Whilst the 1986 El Niño event began to dissipate across the eastern Pacific regions in mid 1987, the elevated sea surface temperatures remained in the central and western pacific until the early months of 1988. Associated with the 1986 El Niño was the widespread bleaching of reef corals throughout the Caribbean region, which at the time (over two decades ago) was a relatively poorly understood phenomenon.

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Above is the Niño index for 1980 - 1998, showing the average of the sea surface temperature in the tropical Pacific Ocean (5°N to 5°S, and 150°W to 90°W) compared to a long-term average temperature (Source: NASA JPL)

Although Google News is notoriously patchy before the advent of online news sources (pre 2000), there is some interesting reading in the archive files from the late 1980′s, chronicling the 1987 Caribbean bleaching event. At the onset, the New York Times note that “Experts Are Puzzled by Widespread Coral ‘Bleaching’ in Caribbean”:

“Scientists gathered here from around the Caribbean last week to discuss a mysterious ‘bleaching’ of coral throughout the region, a change that some fear portends severe damage to rich reef ecosystems” (December 15th, 1987)

At the same time, the Chicago Tribune claimed that scientists were “… at sea about coral ‘bleach’ “:

“In the past, bleaching has occurred sporadically in the Caribbean in response to environmental stresses such as pollution and changes in water temperature or salinity. But worried scientists said they had never seen such widespread bleaching. The chief suspect is warmer waters. It is too soon to know how widespread coral mortality will be, scientists said” (January 1st 1988)

As the El Nino conditions passed, the Washington Post ran with the headline “Mysterious Coral Bleaching Abates”:

“The mysterious coral bleaching phenomenon that swept through most of the Caribbean last summer seems to be over, and there are signs that the corals may be recovering without dying off.

Scientists do not know what to make of the phenomenon, but some fear it could be an early result of a global warming trend. Water temperatures in the region were higher than normal last summer, and if the phenomenon recurs in coming summers, the corals could eventually be wiped out” (December 28th, 1987)

Several years after the El Nino event, the Washington Post followed up the story with the title “Warm Seas Killing Coral Reefs; Finding May Presage More Ecological Harm”

“Until the worldwide bleaching episode of 1987, the periodic phenomenon was “virtually ignored,” Ernest Williams said. He and his colleagues found that there was also widespread bleaching in 1979-80 and 1982-83. There have been isolated reports of bleaching since 1911, though only in recent years have the episodes been so widespread” (October 12th, 1990).

However, with the benefit of hindsight, perhaps the most telling excerpt of all comes from an article published in the New Scientist from 1989:

Corals are sensitive to changes in temperature as well as to the depth of water. If the water suddenly warms by 1 to 2 Degree C, coral polyps can expel their algal partners, so that the coral looks bleached. This sometimes leads to the death of coral. In the early stages of global warming, the increase in temperature may be slow enough for both coral and algae to adapt. If this is the case, bleaching may not be a serious problem for another 40 years or so. (11th November, 1989)

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