University of Helsinki via Eurekalert
Unaccounted feedbacks from climate-induced ecosystem changes may increase future climate warming
The terrestrial biosphere regulates atmospheric composition, and hence climate. Projections of future climate changes already account for “carbon-climate feedbacks”, which means that more CO2 is released from soils in a warming climate than is taken up by plants due to photosynthesis. Climate changes will also lead to increases in the emission of CO2 and methane from wetlands, nitrous oxides from soils, volatile organic compounds from forests, and trace gases and soot from fires. All these emissions affect atmospheric chemistry, including the amount of ozone in the lower atmosphere, where it acts as a powerful greenhouse gas as well as a pollutant toxic to people and plants.
Although our understanding of other feedbacks associated with climate-induced ecosystem changes is improving, the impact of these changes is not yet accounted for in climate-change modelling. An international consortium of scientists, led by Almut Arneth from Lund University, has estimated the importance of these unaccounted “biogeochemical feedbacks” in an article that appears as Advance Online Publication on Nature Geoscience‘s website on 25 July at 1800 London time. They estimate a total additional radiative forcing by the end of the 21st century that is large enough to offset a significant proportion of the cooling due to carbon uptake by the biosphere as a result of fertilization of plant growth.
There are large uncertainties associated in these feedbacks, especially in how changes in one biogeochemical cycle will affect the other cycles, for example how changes in nitrogen cycling will affect carbon uptake. Nevertheless, as the authors point out, palaeo-environmental records show that ecosystems and trace gas emissions have responded to past climate change within decades. Contemporary observations also show that ecosystem processes respond rapidly to changes in climate and the atmospheric environment.
Thus, in addition to the carbon cycle-climate interactions that have been a major focus of modelling work in recent years, other biogeochemistry feedbacks could be at least equally important for future climate change. The authors of the Nature Geoscience article argue that it is important to include these feedbacks in the next generation of Earth system models.
This work was promoted by iLEAPS (Integrated Land Ecosystem and Atmospheric Processes), a core project of the International Geosphere-Biosphere Programme, and developed through workshops supported by the Finnish Cultural Programme.
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Journal Reference: (note the actual paper was not provided with this press release)
A. Arneth, S. P. Harrison, S. Zaehle, K. Tsigaridis, S. Menon, P. J. Bartlein, J. Feichter, A. Korhola, M. Kulmala, D. O’Donnell, G. Schurgers, S. Sorvari & T. Vesala. Terrestrial biogeochemical feedbacks in the climate system. Nature Geoscience, July 25, 2010 DOI: 10.1038/ngeo905
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Pamela Gray says:
July 26, 2010 at 2:09 pm
these IPCC scientists have already figured out what they want to say in the next report so are flooding the journal and magazine river systems with research and articles that will say what they want to say?
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puts finger to tip of nose and winks
“It could very well be “unaccounted for feedbacks” that have driven the Arctic sea ice extent summer minimum to well below even the lowest GCM predicted.”
Only in climate science is a model wrong and the people get excited about it. Hooray, the GCM’s were wrong, lets celebrate by making up more feedback scenarios to feed into our models, and tomorrow we can be wrong again!
In most fields being wrong is not a good thing…
Although our understanding of other feedbacks associated with climate-induced ecosystem changes is improving, the impact of these changes is not yet accounted for in climate-change modelling.
B*llocks!! I’ve been working in this area since 1979, and my colleagues at Univ of IL have long published articles about methane flux from wetlands etc. He’s saying that the climatologists didn’t even consider this??
Mikael Pihlstrom, at 9:06 AM, does not address the fundamental point that any system which has been stable within a few percent of activity around an equilibrium for billions of years cannot be governed by positive feedback. It must be governed by negative feedback. The Earth’s system has been repeatedly perturbed by solar changes, ice ages and warm ages, vastly higher CO2 levels, and so on, and it keeps cycling back to near the average of the last billion or so years. Only a negative feedback system can behave this way. There are no ghosts, there were no real witches in Salem, the Hale-Bopp comet did not presage the End of Days, and CAGW is not reasonable.
The idea that human input to CO2 production of about 4% of total global CO2 emissions annually is going to force the Earth’s climate into runaway positive feedback defies common sense, given Earth’s climate history. Add to that, that although CO2 has continued to rise in the last decade, temps have not….and the common sense position remains: be skeptical of CAGW.
R. Gates says:
July 26, 2010 at 11:28 am
So, in your model, the Arctic will melt completely, release 40% more C02, which will get sucked into the Antarctic.
We will witness C02 thunderstorms, and Anatarctica will get covered in x# of feet of dry ice.
I’m just following the logic, and being mindful of the opposite effect at the South Pole… currently in operation.
trbixler says:
July 26, 2010 at 7:10 am
So Dyson suggests that there are many unaccounted for feedbacks and suddenly they are found to be positive. The model is correct again. On further reading Dyson suggests get out of the air conditioned computer lab and do some measurements.
Video of Dyson saying that. Video is mightier than the pen.
For goodness sake, don’t they even know yet about Willis’ thermostat!! 😉
They continue to leave out water vapor in the atmosphere and clouds. Negative feedback has the final say. If not then heat on the earth would have already been out of control.
Ken Hall says:
July 26, 2010 at 8:38 am
“The crap will never stop, as long as there are people that are hearing what they want to hear.”
