Coral Reef Cores

Coral reefs grow in warm, saline water in the tropics and subtropics. They accumulate layer upon layer on an annual basis and leave a record of their growth (and the climate) much like rings on trees or rings on fish scales. Scientists can drill into a reef, remove the core and obtain information about past climates, such as:

• The presence of upwelling currents can be determined from analysis of isotopes in the coral. Upwelling currents are associated with sea surface temperatures, so data about the sea surface temperature can be obtained in this manner.
• Ocean currents also influence upwelling currents so information about direction and strength of sea surface currents can also be obtained from the knowledge of upwelling currents. Sea surface currents are dependent on winds and surface temperatures.
• Surface salinity and temperature affect the density of coral layers. By measuring the density, more information about temperature and salinity can be determined.
• By analysis of the species that make up the coral reef, one can determine sea level changes. Some species grow only near the surface; others grow better in deeper waters.

Coral reef cores give data with a scope of a few thousand years ago, a little more than written records. However, this data only gives annual changes; not daily or seasonal.

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