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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If I’m allowed another comment, I have some questions about this paper.
The caption of Fig 1 says the dotted line refers to a constant AF of 46%. The text says it is 43%. Which is it?
He then goes on to try statistical fits, with terms for data uncertainty and effects of El Nino and volcanoes. In Fig 1, the simple model looks like it fits the way it does because of the big dip around 1990, which presumably is due to Mt. Pinatubo(?). If it weren’t for that big dip, then the fit might have been different. This makes the volcanic term interesting; I wish he had graphically shown the results where the volcanic term is included. I wonder if this is the best way to account for volcanoes.
The main contribution of the paper seems to be that the slight and barely significant trend found in Canadell (2007) is reduced if one allows for uncertainty in the data. That, and he adds in ice core data, which has higher uncertainty but is nice to look at. I’m not sure I’d call that a bombshell.
D. King (10:47:38) :
Ferdinand Engelbeen (00:08:18) :
Thanks so much for the link.
As a young engineer I had measured many different systems. What
I have found over time, is that an increase in one element of an open
system, rarely results in a linear increase of that element. In other
words, atmospheric CO2 increases are too linear. I don’t trust them.
CO2 levels, while many natural processes are far from linear, show a surprisingly linear reaction (about 8 ppmv/k) to temperature over the past 400,000 years (recently expanded to 800,000 years):
http://www.ferdinand-engelbeen.be/klimaat/klim_img/Vostok_trends.gif
That is clear for the current variability around the upgoing trend too (about 4 ppmv/K). Thus CO2 reacts quite linear to temperature.
The reaction of CO2 levels in the atmosphere to the addition of human CO2 is almost as if the whole CO2 cycle acts as a simple first order dynamic process: it is possible to emulate the increase in the atmosphere (and upper oceans), including the d13C changes, with such a behaviour.
The CO2 measurements are what they are, despite what Derek thinks about them. I have responded to his objections on 5-6 blogs, but did miss the one you mention. But see my replies e.g. at:
http://www.greenworldtrust.org.uk/Forum/phpBB2/viewtopic.php?t=102&postdays=0&postorder=asc&start=0
But he seems to be unconvincible…
Fred H. Haynie (12:34:28) :
I read and bookmarked your presentation. Thanks.
Chris
Norfolk, VA, USA
At these temperatures the oceans are, obviously, not net-out gassers. They came close to being net-neutral in 1998 when the CO2 accumulation in the atmosphere reached something like 3.75 ppm (assuming we’ve been putting out about 4 ppm.
It’s obvious the “fraction” changes with temperature.
Fred H Haynie,
re your
“My analysis of CO2 isotope data shows that about two thirds of atmospheric CO2 is going through an inorganic cycle and about one third through the biosphere(which includes fossil fuels).”
Just a speculation that there might be a hidden inorganic cycle. Seawater percolates through the hundreds of thousands of midocean hydrothermal vents. As water goes supercrititcal at these extremes of temperature and pressures, maybe the dissolved Co2 and the water in the vents combine to produce methane hydrates.
( PS congratulations on your excellent presentation slides )
4 billion (06:06:24) :
Geoff Sharp (05:08:05) :
The only way to answer that question is to show me a graph of ocean PH levels over the last 50 years?
————————————
What is the doubt about Ocean acidification? it is simple chemistry.
CO2 + H2O –> H2CO3
The Oceans are absorbing more CO2, nobody disputes that, as it absorbs CO2 the simple reaction described above occurs, simple chemistry. So it shouldn’t be any surprise.
Need the graph, not the chemistry lesson. Its a mighty big ocean out there.
Clearly somebody needs to find these dissident scientists and explain to them that *the science is settled* so they should just STOP this new research.
Alas, my great worry with AGW is that when the house of cards finally crumbles that the proponents longest lasting contribution will have been to seriously damage the credibility of science in the public mind for at least two generations afterwards. And that is dangerous and even tragic.
I hope that the forces that got together to knock over the house of cards will make a point of pointing proudly and often at those scientists who weren’t taken in and provided invaluable contributions to the eventual correct result.
