Rate of Iceland Sea acidification from time series measurements
1Marine Research Institute, Skulagata 4, IS 121 Reykjavík, Iceland
2University of Iceland, Askja, 101 Reykjavík, Iceland
3National Energy Authority of Iceland, Grensasvegur 9, 108 Reykjavík, Iceland
4Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA
Abstract. The Iceland Sea is one part of the Nordic Seas. Cold Arctic Water prevails there and the deep water is an important source of North Atlantic Deep Water. We have evaluated time series observations of measured pCO2 and total CO2 concentration from discrete seawater samples during 1985–2008 for changes in response to increasing atmospheric carbon dioxide. The surface pH in winter decreases 0.0024 yr−1, which is 50% faster than those at two subtropical time series stations, BATS and ESTOC. In the deep water regime (>1500 m), the rate of pH decline is ¼ of that observed in surface waters. The surface calcium carbonate saturation states (Ω) are about 1.5 for aragonite and 2.5 for calcite, and are about ½ those for subtropical waters. During the period 1985–2008, the degree of saturation (Ω) decreased at a rate of 0.0072 yr−1 for aragonite and 0.012 yr−1 for calcite. The aragonite saturation horizon is currently at 1750 m and rising at 4 m yr−1. Based on local hypsography, each year causes 800 km2 of sea floor, previously bathed in saturated waters, to be exposed to undersaturation conditions.