From the Pacific Northwest National Laboratory:
Soils release more carbon dioxide as globe warms
COLLEGE PARK, Md. – Twenty years of field studies reveal that as the Earth has gotten warmer, plants and microbes in the soil have given off more carbon dioxide. So-called soil respiration has increased about one-tenth of 1 percent per year since 1989, according to an analysis of past studies in today’s issue of Nature.
The scientists also calculated the total amount of carbon dioxide flowing from soils, which is about 10-15 percent higher than previous measurements. That number — about 98 petagrams of carbon a year (or 98 billion metric tons) — will help scientists build a better overall model of how carbon in its many forms cycles throughout the Earth. Understanding soil respiration is central to understanding how the global carbon cycle affects climate.
“There’s a big pulse of carbon dioxide coming off of the surface of the soil everywhere in the world,” said ecologist Ben Bond-Lamberty of the Department of Energy’s Pacific Northwest National Laboratory. “We weren’t sure if we’d be able to measure it going into this analysis, but we did find a response to temperature.”
The increase in carbon dioxide given off by soils — about 0.1 petagram (100 million metric tons) per year since 1989 — won’t contribute to the greenhouse effect unless it comes from carbon that had been locked away out of the system for a long time, such as in Arctic tundra. This analysis could not distinguish whether the carbon was coming from old stores or from vegetation growing faster due to a warmer climate. But other lines of evidence suggest warming is unlocking old carbon, said Bond-Lamberty, so it will be important to determine the sources of extra carbon.
The Opposite of Photosynthesis
Plants are famous for photosynthesis, the process that stores energy in sugars built from carbon dioxide and water. Photosynthesis produces the oxygen we breathe as a byproduct. But plants also use oxygen and release carbon dioxide in the same manner that people and animals do. Soil respiration includes carbon dioxide from both plants and soil microbes, and is a major component of the global carbon cycle.
Theoretically, the biochemical reactions that plants and soil microbes engage in to produce carbon dioxide suggest that higher temperatures should result in more carbon dioxide being released. But unlike the amount of sunlight reaching Earth, soil respiration can’t be measured from space and can’t yet be simulated effectively with computer models.
So, the researchers turned to previous studies to see if they could quantify changes in global soil respiration. PNNL’s Bond-Lamberty and his colleague Allison Thomson, working at the Joint Global Change Research Institute in College Park, Md., examined 439 soil respiration studies published between 1989 and 2008.
They compiled data about how much carbon dioxide has leaked from plants and microbes in soil in an openly available database. To maintain consistency, they selected only data that scientists collected via the now-standard methods of gas chromatography and infrared gas analysis. The duo compared 1,434 soil carbon data points from the studies with temperature and precipitation data in the geographic regions from other climate research databases.
After subjecting their comparisons to statistical analysis, the researchers found that the total amount of carbon dioxide being emitted from soil in 2008 was more than in 1989. In addition, the rise in global temperatures correlated with the rise in global carbon flux. However, they did not find a similar relation between precipitation and carbon.
Zooming In
Previous climate change research shows that Arctic zones have a lot more carbon locked away than other regions. Using the complete set of data collected from the studies, the team estimated that the carbon released in northern — also called boreal — and Arctic regions rose by about 7 percent; in temperate regions by about 2 percent; and in tropical regions by about 3 percent, showing a trend consistent with other work.
The researchers wanted to know if their data could provide more detailed information about each region. So they broke down the complete data set by regional climates and re-examined the smaller groups of data using different statistical methods. The regional data from the temperate and tropical climates produced results consistent with other results, such as more carbon being released at higher temperatures, but the boreal-Arctic climate data did not. In addition, removing only 10 percent of the boreal-Arctic data points was enough to invalidate the statistical significance of the boreal-Arctic result. Together, the results support the idea that more boreal data on regional climates is needed to reach statistical relevance.
“We identified an area where we need to do more work,” said Thomson.
The authors designed the database so that other researchers could contribute to it. The paper describing the database can be found online in Biogeosciences.
Reference: Bond-Lamberty and Thomson, 2010. Temperature-associated increases in the global soil respiration record, Nature March 25, 2009, doi:10.1038/nature08930.
This research was supported by Pacific Northwest National Laboratory and by the Office of Biological and Environmental Research within the Department of Energy’s Office of Science.
Wren (20:08:58) :
If you get the right answer by faulty method, forget it. Throw that answer in the trash. We want right methods, not right answers.
