Corals provide information on climate change according to NOAA
How can scientists learn about climate from these beautiful and essential underwater ecosystems? Many coral reefs have been around for millions of years, yet they are extremely sensitive to changes in climate conditions. Corals are affected by ocean warming (sometimes bleaching when temperatures rise or fall), by pollution and runoff, and by changes in the pH of seawater, which decreases as more carbon dioxide enters the ocean-a trend known as Ocean Acidification.
As corals grow, they form skeletons by making calcium carbonate from the ocean waters. The density of these calcium carbonate skeletons changes as the water temperature, light, and nutrient conditions change, giving coral skeletons formed in the summer a different density than those formed in the winter. These seasonal variations in density produce growth rings similar to those in trees. Scientists can study these rings and other characteristics to determine the climatic conditions during the seasons in which the coral grew. These growth bands also allow scientists to date coral samples to an exact year and season.
Analyzing the composition of trapped oxygen atoms for example, is used to estimate seasonal temperature and rainfall and to build a record of how they have changed through time.
By using corals to determine the past climate in the tropical oceans, scientists can also predict future trends in the climate system. The information corals provide about the tropical oceans can be very useful in examining theEl Niño Southern Oscillation. By sampling corals in the Pacific, scientists can determine El Niño patterns over the past few hundred years and use that information to improve predictions about future episodes and changes in this natural climate pattern.
Source: NOOA
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Read about the impact of oil spills on coral reefs and the ocean acidification in the Safety4Sea articles Scientists studying impact of Deepwater Horizon oil spill on coral reefs |
