Earth System Trend

Ocean Acidification

UNIT: Nmol kg-1

The oceans are big – 70% of the Earth surface. Scientists often thought they were just too big for humans to really affect them very much. But then they discovered that carbon dioxide emissions were changing the chemistry of the oceans, making them more acidic. The rate of change may be faster than at any other time in the last 300 million years. Corals and shellfish are already affected.

Graph Caption: Ocean acidification expressed as global mean surface ocean hydrogen ion concentration from a suite of models (CMIP5) based on observations of atmospheric CO2 until 2005 and thereafter RCP8.5.
Source: James Orr, LSCE/IPSL, France; Bopp et al. 2013 and IPCC Fifth Assessment Report, Working Group 1, Chapter 6 (Ciais et al. 2013).

Caption: Near Oua Island, Tonga
Source: Google Earth
Map Credit: IGBP,