Dec 30 2008
The places and the changes described vary in the immediacy and severity of the issues faced, ranging from the current crisis in Darfur (the conflict intensified by the decades long drought) to changes in the taste of wines grown in northern Europe (grapes are ripening too fast). While many of the scenarios are pretty scary, there is one that scares me the most. The potential destruction of the coral reefs.
What are coral reefs?
Corals reefs are marine structures created by Corals, a marine animal that secretes calcium carbonate exoskeletons. Over time, the exoskeletons build on each other, creating enormous structures that support the coral and become home to a wide diversity of plant and animal life. Estimates are that 25% of all marine life call the coral reefs home.
Why are coral reefs threatened?
Several reasons. Approximately 1/3 of the carbon produced since the industrial revolution has gone into the ocean. The increase in carbon has changed the pH of the ocean from 8.2 to 8.1. The less alkaline (more acidic) water wears away at calcium carbonate exoskeletons, including those in crabs, mullosks, and coral.
In addition, the warmer water adds stress to the coral colonies. In 1998 and 2002, this additional stress caused the Great Barrier Reef to “bleach” or expel the symbiotic algae that gives them color and protects them. As a result of these bleaching episodes it is estimated that 10% of the Great Barrier Reef was lost.
While some bleaching has always occurred, before 1980, it had been limited to local areas. Since the 80s, as global temperatures have increased, the bleaching effect has grown global, affecting thousands of square kilometers. In 1998 every major reef system in the world was affected by bleaching. In 2002, more than 60% of the great barrier reef bleached.
What is the impact?
Coral Reefs are fragile ecosystems. Changes in the temperature or pH of the ocean water can profoundly damage the reefs. When the coral is damaged, other types of algae move in, overwhelming the local ecosystem.
Coral Reefs are an important part of the ocean food chain. We are seeing the effect of coral damage in Australia, where the population of sea birds is already down. As coral damage worsens, the oceanic food chain will be threatened.
In many areas the coral reefs provide protection for the coastline, preventing erosion, and protecting beaches and dwellings. Without the coral reefs, these areas would be endangered.
What can or is being done?
In the long term, the only thing that will work is reducing the greenhouse gases in our atmosphere, so that the temperature rise in the oceans is held to a minimum. At this point, however, it is unclear if enough can be done to stop the damage. There are several groups studying the problem, and some good resources if you would like to learn more.
The Coral Reef Targeted Research & Capacity Building for Management (CRTR) Program is perhaps the most comprehensive source of information and news.
Global Coral Reef Alliance is a smaller organization that also provides a wealth of information as well as great images