Let me see if I understand this correctly. We have been absorbing CO2 within natural sinks for decades and now we are absorbing more than ever. Logically one would think that CO2 sinks should be filling up now instead of increasing in capacity.
I see the warmist want to ignore this logical problem. Not surprising. Just think if the CO2 sinks had absorbed exactly as much CO2 30-40 years ago as they do today, the CO2 would have fallen rather than increased.
The only way this could happen is the overall CO2 is governed by feedbacks that keep the amount in the atmosphere relatively stable. Clearly, biomass represents one negative feedback and there are likely many more that we understand no better than temperature feedbacks. Until the models can include these kind of factors they will be of little or no use in global climate studies.
Fred H. Haynie (12:34:28) :
My analysis of CO2 isotope data shows that about two thirds of atmospheric CO2 is going through an inorganic cycle and about one third through the biosphere(which includes fossil fuels). http://www.kidswincom.net/climate.pdf
Indeed, this is roughly right, but the source of the inorganic cycle is largely known: the oceans. These are seasonal (for the mid-latitudes) and permanent sources (for the tropics) and sinks (for the polar oceans). If we take into account the different in/out flows (deduced from oxygen and d13C measurements), the oceans are good for 90 GtC exchange with the atmosphere (with about 2 GtC more sink than source) over a year and the biosphere is good for 50 GtC exchange (with about 1.4 GtC more sink than source). The remainder of the emissions accumulating in the atmosphere…
I notice our BBC in the UK has somehow overlooked this important research, nothing on their news site. I wonder why?
Fred H. Haynie (12:34:28),
I just finished reading your link. You have a great ability to explain the situation clearly. I learned a lot, and I’m bookmarking it in my CO2 folder. Thanks for posting it.
Ferdinand,
Some very interesting comments in your greenworldtrust link. It made me wonder how the “350” mob would react if they knew that CO2 concentrations in depressions in the forest floor at night can reach 1000ppm. Even the ASHREA standard is “no more than 700 ppm above the outdoor air concentration”, with typical office levels in the range of 600-800ppm.
I could appreciate greenies avoiding work by staying out of offices to avoid those dangerous CO2 levels but I wonder how they would react to having to stay out of forests ?
Carrot Eater is right. No models predict a major decrease in carbon sink absorptivity… YET. While a few studies found a minor increase in the AT in the last couple of years, there was much uncertainty. So this study adds nothing new, makes no claims about future AT, and has no bearing on climate models.
Anyone who believes this study disproves global warming is making the logical fallacy of extrapolating past trends into the future. Like bankers who predicted that housing prices would never decline, the readers of this site are making the illogical extrapolation that just because the AT has not increased YET, it NEVER will.
The studies I reference come from RealClimate, and to preempt the RC bashing, remember:
1. The RealClimate post comes from 2 years ago before the Knorr study was published, so it cannot be a “biased” rebuttal to a skeptic argument.
2. The conclusions of past studies are simply factual claims of what those studies said, so even if RC is biased, that bias would have no affect on the accuracy of these statements. Just because RC says the sky is blue does not mean that it is green.
http://www.realclimate.org/index.php/archives/2007/11/is-the-ocean-carbon-sink-sinking/
Fred H. Haynie (12:34:28) :
May I disagree with your take of CO2 in ice cores? For the highest resolution ice cores at Law Dome (2 cores with 1.5 m ice equivalent snow accumulation per year), the average resolution is 8 years over the past 150 years. The third core with a lower accumulation has a 40 year resolution over 1,000 years. No clathrate formation found after relaxation. The CO2 levels in the three ice cores and still open bubbles of firn at closing depth were the same and there is a 20 year overlap (1960-1980 between the ice core / firn data and the South Pole direct measurements. All within the ice core accuracy (1 sigma = 1.2 ppmv). See:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/law_dome_sp_co2.jpg and
http://www.ferdinand-engelbeen.be/klimaat/klim_img/law_dome_1000yr.jpg
From Etheridge e.a. at:
http://www.agu.org/pubs/crossref/1996/95JD03410.shtml
Thus clathrate (de)formation is not a cause of the lower CO2 levels found for centuries ago.
