155 scientists from 26 countries have issued a declaration on the severe threat posed by ocean acidification following the 2nd symposium on “The Ocean in a High-CO2 World” held on 6-9 October 2008 at the Oceanography Museum of Monaco.

The Monaco Declaration, issued on 30 January 2009, states:

Ocean acidification is accelerating and severe damages are imminent
Currently the average concentration of atmospheric CO2 is 385 parts per million (ppm) [and increasing] At that 560-ppm level, it is expected that coral calcification rates would decline by about one-third. Yet even before that happens, formation of many coral reefs is expected to slow to the point that reef erosion will dominate. Reefs would no longer be sustainable. By the time that atmospheric CO2 reaches 450 ppm, it is projected that large areas of the polar oceans will have become corrosive to shells of key marine calcifiers.

Unfortunately, despite these specific findings, the policy recommendations made by the Declaration are vague and do not state a quantitative level to stabilise atmospheric carbon dioxide that will avoid significant impacts to the marine ecosystem.

The Declaration merely urged policymakers to develop “ambitious, urgent plans to cut emissions drastically” as one of four types of qualitative initiatives.

The Declaration is one of several made by marine scientists in recent years on the threat of climate change and ocean acidification, such as the Consensus Declaration on Coral Reef Futures issued by 50 Australian scientists from the ARC Centre of Excellence for Coral Reef Studies in 2007.
Some previous statements by similar international symposia have been more specific and suggested quantitative stabilisation targets. The Third International Tropical Marine Ecosystem Management Symposium in Mexico in October 2006 and the International Coral Reef Initiative General Meeting held in Japan in April 2007 stated that the actions required to support reef resilience to climate change include:

Limit climate change to ensure that further increases in sea temperature are limited to 2°C above preindustrial levels and ocean carbonate ion concentrations do not fall below 200 mol. kg-1.

The Monaco Declaration adds to the calls for urgent action to address the threats of climate change and ocean acidification but the vagueness of its recommendations means it is unlikely to alter national policies in this area.