From the University of Virginia, comes yet another incomplete press release that doesn’t give the name of the paper or the DOI:
Salt marsh carbon may play role in slowing climate warming, study shows
A warming climate and rising seas will enable salt marshes to more rapidly capture and remove carbon dioxide from the atmosphere, possibly playing a role in slowing the rate of climate change, according to a new study led by a University of Virginia environmental scientist and published in the Sept. 27 issue of the journal Nature.
Carbon dioxide is the predominant so-called “greenhouse gas” that acts as sort of an atmospheric blanket, trapping the Earth’s heat. Over time, an abundance of carbon dioxide can change the global climate, according to generally accepted scientific theory. A warmer climate melts polar ice, causing sea levels to rise.
A large portion of the carbon dioxide in the atmosphere is produced by human activities, primarily the burning of fossil fuels to energize a rapidly growing world human population.
“We predict that marshes will absorb some of that carbon dioxide, and if other coastal ecosystems – such as seagrasses and mangroves – respond similarly, there might be a little less warming,” said the study’s lead author, Matt Kirwan, a research assistant professor of environmental sciences in the College of Arts & Sciences.
Salt marshes, made up primarily of grasses, are important coastal ecosystems, helping to protect shorelines from storms and providing habitat for a diverse range of wildlife, from birds to mammals, shell- and fin-fishes and mollusks. They also build up coastal elevations by trapping sediment during floods, and produce new soil from roots and decaying organic matter.
“One of the cool things about salt marshes is that they are perhaps the best example of an ecosystem that actually depends on carbon accumulation to survive climate change: The accumulation of roots in the soil builds their elevation, keeping the plants above the water,” Kirwan said.
Salt marshes store enormous quantities of carbon, essential to plant productivity, by, in essence, breathing in the atmospheric carbon and then using it to grow, flourish and increase the height of the soil. Even as the grasses die, the carbon remains trapped in the sediment. The researchers’ model predicts that under faster sea-level rise rates, salt marshes could bury up to four times as much carbon as they do now.
“Our work indicates that the value of these ecosystems in capturing atmospheric carbon might become much more important in the future, as the climate warms,” Kirwan said.
But the study also shows that marshes can survive only moderate rates of sea level rise. If seas rise too quickly, the marshes could not increase their elevations at a rate rapid enough to stay above the rising water. And if marshes were to be overcome by fast-rising seas, they no longer could provide the carbon storage capacity that otherwise would help slow climate warming and the resulting rising water.
“At fast levels of sea level rise, no realistic amount of carbon accumulation will help them survive,” Kirwan noted.
Kirwan and his co-author, Simon Mudd, a geosciences researcher at the University of Edinburgh in Scotland, used computer models to predict salt marsh growth rates under different climate change and sea-level scenarios.
The United States Geological Survey’s Global Change Research Program supported the research.
Contact: Fariss Samarrai fls4f@virginia.edu (and tell him to make complete press releases please)
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After some searching, I found the paper and the abstract:
Response of salt-marsh carbon accumulation to climate change
Matthew L. Kirwan & Simon M. Mudd
- Nature 489, 550–553 (27 September 2012) doi:10.1038/nature11440
About half of annual marine carbon burial takes place in shallow water ecosystems where geomorphic and ecological stability is driven by interactions between the flow of water, vegetation growth and sediment transport1. Although the sensitivity of terrestrial and deep marine carbon pools to climate change has been studied for decades, there is little understanding of how coastal carbon accumulation rates will change and potentially feed back on climate2, 3. Here we develop a numerical model of salt marsh evolution, informed by recent measurements of productivity and decomposition, and demonstrate that competition between mineral sediment deposition and organic-matter accumulation determines the net impact of climate change on carbon accumulation in intertidal wetlands. We find that the direct impact of warming on soil carbon accumulation rates is more subtle than the impact of warming-driven sea level rise, although the impact of warming increases with increasing rates of sea level rise. Our simulations suggest that the net impact of climate change will be to increase carbon burial rates in the first half of the twenty-first century, but that carbon–climate feedbacks are likely to diminish over time.
henrythethird says:
September 26, 2012 at 7:59 pm
“…A warmer climate melts polar ice, causing sea levels to rise…”
So, it stands to reason that if the warmer climate has given us the greatest melt of Arctic Sea Ice since the start of the satellite observations, we should also be seeing the greatest amount of sea level rise in the same time period.
The Arctic ice is floating on the ocean, so if it melts it has no impact on sea level rise. Greeland and Antarctica, being land masses covered in ice, would impact sea levels should they experience melting.
Matt says:
September 27, 2012 at 3:21 pm
The validity of isotope analysis to deferatiate natural/antro CO2 emissions presupposes that there aren’t any processes in the atmosphere that will alter the isotope balance over time. Like maybe cosmic rays for example.