That is sad. But sadly it is true of people on ALL sides of the climate change debate. I think, myself included.
Doesn’t the data have a say? It does with me. And I don’t see anything unusual happening in climate data. Everything is continuing on the way it always has. So whether I want to be an optimists about the future, a pessimist, an agnostic, a skeptic, or what ever. It doesn’t matter. Nothing at all unusual is happening in the data. So let’s say with Monckton, “Let’s have the courage to do nothing.”
Eisenhower told us there’d be days like this:
vukcevic says:
July 26, 2010 at 9:42 am
A minor nitpick you left out the auxiliary internal power source needed to overcome losses and to ensure that signal potential at the output is greater than the potential at the input or you can only get feed forward not feedback, either positive or negative.
Ben says:
July 26, 2010 at 3:55 pm
“Only in climate science is a model wrong and the people get excited about it.”
Oh, I am so stealing that!!! 🙂
John Campbell says:
July 26, 2010 at 7:34 am
It would be interesting if the authors were to give, in the abstract of their article, some indication of the degree of uncertainty associated with their suppositions. In addition, they might indicate (also in the paper’s abstract) whether their work shows causation or only correlation.
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John, the uncertainty is uncertain, hence its confusion worse confounded. Global madness.
Graham Green says “I don’t know if this is just a coincidence but funnily enough I too have though of some things which are supported by no evidence whatsoever. I haven’t actually tried to quantify any of these things but they could be very important. Can I have some money please?”
Graham Green must have heard the story of the wildly successful clairvoyant with Alzheimer’s disease who forgot to state his/her predictions before they actually came true.
I did a bit of calculating on forest growth and came to the conclusion that fast growth species like cottonwood or eucalyptus can suck all the CO2 out of the air down to ‘starvation levels’ in very few years using only a modest percentage of the earth surface.
Pond scum (aka algae) can do it 10 times faster.
Yeah, the biosphere can change the CO2 fast. Especially to the downside.
http://chiefio.wordpress.com/2009/06/02/of-trees-volcanos-and-pond-scum/
Anyone who actually knows the photochemistry of ozone formation in the lower levels of the atmosphere knows that there is absolutely no correlation between CO2 concentration and O3 concentration whatsoever.
Projections of future climate changes already account for “carbon-climate feedbacks”, which means that more CO2 is released from soils in a warming climate than is taken up by plants due to photosynthesis.
I dispute this. The paper is behind a firewall. The abstract states calculations involved to make this statement are estimated. Soil organic matter has been increasing with increasing CO2 and precipitation. How can the estimations explain that little factoid?
The Great Fog Bank alone must be a substantial negative feedback component which is not accounted for in the GCMs. Add to it, the lesser siblings such as the ones off of NW Africa, SW Africa and S. America. Oh, and the annual peak of such advective stratus formations only lags the peak sun angle by one or two months at most.
I quote from their abstract: “Total positive radiative forcings resulting from feedbacks between the terrestrial biosphere and the atmosphere are estimated to reach up to 0.9 or 1.5 W m−2 K−1 towards the end of the twenty-first century, depending on the extent to which interactions with the nitrogen cycle stimulate or limit carbon sequestration.” Apparently they are still on the carbon trail – CO2 done it! Well CO2 did not do it, and cannot do it, and neither can any of the other gases that absorb in the infrared. That is because the infrared absorption band of the atmosphere is saturated and no further addition of greenhouse gases that absorb in the infrared can change the already-existing greenhouse effect. So how do I know this and they are ignorant of this? Simple – Ferenc Miskolczy has used the NOAA database of weather balloon observations to show that the global average annual infrared optical thickness of the atmosphere has been unchanged for 61 years and has a value of 1.87. His article appears in Energy & Environment, volume 21, No. 4, page 243. And what does this mean? It means that constant addition of carbon dioxide (and those other gases) to the atmosphere has not changed the transparency of the atmosphere in the infrared one whit or the optical thickness would have increased. And it didn’t, despite of what Svante Arrhenius said. Problem is that Svante did not have modern technology and while the global warming advocates do they simply don’t know what to do with it. It was one man’s persistence that showed us what NOAA’s multi-year database which was gathering dust really contains. I have looked at global temperature data from satellites and have come to the conclusion that the “anthropogenic global warming” has never been observed. No wonder, since Miskolczy’s result means that it is physically impossible.
RE: k winterkorn: (July 26, 2010 at 8:00 am) “1. It is the ‘+’ sign in the diagram that indicates these are not scientists, in the best understanding of the term. The sign should either be a ‘?’ or ‘+/-‘, but that would probably interfere with future funding of their research.”
Actually this is a rather standard textbook illustration that applies to feedback and control systems. The ‘+/-‘ aspect of the feedback is determined by the factor ‘B’ which can be a positive or negative real number or a complex non-linear transfer function. The ‘+’ simply denotes the merging of the direct input forcing and some, perhaps complicated, result of the system output. In the general case, I believe the actual merging process is also undefined.
In the real world we may have a vast array interacting networks of this type.
As for unaccounted feedbacks, I guess we can speculate all day on things we do not know. I am not sure that speculation should rise to the level of a scientific paper.
Anything’s possible!
Today’s best model will look like the first cave painting in fifty thousand years. Ask me how I know..