Energy / Climate Change

October 11, 2013


2012 Report Indicates Rising Temperatures and Progressing Ocean Acidification Worldwide

Keywords: Climate Change Government 

OA_pHtrend_137E_en.jpg Ocean_Acidification_map.jpg
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The Japan Meteorological Agency (JMA) released its 2012 Climate Change Monitoring Report on July 12, 2013, which provides observations and analyses of the climate, and oceanographic and atmospheric environments of both Japan and the world. According to the report, the global annual mean temperature in 2012 was the 8th highest since 1891, and is increasing at a rate of 0.68 degrees Celsius per century.

The concentrations of carbon dioxide (CO2) in the atmosphere and ocean have been increasing over the long term. The global average CO2 concentration in the atmosphere was 390.9 parts per million (ppm) in 2011, up 2.0 ppm from 2010. On average, CO2 concentration has been increasing at an annual rate of 2.0 ppm in the past ten years, representing a larger rate of increase than the 1.5 ppm observed in the 1990s. The mean growth rates of oceanic CO2 concentrations from 1984 to 2012 were 1.6 ppm per year.

Ocean acidification, known as the decrease in seawater pH (potential ion hydrogen), is caused by the marine uptake of atmospheric CO2 emitted by human activity. This report also included monitoring results regarding ocean acidification for the first time.

JMA has been conducting oceanographic observations in the western North Pacific for a long time. JMA estimated the pH in surface waters at northern latitudes between 3 and 34 degrees along the 137 east longitude, one of JMA's repeat hydrographic lines, in winter since 1984 using CO2 concentration and related data in surface waters. The results revealed that pH has clearly decreased at all latitudes, and the mean decrease rate of pH was 0.017 per decade, suggesting an increase in ocean acidity. Since ocean acidification is a particular issue of concern because it accelerates global warming by reducing marine capability of CO2 uptake from the atmosphere and affects marine ecosystem, JMA will continue the monitoring of marine environment in the future.