Abstract
Abstract. This study aims to evaluate the potential for impacts of ocean acidification on North Atlantic deep-sea ecosystems in response to IPCC AR5 Representative Concentration Pathways (RCPs). Deep-sea biota is likely highly vulnerable to changes in seawater chemistry and sensitive to moderate excursions in pH. Here we show, from seven fully coupled Earth system models, that for three out of four RCPs over 17% of the seafloor area below 500 m depth in the North Atlantic sector will experience pH reductions exceeding −0.2 units by 2100. Increased stratification in response to climate change partially alleviates the impact of ocean acidification on deep benthic environments. We report on major pH reductions over the deep North Atlantic seafloor (depth >500 m) and at important deep-sea features, such as seamounts and canyons. By 2100, and under the high CO2 scenario RCP8.5, pH reductions exceeding −0.2 (−0.3) units are projected in close to 23% (~15%) of North Atlantic deep-sea canyons and ~8% (3%) of seamounts – including seamounts proposed as sites of marine protected areas. The spatial pattern of impacts reflects the depth of the pH perturbation and does not scale linearly with atmospheric CO2 concentration. Impacts may cause negative changes of the same magnitude or exceeding the current target of 10% of preservation of marine biomes set by the convention on biological diversity, implying that ocean acidification may offset benefits from conservation/management strategies relying on the regulation of resource exploitation.
Highlights
Global ocean anthropogenic carbon inventories suggest that the ocean took up a cumulative ∼ 155 ± 31 Pg C (1015 g of carbon) in 2010 (Khatiwala et al, 2013)
This study aims to evaluate the potential for impacts of ocean acidification on North Atlantic deep-sea ecosystems in response to IPCC AR5 Representative Concentration Pathways (RCPs)
By 2100, and under the high CO2 scenario RCP8.5, pH reductions exceeding −0.2 (−0.3) units are projected in close to 23 % (∼ 15 %) of North Atlantic deep-sea canyons and ∼ 8 % (3 %) of seamounts – including seamounts proposed as sites of marine protected areas
Summary
Global ocean anthropogenic carbon inventories suggest that the ocean took up a cumulative ∼ 155 ± 31 Pg C (1015 g of carbon) in 2010 (Khatiwala et al, 2013). This uptake of CO2 is causing profound changes in seawater chemistry resulting from increased hydrogen ion concentration (decrease in pH, pH = −log10[H+]), referred to as ocean acidification (IPCC, 2011). While waste disposal, fishing and, in the future, mineral extraction are well recognized as dominant human pressures (Ramirez-Llodra et al, 2011), expert assessments urge consideration of climate change and ocean acidification impacts in future ecosystem conservation/management strategies (Taranto et al, 2012; Billé et al, 2013)
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