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Paleo Slide Set: Coral Paleoclimatology:Natural Record of Climate change for High School Student
Coral bleaching at Uva Island, Panama during thermocline shoaling in 1993.
This coral reef off the coast of Uva Island, Panamá in the eastern Pacific, has been above the surface for too long in the mid-day sun. The coral reef has bleached and died along with the algae, fish and invertebrates trapped on the reef flat. This was caused by a low spring tide that happened at the same time as an unusually extreme climate event, highlighted by strong pressure variations and winds which drive surface waters westward off the eastern Pacific coastline. A spring tide occurs when the moon, sun and earth are positioned in a straight line (at either a full or new moon). The increased gravitational pull causes lower than normal low tides and higher than normal high tides. (More about this unusual climate event in slide 20.)

In addition to being an important habitat for 100's of creatures, coral reefs are also important to scientists who study past climates.

What is climate and how is it different from weather? Weather is what we experience from hour to hour and day to day. Climate is the average of weather (temperature, humidity, pressure, wind, etc.) over decades, centuries or millennia. The climate of a region does not vary greatly from year to year, although over long periods of time it does.

Why would we want to know what the climate was like hundreds or thousands of years ago? Isn't it only necessary to know what the climate will be like in the future? Studying past climate actually assists scientists in forecasting future climate conditions. By knowing how climate has changed over the course of geologic time, scientists will be able to identify patterns and thereby predict what climate changes we are likely to see in the future. They can also compare the rate at which the climate changed in the past to the rate of climate change in today’s industrial age. It is necessary to establish what is "normal" in order to determine what changes are causes for alarm. Scientists who study past climates are called paleoclimatologists. "Paleo" means ancient (as in paleontologist, one who studies ancient life, including dinosaurs) and "climatologist" is a person who studies the average of daily weather events over time.

Humans have kept an accurate record of the weather and climate conditions over the past 100-150 years using scientific instruments. (We know climate varied much more before the "instrumental period" of observation.) To understand climate change that occurred before the instrumental period, scientists study older human records: sailing logs of early traders, letters sent home from world explorers, clothing drawn on pottery remains and the dairies of early settlers. Scientists can also utilize the natural climate record by investigating tree rings, layers of ice in glaciers, corals, ocean and lake sediments and other sources to arrive at a more accurate portrayal of the Earth's past climate.

Photo Credits:
Mark Eakin
NOAA Paleoclimatology Program

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Last Modified: 12 October 2001

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