All ice cores with overlapping gas ages, but complete different circumstances (temperature, dust inclusions, accumulation rate) show the same CO2 levels within 5 ppmv. Thus there is little doubt that CO2 levels found in different ice cores represent the true atmosphere of the past, be it increasingly smoothed at decreasing resolution for extending time periods. See:
antarctic_cores_001kyr_large.jpg
Sea surface temperature is NOT the cause of the recent rise. Even over tenthousands of years sustained increases/decreases during glacials-interglacials is only good for 8 ppmv/K change. Thus the global increase of about 1 K since the LIA is only responsible for 8 ppmv in CO2 level, far from the 100+ ppmv measured…
The last link to the ice cores graph must be:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/antarctic_cores_001kyr_large.jpg
Lucy Skywalker and others,
There seems to be confusion over the size Man’s contribution to CO2 – people don’t understand how Man can be responsible for all of the increase in CO2, even though our emissions constitute 2-3% of natural emissions. This results from a misunderstanding of a basic concept called “stocks and flows.” (Don’t worry – a study found that even most MIT students don’t get this concept intuitively, so it’s easy to see how people get confused). Here’s the analogy:
Imagine a bathtub in which the faucet is turned on and the drain is open, and water is entering the tub from the faucet at the same rate it is draining out of it. The tub is in equilibrium; water is entering and exiting the tub at the same rate (the “flow”), so the overall level of water in the tub (the “stock”) does not change. This is like the natural carbon cycle – in equilibrium, CO2 enters and exits the biosphere at the same rate, so the overall level in the atmosphere doesn’t change.
Back to the tub – now imagine that you add a second faucet pouring water into the tub, but only 2% as much as the original faucet. Still, because there is now slightly more water entering the tub as draining out of it, the water level slowly increases. This is like the manmade contribution to CO2 emissions: even though ours are only 2-3% of the total, that 2-3% throws the system out of balance.
So anyone who claims that man’s contributions to CO2 are minor is making a basic, if easy to make error in basic quantitative reasoning. Hope this is helpful.
Rob (12:26:32
A few UK locations:
http://img689.imageshack.us/img689/188/ukislandspaghetti.jpg
Ferdinand Engelbeen (23:58:01) :
“Despite the fact that many CO2 releases and absorptions in the natural world are quite non-linear, nature as a whole acts and reacts like a simple first order linear process on disturbances, be it temperature or human emissions.”
Allow me to run with that a little. Let the atmospheric level of CO2 be C, and its rate of change Cdot. Our model is:
Cdot = -C/tau + u + delta_u
where tau is the time constant, u is the underlying rate of natural emission, which I will assume is constant, and delta_u is manmade. delta_u has a form which, since 1950, has been more or less linear, but as of today is less than 0.03*u (3% of the natural emission rate, some say it is 1% or less). We may thus bound the current increase via
Cdot <= -C/tau + (1.03)*u
In the steady state, the increase in C should then be <= 3% of its natural level. However, the increase in C has been much greater than that. What are the possibilities?
A) an amplifying positive feedback – but there is no reason such a feedback should have been inactive until the onset of industrialization, the system is still linear, and the steady state proportionality does not change
B) the system responds to the rate of change of delta_u, i.e., has an amplifying zero, as well as the absolute value
Cdot = -C/tau + u + delta_u + K*d/dt(delta_u)
I can't think of any particular physical mechanism for this, but maybe others can. In any case, the contribution from the derivative term is bounded, and the contribution from the (slowly) linearly increasing delta_u is… slowly increasing.
C) the system has an integral term
Cdot = -C/tau – alpha*intg(C) + u + delta_u
with this value of tau actually larger than before, and previously misidentified. In this paradigm, we would merely be observing the overshoot, and the steady state concentration will settle out to a limit even if we keep increasing emissions linearly.
How might an integral term come about? Let's say plant life increases proportional to C:
Pdot = beta*C
for some constant beta. Then, CO2 is partially removed in proportion to how much plant life there is.
Cdot = -C/tau – alpha*P + u + delta_u
Seems reasonable. I'm not claiming in any way this is what is happening. I’m just saying, if you assume you can model CO2 level as a linear system, these are the simplest and most obvious options, and the last one seems the most reasonable. It will be interesting to see if CO2 starts to come down in the future. It almost looks like it is starting to in the plot at the top.
