Unaccounted feedbacks from climate-induced ecosystem changes may increase future climate warming

Jul 25, 2010

In addition to the carbon cycle-climate interactions that have been a major focus of modeling 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.

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 . Climate changes will also lead to increases in the emission of CO2 and methane from wetlands, nitrous oxides from soils, from forests, and trace gases and from fires. All these emissions affect , including the amount of ozone in the lower atmosphere, where it acts as a powerful 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 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 .

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.

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Provided by University of Helsinki

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omatumr
1.5 / 5 (8) Jul 25, 2010
Since the sales pitch for the carbon cycle-climate interactions didn't fly, and Al Gore is in disgrace, the authors want to add "other biogeochemistry feedbacks" in the next generation of Earth system models !

How about admitting that the climate models are worse than useless?

That's my opinion of these fear mongering tactics.

Oliver K. Manuel

Bob_Kob
1.6 / 5 (7) Jul 26, 2010
There is no doubt vested interests into global warming propaganda Oliver. Its beyond just incomplete models or errors.
Rsonnist
2.3 / 5 (6) Jul 26, 2010
"may increase", "large uncertainties", "could be"
vanderMerwe
1 / 5 (5) Jul 26, 2010
Actually, it looks like to me the "climate warming" has become nothing more than a throwaway line and that the climate modelers are just getting on with trying to refine their large, unwieldy simulation models. :-)
Going
4.9 / 5 (7) Jul 26, 2010
An intelligent article that deserves better comment than the usual crowd of skeptics and conspiracy theorists. Of course the Earths atmosphere is influenced by more than just the carbon cycle. Tentative language is to be expected at this stage of our understanding.
thermodynamics
5 / 5 (3) Jul 26, 2010
Going: Very good comment. You are right that the right approach should be tentative at this point. One of the foundation observations of the conspiracy theorists is that (by their short-term calculations) the slope of the temperature curve is downward (we are moving into an ice age). Of course, this year is stacking up to be very warm and the arctic ice caps are on their way to being near the record low of 2007. Most of us know that will not have much influence on the uncertainty in long term estimations - but it should knock the wind out of the sails of the: "it is cooling" brigade. Let's see how the rest of the year goes and not confuse one year of data with a trend - but it is something that has to be perplexing to those looking for a steady march toward "ice-ball Earth."
marjon
1 / 5 (5) Jul 26, 2010
Bottom line is no one really knows all the factors that affect climate, which contradicts the AGWites who claim certain knowledge.
thermodynamics
5 / 5 (3) Jul 26, 2010
Bottom line is no one really knows all the factors that affect climate, which contradicts the AGWites who claim certain knowledge.


Marjon: Most of the scientific community (in all disciplines) carefully estimate their uncertainty. It is only when it gets to the popular press and politicians that uncertainty goes away. This is true in everything from high-energy physics to the biological sciences and is certainly true for climatology. Take a look at the journals and you will see the uncertainties taken into account (as they should be). I think a great example is the famous "hockey stick." The article was titled "Northern Hemisphere temperatures during the past millennium: inferences, uncertainties, and limitations" It seems the uncertainty part disappeared when the popular press got a hold of it and now all the skeptics hang onto is their "revelation" that there is uncertainty. Duh!
marjon
1 / 5 (3) Jul 26, 2010
Bottom line is no one really knows all the factors that affect climate, which contradicts the AGWites who claim certain knowledge.


Marjon: Most of the scientific community (in all disciplines) carefully estimate their uncertainty. It is only when it gets to the popular press and politicians that uncertainty goes away. This is true in everything from high-energy physics to the biological sciences and is certainly true for climatology. Take a look at the journals and you will see the uncertainties taken into account (as they should be). I think a great example is the famous "hockey stick." The article was titled "Northern Hemisphere temperatures during the past millennium: inferences, uncertainties, and limitations" It seems the uncertainty part disappeared when the popular press got a hold of it and now all the skeptics hang onto is their "revelation" that there is uncertainty. Duh!

IPCC is 'popular press'?

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