Thursday, February 21, 2013

New paper finds 'much lower risk' to Amazon from climate change

A paper published today in Nature finds "a much lower risk of Amazon forest dieback under CO2-induced climate change if CO2 fertilization effects are as large as suggested by current models." The paper adds to other recent papers demonstrating the Amazon is resilient to climate change due to CO2 fertilization, and that Amazon trees will tolerate IPCC projected temperature in the year 2100.


Sensitivity of tropical carbon to climate change constrained by carbon dioxide variability


Nature
 
494,
 
341–344
 
(21 February 2013)
 
doi:10.1038/nature11882
Received
 
Accepted
 
Published online
 
The release of carbon from tropical forests may exacerbate future climate change1, but the magnitude of the effect in climate models remains uncertain2. Coupled climate–carbon-cycle models generally agree that carbon storage on land will increase as a result of the simultaneous enhancement of plant photosynthesis and water use efficiency under higher atmospheric CO2concentrations, but will decrease owing to higher soil and plant respiration rates associated with warming temperatures3. At present, the balance between these effects varies markedly among coupled climate–carbon-cycle models, leading to a range of 330 gigatonnes in the projected change in the amount of carbon stored on tropical land by 2100. Explanations for this large uncertainty include differences in the predicted change in rainfall in Amazonia45 and variations in the responses of alternative vegetation models to warming6. Here we identify an emergent linear relationship, across an ensemble of models7, between the sensitivity of tropical land carbon storage to warming and the sensitivity of the annual growth rate of atmospheric CO2 to tropical temperature anomalies8. Combined with contemporary observations of atmospheric CO2 concentration and tropical temperature, this relationship provides a tight constraint on the sensitivity of tropical land carbon to climate change. We estimate that over tropical land from latitude 30° north to 30° south, warming alone will release 53±17 gigatonnes of carbon per kelvin. Compared with the unconstrained ensemble of climate–carbon-cycle projections, this indicates a much lower risk of Amazon forest dieback under CO2-induced climate change if CO2 fertilization effects are as large as suggested by current models9. Our study, however, also implies greater certainty that carbon will be lost from tropical land if warming arises from reductions in aerosols10 or increases in other greenhouse gases11.

4 comments:

  1. This paper seems to say that in the tropics warming releases CO2 from the land. So warming is the cause of CO2 increase, not the result of CO2 increase?

    It would be interesting to know how this paper relates to what Murray Salby recently presented to the Sydney Institute that warming releases CO2 from the oceans.

    Now this paper is saying that warming releases CO2 from the land.

    ReplyDelete
    Replies
    1. Warming releases CO2 from land and ocean

      Warming is the cause of increased CO2, not the reverse

      http://hockeyschtick.blogspot.com/2013/01/single-graph-demonstrates-man-made-co2.html

      Delete
  2. http://www.newsmax.com/Newsfront/rainforests-global-warming/2013/03/10/id/493990

    ReplyDelete
  3. http://www.nature.com/news/tropical-forests-unexpectedly-resilient-to-climate-change-1.12570

    ReplyDelete

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