Wag,
The idea that oceans and air have been in some sort of equilibrium that should tend to maintain a semi constant air concentration is a major flaw in the models. The oceans as both sources and sinks are constantly changing their rates of emissions and absorption depending on the rate and direction of SST changes. The absorbtion in clouds and fog moderates the swings in atmospheric concentrations.
Of course, the problem with the integral feedback is that, without industrialization, C would have gone back to zero. Lucky we started burning stuff when we did!
OK, ok, we can kluge that up a little. Let
Pdot = beta*(C-C_0)
where C_0 is the “natural” level of C.
This is all fun, but the real point I want to make is, if we accept the data as presented, the increase in CO2 levels relative to the increase in emissions does not add up in a linear systems model, unless there are additional factors which, I think, generally would tend to mitigate future buildup.
WAG (15:15:31),
You continue to be unconvincing. It is clear that your mind is made up. But to clarify the difference for others between climate alarmists and scientific skeptics, the following sums up the current situation:
Those pushing the hypothesis claiming that human emitted CO2 will cause catastrophic runaway global warming [AKA: CO2=CAGW] must convincingly demonstrate that hypothesis. So far, they have failed.
Skeptics, on the other hand, are not saying that CO2 has zero effect on temperature, nor are they saying that global warming is not occurring. Yet the alarmists mendaciously try to frame the argument that way.
All that scientific skeptics are saying is: make a convincing case that your CO2=CAGW hypothesis explains observed reality better than the long accepted theory of natural climate variability. But to make a convincing case, transparency and full cooperation is required.
It is the ethical responsibility of those putting forth a new, untested hypothesis to provide strong empirical evidence that withstands falsification. And ‘evidence’ means the raw data and how it was acquired, not the output from programmed computer climate models, or a dozen cherry-picked trees out of literally millions. In order to falsify a hypothesis, those claiming it must fully and openly cooperate with requests for their raw data and methodologies. But they do not.
The fact that the promoters of the CO2=CAGW hypothesis generally refuse to cooperate with skeptical scientists [which is the only honest kind of scientist] makes falsification extremely difficult; methodologies must be reverse engineered, a very painstaking process. In effect, the CO2=CAGW promoters are saying, “Trust us.”
But that is not how the Scientific Method works. Stonewalling requests for information makes the climate alarmists’ case highly suspect. No true scientific skeptic will accept that kind of an answer.
Furthermore, skeptics have nothing to prove. This isn’t a “my idea versus your idea” debate. The believers in the CO2=CAGW hypothesis have the burden of convincing everyone — not just their particular clique — that CO2 will cause CAGW. Climate alarmists will never convince scientific skeptics, unless/until they lay out all of their information transparently, for everyone to see.
But rather than being honest, cooperative, and and upfront about their claims, climate alarmists have been devious, deliberately withholding the information necessary for experimental replication and falsification of their claimed results. By hiding their raw data and/or methodologies, climate alarmists convince everyone else that they are hiding information because it would lead to falsification of their hypothesis.
It may be true that a minor trace gas can cause runaway global warming and climate catastrophe. But no skeptic is going to be convinced until all the requested information is provided. Until then, the climate alarmists’ case fails.
WAG (15:15:31) :
Let me see if I got this right.
Rub a dub dub…too much CO2 in the tub.
WAG, that link to real climate is actually very helpful to put this paper in context.
In short, this new paper has little importance, because it isn’t saying anything new; it just disputes the finding of Canadell (2007). Nobody thought the AF would have been increasing much over that time period; if anything the models with coupled carbon cycles actually have a slight decrease in AF over that time period.
Press release overkill.
A lot of the comments seem to be revolving around the Mauna Loa CO2 data. Are there any other CO2 time histories to compare Mauna Loa against? It would seem putting so much weight on a sensor so close to a active volcano, might just give some questionable data.
J. Bob (16:50:19) :
Yes.
You would think the Mauna Loa sensors would be jumping
all over the place.
http://www.ferdinand-engelbeen.be/klimaat/klim_img/co2_trends.jpg