No Rise of Atmospheric Carbon Dioxide Fraction in

[scpg02]

No Rise of Atmospheric Carbon Dioxide Fraction in Past 160 Years, New Research Finds

ScienceDaily (Dec. 31, 2009) — Most of the carbon dioxide emitted by human activity does not remain in the atmosphere, but is instead absorbed by the oceans and terrestrial ecosystems. In fact, only about 45 percent of emitted carbon dioxide stays in the atmosphere.

However, some studies have suggested that the ability of oceans and plants to absorb carbon dioxide recently may have begun to decline and that the airborne fraction of anthropogenic carbon dioxide emissions is therefore beginning to increase.

Many climate models also assume that the airborne fraction will increase. Because understanding of the airborne fraction of carbon dioxide is important for predicting future climate change, it is essential to have accurate knowledge of whether that fraction is changing or will change as emissions increase.

To assess whether the airborne fraction is indeed increasing, Wolfgang Knorr of the Department of Earth Sciences at the University of Bristol reanalyzed available atmospheric carbon dioxide and emissions data since 1850 and considers the uncertainties in the data.

In contradiction to some recent studies, he finds that the airborne fraction of carbon dioxide has not increased either during the past 150 years or during the most recent five decades.

The research is published in Geophysical Research Letters.

www.sciencedaily.com/releases/2009/12/091230184221.htm

[glc]

Re: the study

I'm pretty sure this has been discussed before on this blog. This has been known about for some time. However, even if the airborne proportion remains at ~45%, atmospheric CO2 concentrations will still reach 2x pre-industrial levels sometime this century.

[kiwistonewall]

Dec 31, 2009 19:10:28 GMT glc said:

Re: the study

I'm pretty sure this has been discussed before on this blog. This has been known about for some time. However, even if the airborne proportion remains at ~45%, atmospheric CO2 concentrations will still reach 2x pre-industrial levels sometime this century.

Which is fantastic news, as it will counter the coming ice age, and increase agricultural productivity.

We can assume, IF CO2 does "warm" the Earth, that there is now something bigger overriding CO2.
So any reduction in emissions will precipitate a mini ice age.

In fact, there are some who think that Asia's invention of the paddi field 4000 years ago increased Methane & is the main reason we are not in an ice age now.

The tipping point into an ice age is very, very sensitive, and needs to be avoided at all costs.

All the drivers are toward cold. Anything that avoids that fate should be promoted.

The emitters are heroes. (Well, one day, we will affirm that!)

[stranger]

In reality, if the airborne concentration of CO2 has not increased in 160 years, it is very doubtful that the percentage that remains in the atmosphere has changed in that time period. If there is a change, it would be the other way, to faster CO2 removal from circulation since we are busily planting fast growing trees to replace the slow growing native species that were cut down in the past.

The key metric is in tonnes of atmospheric CO2 bound up by conversion to plants, and by every measure I can find that is slowly increasing.

Stranger

[wylie]

Unfortunately, the amount of CO2 being absorbed by the earth will increase with time AND the amount of CO2 that can be emitted to "counter" any new ice age will not increase. Peak Oil and Peak Coal are already upon us. Anyone spending the time to look at actual production numbers will easily see that. Unfortunately, the "BAU" projections from the IPCC assume infinite supplies of economically recoverable fossil fuels. Since the earth is not flat that is not possible.

The other undeniable fact is that the oceans are nowhere NEAR being saturated with CO2. As the atmospheric concentration rises, Henry's (or Charles') Law will ensure that the rate of dissolution of CO2 in the oceans will increase. Since there are orders of magnitude more CO2 in the oceans already and they are still orders of magnitude from being saturated, an increase in atmospheric CO2 is far more important for the rate at which CO2 dissolves than any minor increase in temperature (if there is one).

Of course, since CO2 is so important for increasing plant growth rates both on the earth's surface and in the oceans, that rate will also increase (as it has already). Personally, I cannot imagine a better result than a delay in the Ice Age, an increase in CO2 to increase plant growth rates and an increase in temperature to heat up the Northern regions of Canada, the US and Siberia and the southern regions of Chile and Argentina. It is not a coincidence that there are many times for species in a tropical rain forest than on a Tundra.

Now all we have to do is persuade the greedy politicians from messing it all up!! (a tough task)

Wylie

[glc]

In reality, if the airborne concentration of CO2 has not increased in 160 years, it is very doubtful that the percentage that remains in the atmosphere has changed in that time period.

You might have got this right but it's difficult to tell. Basically, in the pre-industrial period, CO2 concentrations were roughly stable. The amount emitted to the atmosphere was pretty much the same as the amount absorbed by the oceans and biosphere. When humans started producing CO2 from fossil fuels ~55% of the extra CO2 was absorbed and ~45% remained in the atmosphere. The concerne was that, as human CO2 production increased, the earths ability to maintain the level of absorption would decrease. But it appears that it hasn't - not to any great extent at least. It sems that about 55% gets absorbed whether we produce 1 GtC or 7 GtC.

This gives a reasonable summary of the situation:
www.worldclimatereport.com/index.php/2009/11/10/airborne-fraction-of-human-co2-emissions-constant-over-time/

[slh1234]

I can't get to the link you posted, but I have a question on this. The Mauna Loa data (which I have questioned in the past due to it's proximity to two active volcanoes), seems to indicate that atmostpheric CO2 levels have increased at least since 1959. How can the divergence between this and also the Barrows Alaska data be explained in the claim that CO2 has not increased in the last 150 years.

If you an post excerpts from the link that provide the explanation for that, I would appreciate that.