Today, it is nearly 370 and rising as much as two parts per million each year. It's almost going to double from the pre-industrial value some time in the next century. Fossil-fuel combustion and deforestation both have contributed to rising atmospheric carbon dioxide. This increase in carbon dioxide adds to the greenhouse effect, which traps heat in the atmosphere, possibly leading to global warming. Warming trends during the last 10 years, whether from increased carbon dioxide emissions or natural climatic variation, have already caused bleaching of coral reefs.
Corals normally live in symbiosis with algal plants, but warm temperatures upset the relationship.
When that happens, corals lose their color, changing from green or brown to white. The findings are based on a series of studies showing that acidity interferes with the growth of coral reefs. Biosphere 2 is an enclosed glass and metal frame structure that houses Earth's ecosystems in miniature, including a 900,000-gallon research ocean. Coral reefs are mostly made of calcium carbonate. When carbon dioxide dissolves in water it makes carbonic acid, which causes calcium carbonate to deteriorate.