Acidification: Background and History

Abstract

The ocean and the atmosphere exchange massive amounts of carbon dioxide (CO2). The pre-industrial influx from the ocean to the atmosphere was 70.6 Gt C yr –1 , while the flux in the opposite direction was 70 Gt C yr –1 ( IPCC 2007 ). Since the Industrial Revolution an anthropogenic flux has been superimposed on the natural flux. The concentration of CO2 in the atmosphere, which remained in the range of 172–300 parts per million by volume (ppmv) over the past 800 000 years ( Lüthi et al. 2008 ), has increased during the industrial era to reach 387 ppmv in 2009. The rate of increase was about 1.0% yr –1 in the 1990s and reached 3.4% yr –1 between 2000 and 2008 ( Le Quéré et al. 2009 ). Future levels of atmospheric CO2 mostly depend on socio-economic parameters, and may reach 1071 ppmv in the year 2100 ( Plattner et al. 2001 ), corresponding to a fourfold increase since 1750. As pointed out over 50 years ago, ‘human beings are now carrying out a large scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future’ ( Revelle and Suess 1957 ). Anthropogenic CO2 has three fates. In the years 2000 to 2008, about 29% was absorbed by the terrestrial biosphere and 26% by the ocean, while the remaining 45% remained in the atmosphere ( Le Quéré et al. 2009 ). The accumulation of CO2 in the atmosphere increases the natural greenhouse effect and generates climate changes ( IPCC 2007 ). It is estimated that the surface waters of the oceans have taken up 118 Pg C, or about 25% of the carbon generated by human activities since 1800 ( Sabine et al. 2004 ). By taking CO2 away from the atmosphere, the oceanic and terrestrial sinks mitigate climatic changes. Should their efficiency decrease, more CO2 would remain in the atmosphere, generating larger climate perturbations. This book has four main groups of chapters.

Elevated pCO2 enhances bacterioplankton removal of organic carbon

“…Bubbling was conducted at experimental temperatures, which were identical to the in situ temperatures of the inoculums. In the Sargasso Sea experiment, p CO 2 was adjusted through the addition of 0.206 g CaCO 3 , 0.032 g NaHCO 3 , and 29 mL of 0.1 N HCL according to the best practices guide [ 23 ]. This closed system approach results in an inorganic carbon perturbation that is chemically identical to bubbling [ 24 ].…”

Geographic variation in acid–base balance of the intertidal crustaceanCyclograpsus cinereus(Decapoda, Grapsidae) during air exposure

“…High quantities of CO 2 in oceans (i.e. hypercapnia) are producing a calcium carbonate saturation horizon to shoals in many regions, particularly in high latitudes (Gatusso & Hanson, 2011). Hypercapnia can impact marine organisms both via decreased calcium carbonate (CaCO 3 ) saturation, which affects calcification rates, and via disturbance to acid–base physiology.…”

Towards improved socio-economic assessments of ocean acidification’s impacts

“…It is not the goal of the present paper to review biological effects; however, some general trends are presented. For a comprehensive review see Gattuso and Hansson ( 2011a ).…”

“…Because of the initial hypothesis that OA will primarily alter calcification through changing seawater carbonate concentration and saturation state of calcium carbonate, the first experimental work focused on calcifying organisms (Fabry 2008 ). It appears now that many other biological functions are sensitive to OA extending to almost all forms of life, from fish to bacteria (Gattuso and Hansson 2011a ). The impact of OA can be severe and can potentially lead to species extinction (e.g.…”

“…These effects also depend on species-specific capacities to compensate. Additional physiological disturbances have been reported, including behavioural changes, reductions in fertilization and reproductive success through development effects to eggs, larvae and juveniles (Gattuso and Hansson 2011a ). Impacts from OA can be modulated and exacerbated when combined with other environmental parameters such as food availability, temperature increases or hypoxia (Pörtner and Farrell 2008 ; Thomsen et al 2010 ; Gruber 2011 ).…”