The temperature of the earth and its oceans has been increasing since the mid 20th century, because of increasing concentrations of greenhouse gases in the atmosphere, mainly from human activities such as fossil fuel burning and deforestation. According to the 2007 Intergovernmental Panel on Climate Change (IPCC), sea surface temperatures rose by almost 1°C from 1906-2005, and the rate of increase is getting quicker. This warming not only affects the surface waters, but these increases have penetrated to depths of at least 700 m, well within the depth zone of cold-water corals.
As cold water corals are restricted to fairly narrow temperature ranges, any changes may have a dramatic effect on their health and survival. Recently, laboratory experiments on Lophelia pertusa colonies showed that an increase in temperature of just 5°C from the temperature they are used to, caused a three-fold increase in their energy demands. This increased energy demand would have to be matched by an increased food supply to the corals to enable them to grow and survive. No one knows whether food supply to these corals will keep pace, or whether food production in the oceans will be changed by these temperature changes – if food becomes limiting the corals may simply starve.