Caldeira Lab Research:Ocean acidification and ocean carbon cycle

Coral reefs may start dissolving when atmospheric CO2 doubles

Jacob Silverman, Boaz Lazar, Long Cao, Ken Caldeira, & Jonathan Erez

An investigation of the effects of rising concentrations of CO2 in the atmosphere on calcification of stony corals, based on the calculation of calcifications rates for over 9000 corals. The end results display the possibility that when CO2 concentration in the atmosphere doubles, coral reefs will stop growing and begin dissolving.

Silverman, J., B. Lazar, L. Cao, K. Caldeira, and J. Erez, 2009. Coral reefs may start dissolving when atmospheric CO2 doubles, Geophysical Research Letters 36, L05606, doi:10.1029/2008GL036282.

Global distribution and health of corals: Coral distribution is color coded according to their calcification rates as a percentage of rates prior to the Industrial Revolution. The model predicted serious effects on coral health at carbon dioxide concentrations as low as 560ppm.


Calcification rates in stony corals are expected to decline significantly in the near future due to ocean acidification. In this study we provide a global estimate of the decline in calcification of coral reefs as a result of increase in sea surface temperature and partial pressure of CO2. This estimate, unlike previously reported estimates, is based on an empirical rate law developed from field observations for gross community calcification as a function of aragonite degree of saturation (Warag), sea surface temperature and live coral cover. Calcification rates were calculated for more than 9,000 reef locations using model values of Warag and sea surface temperature at different levels of atmospheric CO2. The maps we produced show that by the time atmospheric partial pressure of CO2 will reach 560 ppm all coral reefs will cease to grow and start to dissolve.