Comments on: Decelerating growth in tropical forest trees — thanks to accelerating carbon dioxide http://climateprogress.org/2008/01/21/decelerating-growth-in-tropical-forest-trees-thanks-to-accelerating-carbon-dioxide/ The Latest on Climate Science, Solutions, and Politics Mon, 22 Mar 2010 08:16:56 -0400 http://wordpress.org/?v=2.8.5 hourly 1 By: Dano http://climateprogress.org/2008/01/21/decelerating-growth-in-tropical-forest-trees-thanks-to-accelerating-carbon-dioxide/#comment-8213 Dano Wed, 23 Jan 2008 01:02:50 +0000 http://climateprogress.org/2008/01/21/decelerating-growth-in-tropical-forest-trees-thanks-to-accelerating-carbon-dioxide/#comment-8213 Joe, I've skimmed the paper and the causation offered by the authors isn't acceleration of CO2 <i>per se</i>, it's: <blockquote>In an attempt to identify the cause of the observed changes in growth rates, we tested for relationships between community-wide growth rates and climatic changes at BCI. <b>For all stem size classes the strongest relationships were a significant increase in growth rates with increased frequency of rainfree days. This may be due to decreased cloudcover and increased light availability (Graham et al. 2003; Nemani et al. 2003) which is supported by the positive correlation between the number of rainfree days and insolation. There were also significant decreases in growth rates with decreased total precipitation and increased daily minimum temperatures.</b> Climate data are not available from the Pasoh plot, but a nearby agricultural station (c. 5 km distant) recorded a steady increase in temperatures over the study period (Fig. 1) concurrent with the deceleration in growth rates (Table 3). Decreased growth at elevated temperatures is believed to be due to the increase in plant respiration relative to photosynthesis resulting in decreased net carbon assimilation (Amthor 2000; Clark et al. 2003; Clark 2004). </blockquote> Deforestation could be an issue here as well, causing the change in rainfall patterns and insolation (fewer clouds). Nonetheless, it is very likely that some sort of human activity is the cause. Best, D Joe, I’ve skimmed the paper and the causation offered by the authors isn’t acceleration of CO2 per se, it’s:

In an attempt to identify the cause of the observed changes in growth rates, we tested for relationships between community-wide growth rates and climatic changes at BCI. For all stem size classes the strongest relationships were a significant increase in growth rates with increased frequency of rainfree days. This may be due to decreased cloudcover and increased light availability (Graham et al. 2003; Nemani
et al. 2003) which is supported by the positive correlation between the number of rainfree days and insolation. There were also significant decreases in growth rates with decreased total precipitation and increased daily minimum temperatures. Climate data are not available from the Pasoh plot, but a nearby agricultural station (c. 5 km distant) recorded a steady increase in temperatures over the study period (Fig. 1) concurrent with the deceleration in growth rates (Table 3). Decreased growth at elevated temperatures is believed to be due to the increase in plant respiration relative to photosynthesis resulting in decreased net carbon
assimilation (Amthor 2000; Clark et al. 2003; Clark 2004).

Deforestation could be an issue here as well, causing the change in rainfall patterns and insolation (fewer clouds). Nonetheless, it is very likely that some sort of human activity is the cause.

Best,

D

]]> By: Lou Grinzo http://climateprogress.org/2008/01/21/decelerating-growth-in-tropical-forest-trees-thanks-to-accelerating-carbon-dioxide/#comment-8200 Lou Grinzo Tue, 22 Jan 2008 14:09:32 +0000 http://climateprogress.org/2008/01/21/decelerating-growth-in-tropical-forest-trees-thanks-to-accelerating-carbon-dioxide/#comment-8200 This kind of study, plus the frightening news of faster-than-expected polar melting, is why I'm so skeptical of all the claims that fossil fuel limits will prevent us from triggering massive GW effects. We simply don't know with anything approaching the level of certainty we'd like how to map X part per million of CO2 to Y warming effect to Z impact on the biosphere to W impact on human beings. And virtually all the evidence is pointing to these effects being much more serious than even our best experts thought. This kind of study, plus the frightening news of faster-than-expected polar melting, is why I’m so skeptical of all the claims that fossil fuel limits will prevent us from triggering massive GW effects. We simply don’t know with anything approaching the level of certainty we’d like how to map X part per million of CO2 to Y warming effect to Z impact on the biosphere to W impact on human beings. And virtually all the evidence is pointing to these effects being much more serious than even our best experts thought.

]]> By: David B. Benson http://climateprogress.org/2008/01/21/decelerating-growth-in-tropical-forest-trees-thanks-to-accelerating-carbon-dioxide/#comment-8192 David B. Benson Mon, 21 Jan 2008 22:31:15 +0000 http://climateprogress.org/2008/01/21/decelerating-growth-in-tropical-forest-trees-thanks-to-accelerating-carbon-dioxide/#comment-8192 Bad scene. Thanks for posting about this. Bad scene. Thanks for posting about this.

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