Isn’t C14 supposed to be created in the atmosphere by cosmic ray bombardment? Can you rule out something similar for C13
Indeed 14C is created (in deviation of the mass balance!) in the atmosphere as result of collisions of nitrogen with cosmic ray particles. The amounts are quite low: some 12 orders of magnitude lower than 12C. It is continuously destroyed in radioactive decay, back to 14C with a half life time of about 5.7 kyr.
13C is a stable isotope and I have no knowledge of some extra creation via cosmic rays, but as it actually is over 1% of all carbon (the bulk is 12C), it is unlikely that a small increase via cosmic rays would be important.
To make a difference between the origins of CO2, one can use the 13C/12C and 14C/12C ratio, besides oxygen use:
– All inorganic carbon has a “high” 13C/12C ratio. The chosen standard, Pee Dee Belemnite (PDB) was a carbonate deposit somewhere in the US, but as that was exhausted, the new standard is a fixed ratio between 13C and 12C, called the Vienna PDB or VPDB. All other carbon sources are compared to that one and expressed in per mil to the standard. A lower per mil means a lower 13C/12C ratio. Inorganic carbon in general is around zero per mil, that is for all carbonate deposits, volcanic vents (subduction volcanoes, deep magma volcanoes are slightly lower), seawater releases, etc.
– All organic carbon has a (much) lower 13C/12C ratio: photosynthesis prefers 12CO2 above 13CO2, which makes that all historical (fossil) and new plants have a low per mil: between -14 and -40 per mil, depending of the biological processes involved.
Fossil fuels, including coal and oil are around -25 per mil, natural gas is much lower.
– Fossil fuels don’t contain measurable quantities of 14C, because too old. Recent formed wood does contain 14C, depending of the age of formation. Thus here one can make a distiction between fossil fuel burning and e.g. forest fires.
– The atmosphere was at about -6.4 per mil over the past ice ages, until some 160 years ago. The variation over the ice ages and the last interglacial was a few tenths of per mil around that value until about 1850. Since then, the 13C/12C ratio dropped to -8 per mil, completely in ratio with fossil fuel burning. At the same time, the 14C/12C ratio dropped, so that since 1870 correction tables were necessary to correct the carbon dating. That only can be from 14C depleted fossil fuels.
– The drop in 13C/12C ratio of the atmosphere can’t be from the oceans, as any substantial release of oceanic CO2 would increase the 13C/12C ratio of the atmosphere. But it could be from vegetation decay (of about 1/3rd of all land vegetation!). But there, the oxygen balance is of help: the oxygen balance shows that the whole biosphere is a net absorber of CO2, and preferably of 12CO2 and thus not the cause of the 13C/12C ratio decline, or the CO2 increase.
Thus all together, the isotope and oxygen balances are a quite firm confirmation that humans are responsible for the CO2 increase in the atmosphere…
Bart says:
September 27, 2012 at 4:49 pm
We’ve been through this all so many times before. Your arguments are invalid. They simply do not recognize the dynamic nature of the system, and how such systems are required to behave by physical and mathematical laws.
Indeed, many times… But I am curious about your answer on the revised fountain example, which is about the same dynamic behavior of what happened/happens with CO2 in the atmosphere…
And some answer how why you think that the same physical processes are responsible for the fast responses and the still not defined trend/cycle of at least 200 years…
Ferdinand Engelbeen says:
September 28, 2012 at 12:51 am
Of course,
It is continuously destroyed in radioactive decay, back to 14C
must be
It is continuously destroyed in radioactive decay, back to 14N…
richardscourtney says:
September 27, 2012 at 4:33 pm
1. The anthropogenic greenhouse gas (GHG) emissions, notably of carbon dioxide (CO2), are to some degree accumulating in the atmosphere.
and
I am certain that assumptions 1 and 3 are untrue because they are denied by empirical data.
I don’t know of any empirical data which prove that human induced CO2 is not accumulating to some degree in the atmosphere. To the contrary: the decrease in 13C/12C ratio and 14C/12C ratio proves that CO2 from fossil fuel burning does accumulate in the atmosphere…
Ferdinand Engelbeen says:
September 28, 2012 at 2:30 am
“But I am curious about your answer on the revised fountain example,…”
Again, you’ve given a static example in which the input from the well is fixed. You are begging the question. By assuming that is so, you have already fixed the outcome.
