No rise in atmospheric carbon fraction over the last 150 years: University of Bristol

posted at 8:48 am on January 4, 2010 by Ed Morrissey

Science Daily reported on a new study from the University of Bristol released over the holidays that deserves to get wider attention.  In contrast to claims from anthropogenic global-warming activists, this new analysis refutes one of the key principles of carbon-driven warming:

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. …

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 thumbnail argument for AGW is this: the CO2 emitted by industrialization over the last 150 years has accumulated in the atmosphere, along with other gases such as methane, warming the globe more rapidly than otherwise would have happened.  The continuing emissions of CO2 from industrialized and developing nations will result in an exponential explosion of warming the longer it continues as the CO2 accumulates at faster and faster rates in the atmosphere, both because the previous emissions have not been absorbed and more people are emitting than ever.  Therefore, we have to control emissions just to contain the damage, and it might already be too late!

Of course, that’s why everyone flew private jets to Copenhagen last month — in order to warn about carbon emissions.

If this University of Bristol analysis is correct, CO2 hasn’t been accumulating in the atmosphere at all.  That means whatever warming we have experienced (and we have experienced warming) did not come from increased CO2 in the atmosphere.  That would explain why we have experienced a cooling cycle for the last ten to twelve years despite an increase of CO2 emissions, albeit an increase at a slower rate than before.  The new analysis completely destroys the AGW argument, because if CO2 is not accumulating in the atmosphere, it can’t be causing global warming.

No one doubts the necessity of curtailing particulate emissions into the air.  If anyone did, the Beijing Olympics and the thick & chunky smog would have removed those doubts.  Moving towards cleaner energy and renewables is a laudable goal and a necessary process.  But succumbing to AGW hysteria and destroying the very economy that could produce that type of progress is not just absurd, it’s counterproductive to the goal.

Update: I changed the title of this post to more accurately reflect what UB found – no change in the ratio of carbon dioxide in the atmosphere.  One correspondent says that it doesn’t change the fact that we’re still dumping carbon into the atmosphere, where it could cause global warming.  However, if the ratio of CO2 in the atmosphere hasn’t changed in 150 years, then the CO2 is getting reabsorbed, not remaining in the atmosphere to cause global warming.  Unless there are other agents adding oxygen and nitrogen to the air and increasing the volume of all three, then the increased CO2 isn’t staying in the air.  If CO2 accounted for 0.04% of the atmosphere in 1860 and 0.04% today, then CO2 isn’t a cause of warming — at least not now, and not over the last 150 years, as AGW hysterics claim.

Update II:  A friendlier message says this:

The amount of CO2 in the atmosphere is increasing.
The percentage of CO2 in the atmosphere is increasing.
However, the percentage of CO2 on the planet which is airborne (as opposed to dissolved in the oceans, trapped in ice, or incorporated into biomass through photosynthesis) is not increasing.  That is the meaning of airborne fraction. It doesn’t mean the fraction of the air which is CO2.  It’s an easy mistake to make, and many others have on other sites.

Why this matters:  One of the claims of the alarmists is that the oceans cannot hold any more CO2, that they are “saturated,” and therefore additional CO2 emissions will increasingly stay in the atmosphere.  This now appears to be false. It undermines the alarmists’ arguments a little, but not too much.  They will simply shift their position to:  “Well, they oceans aren’t saturated yet, but they will be soon.  And then the airborne fraction will increase dramatically.  Just you wait.”

There are a couple of problems with this.  First, AGW alarmists say that increased CO2 in the air causes global warming.  Second, I’m old enough to remember rainforest hysteria, where we were all going to asphyxiate ourselves by chopping down trees that produced O2 from CO2, as we reduced biomass.  If we’re producing larger biomass, then we’re creating more capacity to absorb CO2 and produce more oxygen (and food, too) as a result.  And that’s supposed to be bad?

Update III: Here’s the summary from Knorr, emphases mine:

Several recent studies have highlighted the possibility that the oceans and terrestrial ecosystems have started loosing 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.


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