What was done
Among other things, the authors grew nubbins of the branching zooxanthellate scleractinian coral Acropora verweyi in aquariums maintained at 20, 25 and 29°C, while weighing them once a week over a period of four weeks.

What was learned
Reynaud et al. report that coral calcification rates increased in nearly perfect linear fashion with increasing water temperature, equaling 0.06, 0.22 and 0.35% per day at 20, 25 and 29°C, respectively.

What it means
The observed response equates to an approximate 480% increase in calcification rate in response to a 9°C increase in water temperature or to a 160% increase in calcification rate in response to a 3°C increase in temperature, the latter of which temperature increases is somewhere in the low to midrange of global warming that climate alarmists claim will result from a 300 ppm increase in the air's CO2 concentration.  As noted in our Editorial of 26 Jan 2005, this positive effect of rising temperature far outweighs the negative effect of rising CO2 concentrations on calcification in corals.