Lloyd, J. and Farquhar, G.D. 2008. Effects of rising temperatures and [CO2] on the physiology of tropical forest trees. Philosophical Transactions of the Royal Society B 363: 1811-1817.
What was done
As part of an international workshop held at Oriel College, Oxford, UK, in March of 2007, the authors prepared a review of the effects of rising temperatures and atmospheric CO2 concentrations on the productivity of tropical forest trees.
What was learned
Based on their examination of the pertinent scientific literature, and using a mixture of observations and climate model outputs together with a simple parameterization of leaf-level photosynthesis incorporating known temperature sensitivities, Lloyd and Farquhar say they could find "no evidence for tropical forests currently existing 'dangerously close' to their optimum temperature range," as is often suggested by climate alarmists. Quite to the contrary, in fact, they say they found that increases in photosynthetic rates associated with increases in ambient CO2 over forthcoming decades should "more than offset" any decline in photosynthetic productivity due to higher leaf temperatures, leaf-to-air vapor pressure deficits or autotrophic respiration rates. In addition, they argue that "the magnitude and pattern of increases in forest dynamics across Amazonia observed over the last few decades are consistent with a CO2-induced stimulation of tree growth."
What it means
Not only have past increases in the atmosphere's CO2 content and temperature been a boon to the productivity of Amazonia's tropical forests -- as well as all of the world's other tropical forests ( see Trees (Types - Tropical) in our Subject Index) -- it would appear from the materials reviewed by these two highly-regarded scientists, as well as their own original research, that the productivity of earth's tropical forests will likely rise even higher in response to predicted future increases in the air's temperature and CO2 concentration.