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A broken clock is precisely right twice a day. I can see you are the type that would feature this clock as a fine working machine even though it is broken. After all, getting something right, even with a wrong method, is ok.
But really, we need to toss out the broken clock and the broken ‘global warming’ computer climate models, hypothesis’, and data handling procedures. No more ‘trick’ from Mike.
It would be a cleaner world then.
And isn’t that what global warming is all about—a cleaner world?
Wren (20:32:40) :
pigprogress is a far more accurate source of information than the Telegraph.
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I know an even more accurate source: WattsUpWithThat
If Tommy Gold’s ideas merit attention, then CH4 and CO2 emmisions from the solid earth from the subterranean biosphere represent another “unfactored” forcing in the climate system.
Folks,
We humans are a life form that oxidises carbon to live.
To then penalise carbon consumption for some maligned political goal is nothing other than extremist misanthropical belief. They are simply, to coin a coarse term, brain-[snipped]. (Or dead).
[Sorry Louis, we’re ‘Mericans here, started by Puritans (who escaped from the Roundheads’ rule). Some folks would be offended by dropping the f-bomb. Protecting our innocent womenfolk & all. ☺ ~dbs]
davidmhoffer (19:03:49) :
While this makes sense on land, does it not rain over the ocean too?
I skimmed the paper. My question relates to ocean circulation. Various ocean currents move large amounts of water from warm to cold and vice versa. The paper seems to treat the oceans as static except for upwelling etc. Would not the ocean currents be constantly moving co2 laden cold water to warm, releasing CO2, and co2 defficient warm water toward the poles, where its capacity to absorb increases as it cools.
Even with heavy rain (100 l/m2 = 10 cm water increase by rain), over the oceans, that will mix in quite rapidely in the upper ocean layer, which is about 100 m thick (in average). Thus the local/regional mixing in is about 0.1% of the upper ocean volume. That hardly changes the composition and thus the pCO2 of the surface seawater, which is the dominant factor for CO2 releases/uptake. Depending where it rains, the CO2 dissolved in the drops will be released immediately or retained and added to the sink rate.
Moreover, raindrops are formed at hundreds to thousands meter altitude, warming up (thus loosing CO2) while falling down. There is little difference in CO2 levels between altitudes over the oceans…
The main CO2 flow is via the deep oceans: huge dissolving in the NE Atlantic, upwelling in the equatorial Pacific (some 1,000 years later)… Surface flows are in constant connection with the atmosphere and act as source/sink at the place where they are, based on temperature, DIC (dissolved inorganic carbon) content, pH, biolife,… It doesn’t make much difference if the ocean surfaces are static or dynamic transporting CO2 over the latitudes, as most of the exchanges with the atmosphere are regionally controlled, mainly by temperature and up/downwelling from/to the deep oceans.
Wren said:
“COULD WE RUN OUT OF GATES?”
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I’ve done my part to make sure that doesn’t happen, adding two little carbon footprints in the process…
Wouldn’t this same process have happened during the MGWP? (I renamed MWP to MGWP – Medieval Global Warming Period)
Is ice core sampling capable of verification one way or the other?
And… just restating the obvious… it remains meaningless at a fundamental level if no credible evidence can be produced to prove that CO2 level has any measurable impact on earth’s climate.
Mike M (08:53:08) :
Wouldn’t this same process have happened during the MGWP? (I renamed MWP to MGWP – Medieval Global Warming Period)
Is ice core sampling capable of verification one way or the other?
Indeed there is a small drop of CO2 levels from the MWP to the LIA of about 6 ppmv. If we may assume that the temperature difference was about 0.8 C (NOT derived from Mann’s HS), then the difference is about 8 ppmv/C. That is similar to changes found during glacials-interglacials over the past 420,000 years.
That includes all processes, including ocean absorption/releases, forest/ice cap area changes, plant growth and decay, soil respiration…
Indeed there is a small drop of CO2 levels from the MWP to the LIA of about 6 ppmv. If we may assume that the temperature difference was about 0.8 C (NOT derived from Mann’s HS), then the difference is about 8 ppmv/C>>
This would seem reasonable provided that the NH and SH change temperature in concert with each other. The current trend of the last few years shows temperature in both hemisphere’s rising, but prior to that the temperature record shows the SH following a different trend in opposition to the NH and thus having a tendency to cancel each other out to some extent. If they were in concert with each other in MWP/LIA then 8 ppm/C makes sense, but if they were in opposition to each other then it would more correctly be X-Y=8ppm/C ?
