perhaps better) manner than we thought that it would.
Yet here we are, on the brink of economy crippling legislation to tackle a problem we don’t fully understand and the science is most certainly not settled on.
UPDATE: A professional email list I’m on is circulating the paper, read it here: Knorr 2009_CO2_sequestration
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Excuse me if someone already covered this. First off, I wish those Bristoliers would speak English…..””” New data show that the balance between the airborne and the absorbed fraction of carbon dioxide has stayed approximately constant since 1850, “””
What on earth does that mean? If it means that the ratio of atmospheric CO2 to Oceanic CO2 hasn’t changed; why not say that, sow e know what you are talking about. I find that the ability of scientists to write decent English, and say what they mean, is abyssmal. When somebody says “balanced” I see a teeter-totter (see-saw to some).
Is this Bristoian revelation some new pronouncement of Henry’s Law ? Isn’t that ratio supposed to stay constant; well assuming other physical parameters stay the same ?
There is one other thing about the Ocean CO2 takeup that constantly bothers me.
We are told that the solubility of CO2 in sea water is a function of temperature; and in particular it is more soluble in colder warers.
We also know that the ocean water temperature tends to fall as you go deeper.
That seems to imply that CO2 is less soluble in the warmer surface waters than the deeper colder waters, and my elementary chemistry says that therefoire CO2 ought to diffuse out of the warmer surface waters into the colder deeper waters setting up a pumping action that continually sends CO2 into the depths.
The Henry’s Law equilibrium bwtween ocean and atmosphere; to the extent that it ever reaches equilibrium, would be between the warm surface waters and the atmosphere.
Those warmer surface waters ought to be constantly depleted by the diffusion to colder deeper waters, so the surface waters are constantly taking up more CO2 out of the atmosphere. Of course as temperatures fluctuate, that equilibrium would shift either to outgas CO2 or take up more.
Bottom line is that I believe that the oceans do not look like a sponge that is saturated with CO2. The warm surface waters can take up CO2 out of the atmosphere just as fast as the diffusion due to the water temperature gradient, can transport it to colder deeper waters.
Now if SSTs then increase, so the surface loses CO2 to the atmosphere, and also to the cooler deeper waters; that would seem to me to result in a surface depleted in CO2.
Chemical and biologivcal processes that take up CO2 and end up forming calcium carbonate, or other carbonates, in skeletons or other ocean body parts, would seem to remove carbon from the water, more or less permanently.
And as we now know from Jane Lubchenko’s remarkable experiment; Corals and sea shells, cannot grow in ordinary tap water containing Chlorine and perhaps Fluoride, that has been dyed yellow with an ordinary laboratory yellow dye, and chilled with dry ice; but they presumably can grow in ordinary tap water, with Chlorine and Fluoride, that is dyed blue with a common lab blue dye at room temperature.
Somlpy amazing what one can learn from these scientific geniuses that President Obama has brought into his administration.
I’m waiting for some grad student to apply for a government grant to see if corals can be made to grow in ordinary sea water; preferrably obtained from the immediate vicinity of a coral reef; once it has been dyed blue with a common laboratory blue dye; and also to see if that sea water turns yellow when it is chilled with pounds of dry ice as demonstrated in Lubchenko’s experiment.
Those published figures above are incorrect. The author has simply taken annual global world Carbon production for 1850, 50E6 metric tons, and (the latest I have from CDIAC is year 2006) 8230E6 metric tons and converted these figures to CO2; assuming all this goes to the atmosphere.
Not so. 2006 CO2 to atmosphere is as follows: Using Chemical Equations for burning of Natural Gas + and Engineering Orsat Analysis for the combustion of same in a chamber, the amount of fuel converted to CO2 and that goes to the atmosphere is 3.05E9 metric tons of CO2(2006). That is 1.43 ppmv to the atmosphere. I verified this using Schack 1973 estimate of CO2 increases to the atmosphere. The values, calculated differently, agree within fractions of a percent.
This is even worse for the AGW proponents, because at that “offset” rate (If we suddenly stopped Carbon production now), it would take over 100 years to save 1 ºCelsius. So, what’s the point in trying to reduce emissions? No point at all.
The research is sound,its use in this context is flawed.
1) As the reports author has already asserted, the findings suggest that the oceans only slow the rate at which CO2 is increasing in the atmosphere. Tackling the emissions is still an essential for our planets health.
2) CO2 dissolves in water to form Carbolic acid. Acidification of the oceans is one of the by-products of CO2 emissions, harmful to our oceans, especially shell and reef forming creatures
Look at this research carefully. This interpretation is facile.