Ocean Acidification and Corals

Guest post by Steven Goddard

The BBC ran an article this week titled “Acid oceans ‘need urgent action‘” based on the premise:

The world’s marine ecosystems risk being severely damaged by ocean acidification unless there are dramatic cuts in CO2 emissions, warn scientists.

This sounds very alarming, so being diligent researchers we should of course check the facts. The ocean currently has a pH of 8.1, which is alkaline not acid. In order to become acid, it would have to drop below 7.0. According to Wikipedia “Between 1751 and 1994 surface ocean pH is estimated to have decreased from approximately 8.179 to 8.104.” At that rate, it will take another 3,500 years for the ocean to become even slightly acid. One also has to wonder how they measured the pH of the ocean to 4 decimal places in 1751, since the idea of pH wasn’t introduced until 1909.

The BBC article then asserts:

The researchers warn that ocean acidification, which they refer to as “the other CO2 problem”, could make most regions of the ocean inhospitable to coral reefs by 2050, if atmospheric CO2 levels continue to increase.

This does indeed sound alarming, until you consider that corals became common in the oceans during the Ordovician Era - nearly 500 million years ago - when atmospheric CO2 levels were about 10X greater than they are today. (One might also note in the graph below that there was an ice age during the late Ordovician and early Silurian with CO2 levels 10X higher than current levels, and the correlation between CO2 and temperature is essentially nil throughout the Phanerozoic.)

http://ff.org/centers/csspp/library/co2weekly/2005-08-18/dioxide_files/image002.gif

Perhaps corals are not so tough as they used to be? In 1954, the US detonated the world’s largest nuclear weapon at Bikini Island in the South Pacific. The bomb was equivalent to 30 billion pounds of TNT, vapourised three islands, and raised water temperatures to 55,000 degrees. Yet half a century of rising CO2 later, the corals at Bikini are thriving. Another drop in pH of 0.075 will likely have less impact on the corals than a thermonuclear blast. The corals might even survive a rise in ocean temperatures of half a degree, since they flourished at times when the earth’s temperature was 10C higher than the present.

There seems to be no shortage of theories about how rising CO2 levels will destroy the planet, yet the geological record shows that life flourished for hundreds of millions of years with much higher CO2 levels and temperatures. This is a primary reason why there are so many skeptics in the geological community. At some point the theorists will have to start paying attention to empirical data.