Most acidic ocean waters (current)

Based on four decades' worth of data and using 2005 as a baseline, a study that mapped ocean pH levels published in the journal Marine Chemistry on 20 August 2014 found that the consistently most acidic ocean waters are found in the Bering Sea between Russia and Alaska, USA, in the North Pacific Ocean. During the winter months, when lower temperatures mean the water retains higher levels of carbon dioxide, the pH level here can reach as low as 7.7. A few spots in the Gulf of Alaska also occasionally registered similar pH levels according to the same dataset. The average pH level across the world's oceans is currently 8.1.

pH is a measure of the acidity of a liquid solution; its scale (which is logarithmic) goes from 0 to 14. pH = 7 corresponds to neutrality; for pH < 7, the water solution is acidic while for pH > 7 is basic/alkaline. Water solutions that are more acidic will have a lower pH value.

Average pH in the world's oceans has fallen from 8.2 to 8.1 since the start of the industrial era, a 30% rise in acidity, and pH is predicted to fall to an average of 7.8 to 7.9 by 2100.

Occasionally even lower pH levels have been registered, some of which have even dipped below pH 7, but these are considered anomalies from buoy measurements.

The pH ocean mapping study was a collaboration between Columbia University's Lamont-Doherty Earth Observatory, NOAA (National Oceanic and Atmospheric Administration), the University of Alaska Fairbanks and other organizations, led by the late climate scientist Taro Takahashi.