davidmhoffer (10:32:55) :
The 8 ppmv/C indeed is only for global temperatures (during ice ages/interglacials in fact for SH SST, as the dD or D18O of the inland ice cores is mostly influenced by SH ocean temperatures). For the MWP-LIA transition, that depends of where the proxies were sampled. In the case of the Moberg (and Esper) reconstructions, the bulk of the samples is in the NH, with some from the Carribean and a few in the SH…
For the modern variability of CO2 increase around the trend, there is a good correlation with global SST (and/or satellite trends). The 1992 Pinatubo temperature dip and 1998 El Niño rise of temperature shows some 1 month lag for CO2 levels and 4 ppmv/C change.
I suppose that if NH and SH sea surface temperatures were going in exact opposite directions that the CO2 levels wouldn’t change…
Ferdinand Engelbeen
I suppose that if NH and SH sea surface temperatures were going in exact opposite directions that the CO2 levels wouldn’t change…>>
If I use NASA/GISS broken down by latitude and focus on the 44N to 90N, and 44S to 90S (too short a time period to be conclusive of course, and far arctic weather station is iffy too…) I can observe the following temperature anomalies:
1901 – 1923 NH- SH-
1923 – 1970 NH+ SH-
1970 – 1979 NH- SH+
1979 – 2009 NH+ SH+
So, if we focus on those portions of the world that show the most temperature variation (and hence the most change in CO2 absorbtion) we get both hemispheres below normal for 1/4 the record, both above normal for 1/4 the record, and in opposite directions for half the record. Perhaps this nets to zero on a millenial scale, but I think this shows why I question calculating temperature sensitivity for CO2 on a global temperature calculation. In the event that we could get rid of all the noise in the system and only look at temperature and ocean obsorption, if we used global temperatures only, we would get one value for 1923 – 1979 and a completely different (much higher) value for the timeline before and after.
davidmhoffer (14:20:50) :
I don’t think that the NH/SH behaviour makes much difference for the temperature/CO2 ratio. Pieter Tans of NOAA used a response function for temperature (and precipitation) changes over the past 50 years, which explains about 2/3rd of the observed CO2 rate of change variability. See the second halve of his presentation at the festivities for 50 years Mauna Loa CO2 observations:
http://esrl.noaa.gov/gmd/co2conference/pdfs/tans.pdf
Thus that covers the data over three periods with different behaviour of the NH and SH…
Ferdinand,
On the 8 ppm/C, I know there was a recent paper that was close to this number and I’ve seen it quoted before but I get about 15 ppm/C for the ice ages.
CO2 changes from 287 ppm at the height of the last Eemian interglacial (temp +2.0C) to 185 ppm at the height of the last ice age (temp -5.0C) or about 15 ppm/C.
If one is using the deep ocean as the final arbitrator of the ppm/C ration, it would be much higher since deep ocean temperatures probably only changed by about 2C or 3C through the glacial cycles.
Ferdinand Engelbeen
Thus that covers the data over three periods with different behaviour of the NH and SH…>>
I made the point about temp anomalies being +ve or -ve to explain, but I should have gone into more detail. It’s not just a function of which hemisphere is up and which is down, it is also a function of which way each is trending. On a seasonal scale, they obviously trend in opposite directions.
On GISS, they both trend up from about 1967 on. Prior to 1934 however, the NH trend was up and the SH trend was down going back to 1880. The part in between is wishy washy. So the last 50 years of data would not demonstrate what I’m trying so poorly to articulate.
Oh Noes, Mother Earth is killing herself. Looks like soil and all the natural good things in it needs to be listed as being hazardous to the environment and have the EPA ban it all and tax it all out of existence.
Bill Illis (07:39:43) :
On the 8 ppm/C, I know there was a recent paper that was close to this number and I’ve seen it quoted before but I get about 15 ppm/C for the ice ages.
I have seen similar figures somewhere between 8 and 12 ppmv/C, depending of what you take as proxy for temperature. Further the 8 ppmv/C is only releated to the SH ocean temperature, as that is what influences the dD and d18O in the high altitude ice cores of Antarctica. It may be that the temperature differences in the NH were more pronounced with more land ice during glacials and higher land temperatures/forests area during interglacials. On the other hand, some 8 ppmv/C was also found for the MWP-LIA difference, which was mainly based on NH proxies over land (Moberg, Esper)…
Anyway, it is somewhere around 10 ppmv/C, including all slow changes of ice caps and forests growing and waning, ocean currents,…