Threats

Introduction > Fishing and Trawling > Oil and gas > Climate Change

Global warming and the occurrence of warming related events represent a significant threat to world-wide biodiversity. With increasing CO2 in the atmosphere, there may be increased global temperature, increased frequency and ferocity of storm events, increases in the amount of freshwater released into the sea and increased sea-levels.

Modelled increases in atmospheric CO2 have been conducted by the Intergovernmental Panel on Climate Change (IPCC). The projected increases in atmospheric CO2 show a series of potential scenarios based on current and predicted hydrocarbon usage.

The potential impacts on cold-water corals include: (1) restricted bathymetric or biogeographic ranges due to increases in sea-surface temperatures, (2) potentially altered calcification rates, reef growth and recovery due to increased CO2, reduced alkalinity and calcium carbonate saturation, and disrupted large scale oceanographic circulation patterns. It may also directly affect the seawater chemistry resulting in a drop in calcium carbonate saturation of surface seawater by about 30 %. How this would affect cold-water coral ecosystems is unknown, but a significant drop in calcification rate may have significant impacts on the growth and recovery of any reef structure built from calcium carbonate.

Recently an influential report by The Royal Society, the UK's national academy of science, suggested that as well as reducing coral calcification rates, CO2-related changes in seawater chemistry could cause the depth below which coral skeletons dissolve (the aragonite saturation horizon) to become shallower by several hundred meters.

If true, this has devastating implications for the current distribution of cold-water coral reefs. Could we be about to fundamentally disturb an ecosystem we have only just discovered?

For current discussions and links to new studies see the Ocean Acidification blog.