The Fate of Tropical Rainforests in a Super CO2-Enriched and Warmer World
Jaramillo, C., Ochoa, D., Conteras, L., Pagani, M., Carvajal-Ortiz, H., Pratt, L.M., Krishnan, S., Cardona, A., Romero, M., Quiroz, L., Rodriguez, G., Rueda, M.J., de la Parra, F., Moron, S., Green, W., Bayona, G., Montes, C., Quintero, O., Ramirez, R., Mora, G., Schouten, S., Bermudez, H., Navarrete, R., Parra, F., Alvaran, M., Osorno, J., Crowley, J.L., Valencia, V. and Vervoort, J. 2010. Effects of rapid global warming at the Paleocene-Eocene boundary on neotropical vegetation. Science 330: 957-961.
But was that really so? Did the ancient warming of the world truly constitute a major problem for the planet's rainforests?
In an attempt to answer this important question, the 29 researchers, hailing from eight different countries, analyzed pollen and spore contents and the stable carbon isotopic composition of organic materials obtained from three tropical terrestrial PETM sites in eastern Colombia and western Venezuela; and this work revealed -- contrary to the prevailing wisdom of the recent past -- that the onset of the PETM was "concomitant with an increase in diversity produced by the addition of many taxa (with some representing new families) to the stock of preexisting Paleocene taxa." And they determined that this increase in biodiversity "was permanent and not transient."
In discussing their findings, Jaramillo et al. write that "today, most tropical rainforests are found at mean annual temperatures below 27.5°C," and they say that several scientists have argued that "higher temperatures could be deleterious to the health of tropical ecosystems," citing Stoskopf (1981), Bassow et al. (1994), Lewis et al. (2004), Huber (2008, 2009) and Tewksbury et al. (2008) in this regard. In fact, they report that tropical warming during the PETM is actually believed to have produced intolerable conditions for tropical ecosystems, citing the writings of Huber (2008, 2009). Nevertheless, they reiterate that at the sites that they studied, "tropical forests were maintained during the warmth of the PETM (~31° to 34°C)," and they thus conclude that "it is possible that higher Paleocene CO2 levels (Royer, 2010) contributed to their success."
In regard to this hypothesis, it should be noted that such would indeed appear to be the case, in light of what is now the well-established fact that most plants, including trees, tend to exhibit their greatest photosynthetic rates at ever warmer temperatures as the air's CO2 content continues to rise (see Interactive Effects of CO2 and Temperature on Plant Growth in our Topical Archive).
In light of Jaramillo et al.'s impressive findings, therefore, it is becoming ever more clear that greater warmth and atmospheric CO2 concentrations are not the "twin evils" that the world's climate alarmists typically make them out to be. Quite to the contrary, they are just what the good earth's ecosystems need, in order to make them both more stable and more productive, which characteristics are absolutely essential for sustaining the still-expanding human population of the planet, as well as preserving what yet remains of what we could call wild nature.
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