Global Warming and Coral

Image source: Australian Government

There are two reasons why scientists have long been concerned about the effects of climate change on coral reefs. Firstly, corals will only grow in a narrow range of water temperatures. Secondly, when there is more carbon dioxide in the air, more of the gas dissolves into the sea. When carbon dioxide dissolves in water, it makes the water slightly more acidic, and this change in chemistry is likely to make it more difficult for corals to build reefs.

While the growth rate of most marine organisms usually increases with warmer water temperature, it had always been thought that many corals are damaged by small increases in maximum water temperatures. On average, global sea surface temperatures (known as SSTs) have increased over the past century but, surprisingly, there have been different responses to this change from the corals on Australia’s west coast and in the east. A 2012 study , just released, has found that coral calcification rates of reefs in higher latitudes of Western Australia have significantly increased over the past century despite rapidly rising SSTs. On the other hand, a 2009 study found that coral calcification rates along the entire Great Barrier Reef (GBR) declined over the period 1990-2005.