A new paper published in the journal Marine Ecology Progress Series shows that the more stressors a coral reef experiences, the lower its survival rates. The study compared growth rates and other indicators on samples of Porites porites that had been pre exposed to elevated CO2 levels. One sample was then also subjected to increased water temperatures and this had a 44% lower growth rate than that of the coral exposed to high C02 levels only. (Image from Shutterstock).