Meridional overturning circulation conveys fast acidification to the deep Atlantic Ocean posing a severe threat to cold-water coral habitats.

Increasing atmospheric carbon dioxide concentrations are increasing the acidity of the oceans and reducing carbonate-ion concentrations, making it difficult for corals to maintain their calcium carbonate skeletons. This paper reports a roughly 40 per cent reduction in the transport of carbonate ions to the deep North Atlantic ocean since preindustrial times, with implications for cold-water... Continue Reading →

Ocean acidification affects coral growth by reducing skeletal density

Ocean acidification (OA) threatens coral reef futures by reducing the concentration of carbonate ions that corals need to construct their skeletons. However, quantitative predictions of reef futures under OA are confounded by mixed responses of corals to OA in experiments and field observations. We modeled the skeletal growth of a dominant reef-building coral, Porites, as a... Continue Reading →

Significant changes in the nutrient, carbon, and trace metal balances of the Arctic Ocean are underway

Rising temperatures in the Arctic Ocean region are responsible for changes such as reduced ice cover, permafrost thawing, and increased river discharge, which, together, alter nutrient and carbon cycles over the vast Arctic continental shelf. We show that the concentration of radium-228, sourced to seawater through sediment-water exchange processes, has increased substantially in surface waters... Continue Reading →

Explaining extreme events from a climate perspective

This special report of the Bulletin of the American Meteorological Society (BAMS) presents some extreme events in 2016, such as the record global heat, the heat across Asia, the 2015-16 El Niño and a marine heat wave off the coast of Alaska, and discusses how human-caused climate change may have affected the strength and likelihood of these extreme events.... Continue Reading →

Deep oceans may acidify faster than anticipated due to global warming

Oceans worldwide are undergoing acidification due to the penetration of anthropogenic CO2 from the atmosphere. The rate of acidification generally diminishes with increasing depth. Yet, slowing down of the thermohaline circulation due to global warming could reduce the pH in the deep oceans, as more organic material would decompose with a longer residence time. To... Continue Reading →

Highlights of the findings of the U.S. global change research program climate science special report

This executive summary presents the Fourth National Climate Assessment (NCA4), an authoritative assessment of the science of climate change, with a focus on the United States. This represents the first of two volumes of the Fourth National Climate Assessment, mandated by the Global Change Research Act of 1990. https://science2017.globalchange.gov/chapter/executive-summary/

Shift from coral to macroalgae dominance on a volcanically acidified reef

Rising anthropogenic CO2 in the atmosphere is accompanied by an increase in oceanic CO2 and a concomitant decline in seawater pH. This phenomenon, known as ocean acidification (OA), has been experimentally shown to impact the biology and ecology of numerous animals and plants, most notably those that precipitate calcium carbonate skeletons, such as reef-building corals.... Continue Reading →

The reinvigoration of the Southern Ocean carbon sink

Several studies have suggested that the carbon sink in the Southern Ocean—the ocean’s strongest region for the uptake of anthropogenic CO2 —has weakened in recent decades. We demonstrated, on the basis of multidecadal analyses of surface ocean CO2 observations, that this weakening trend stopped around 2002, and by 2012, the Southern Ocean had regained its... Continue Reading →

The influence of environmental variability on the biogeography of coccolithophores and diatoms in the Great Calcite Belt

The Great Calcite Belt (GCB), a region of high calcite concentration from coccolithophores, covers 60 % of the Southern Ocean area. We examined the influence of temperature, macronutrients, and carbonate chemistry on the distribution of mineralizing phytoplankton in the GCB. Coccolithophores occupy a niche in the Southern Ocean after the diatom spring bloom depletes silicic acid.... Continue Reading →

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