Chapter 7- Dropping Acid

Kolbert next traveled to One Tree Island near the southernmost tip of the Great Barrier Reef.  Captain James Cook first encountered the Great Barrier Reef which left many to question how did coral reefs arose? Charles Lyell theorized that reefs were formed by underwater volcanoes. However, Darwin in 1835 theorized during his visit to Tahiti noticed the neighboring island of Moorea, “if the island were to sink away, Moorea’s reefs would become an atoll.”(129) Reef-building corals mastered calcification many species evolved to rely on corals for food and protection and reefs could become “ecologically extinct.” Kolbert meets an atmospheric scientist, Ken Caldeira, his research focuses on the impact and the recent changes in global temperature and how how calcification rates changed over the years. Research showed that  carbon dioxide was very dangerous to coral reefs. The first set of evidence that showed the impact of CO2 on coral reefs was the Biosphere Project conducted in late 1980s. The project concluded extremely high levels of CO2 destroyed the coral composition. A popular belief among many scientists was that the relationship between corals and saturation state, used to track ocean acidification because it’s a measure of calcium and carbonate ions, was unrelated. However, Chris Langdon, a marine biologist, believed that coral reefs did care about saturation states. But how does a lower saturation state affect corals in the near future?

In order to understand the relationship between saturation state and coral reefs readers learn that corals grow fast at saturation state of five but as the rates drop corals grow slower until they quit building. Kolbert informs the reader that reefs have vanished and resumed building during what is known as a “reef gap” which scientists believed reef building was vulnerable to environmental changes. Human activity shows that corals will soon cease to exist. More specifically, “prior to the industrial revolution, all of the world's major reefs could be found in water at an aragonite saturation state between 4 and 5. Today, there's almost no place left on the planet where the saturation state is above four, and if current emissions trends continue by 2060 there will be no regions left above 3.5. By 2100,  none will remain above three. a saturation levels fall, the energy required for calcification will increase, and decline eventually, saturation levels may drop so low that corals quit calcifying altogether.” (137) If coral reefs vanish then many marine life relies on it for food and shelter will also cease to exist. Humans are the guilty party when it comes to such changes because of threats to coral reefs like ocean acidification, over fishing, agricultural runoff, and other factors. Reefs are complex builders for the earth and its ocean without it will be very tragic for the near-future.