It all depends on the magnitude of the flows, and the size of the drain. In the very simplest terms possible, assuming slowly changing flows
L := k*(A + N)
L = level in the basin
A = hose input rate
N = well input rate
k = coupling factor dependent on drain
You know L and A, but you do not know k and N. That gives you one equation with two unknowns, for which there is no unique solution. When you assume you know N, then you can solve for k. But, in actual fact, there is an infinite set of possible solutions for k and N, and you have simply chosen the one which pleases you.
The terms “sequestration and emission” are inappropriately applied to CO2. The correct terms are depletion and enrichment.
bwdave says: ”The terms “sequestration and emission” are inappropriately applied to CO2. The correct terms are depletion and enrichment”
Good on ya mate, good on ya! Can you answer my question: Q: who is the clown to know that 150y ago was the best amount of CO2 for the trees and crops?!?!?!
The carbon bashers have lower knowledge / IQ, than cabbage and an oak-tree. What’s the fuss about? state of Queensland / Australia has built the first carbon geosequestration plant. 3 years ago. Not one molecule of CO2 has being buried since then, by that plant – but lots of CO2 was produced, to build it and 102 million bucks buried, to build the white elephant. CO2 is made 66% of oxygen – that oxygen is needed above the surface, not deep down.
CO2 is washed in the sea by the rain -> corals / algae collect it -> keep the carbon for themselves -> release the oxygen in the water for the fish. Part of the oceans, for big part of the year are oxygen depleted – not enough to sustain many variety of fish. 3]Oxygen in the atmosphere is a perfect insulator – on the moon, no oxygen & nitrogen = between day and night temp difference of 230C.
Bart says:
September 28, 2012 at 10:28 am
Bart, nobody says that the input of the well is static. All what is observed is that there is some variability in the level increase L and L is always less than what may be expected from the inflow of A which is increasing over time. That is all.
The discussion now is not what k and N are, which indeed can have a lot of values, but what the cause of the increase in L is. There may be values for k and N which makes that the increase is mostly from N and not from A. But there are a few problems with that, as that implies huge in/out flows and huge variations in in/out flows:
– Several indications show that the refresh rate of the basin from the natural input N is only 20% per hour.
– There is an observed difference in calcium and sodium content between the natural inflow and the additional supply. The change in composition of the water in the basin shows that about 33% of the additional supply builds up in the basin.
The first point shows that N is about 20% of total L per hour, while the second point shows that despite the relative huge refresh rate, a substantial part of the additional supply builds up in the basin. Thus N is not extremely huge, and k is not extremely small and most of the increase in L is from the additional supply…
In the case of CO2 in the atmosphere, the observed refresh rate (a.o. from the 14C bomb spike) shows that about 20% of all CO2 in the atmosphere per year (~150 GtC) is exchanged with CO2 from other reservoirs. And about 33% of all human induced CO2 still can be found in the atmosphere as a 13C/12C and 14C/12C ratio reduction.
If e.g. the human emissions (currently at 8 GtC/year) were responsible for 10% of the increase in the atmosphere (currently at 4 GtC/year), the natural supply must deliver 90% of the increase for the same k: thus some 72 GtC/year extra (worse if the human influence is less). That is 50% over the observed refresh rate. No such increase (or any increase) in refresh rate over the years is observed…
BTW, here an overview of the different “residence times” found over the years based on different (or the same) observations:
http://jennifermarohasy.com//wp-content/uploads/2009/09/Carbon-dioxide-residence-time.jpg
As far as I can tell from this mess, it doesn’t look like that the residence time shortened over the years, as would be the case if some natural source increased the throughput of CO2 in the atmosphere with some 50% or more…
The IPCC does use the “adjustment time” (but happens to confuse that with “residence time”…), the one that removes an extra amount of CO2 above equilibrium. Nothing to do with the residence time, which doesn’t change the total amount of CO2 in the atmosphere. Something a lot of sceptics have difficulty to see the difference…
Ferdinand Engelbeen says:
September 29, 2012 at 2:08 am
Ferdinand, you are handwaving and rationalizing. You are imagining you have solid information which you do not, and constraining the solution arbitrarily to suit your bias. And, it all conflicts with the simple observation that the rate of change of CO2 is proportional to the properly baselined temperature anomaly, and that relationship precludes significant human forcing. The evidence is quite clear and there really is no rational argument against it – you might as well be arguing that the sky isn’t really blue. I’ve done all I can to help you see. You will simply have to reap the rewards of your intransigence. Sayonara for now, until we meet again…
Bart says:
September 29, 2012 at 11:35 am
And, it all conflicts with the simple observation that the rate of change of CO2 is proportional to the properly baselined temperature anomaly, and that relationship precludes significant human forcing.
Bart, if you weren’t so overfocused on that completely spurious 50 years correlation (for the trend, not the year-by-year variability), you might see that your solution violates about all observational evidence…
But we see each other again, next time…