Ocean carbon sink is dictated by natural variability on decadal time scales

Data-based estimates show that the global oceanic carbon flux has increased rapidly since around 2000 with little decadal variability during 1992-1999 (Rödenbeck et al., 2015). An article published in Geophysical Research Letters (Li and Ilyina, 2017) used large ensemble climate model simulations to show that the observed increase is much faster than simulated by their biogeochemical process model. By... Continue Reading →

Deglacial atmospheric CO2 increase caused by enhanced abyssal circulations in the Pacific Ocean

Paleo records indicate that during the last deglaciation period (19,000–9,000 years ago) atmospheric CO2 level increased by about 80 ppm. A new study published in Nature Geoscience analysed neodymium (Nd) isotope data in North Pacific sediment cores to find an increase in 14C age of North Pacific subsurface waters sourced from Antarctica indicating an enhanced abyssal overturning... Continue Reading →

Ship-based observations significantly underestimate carbon dioxide outgassing in the high-latitude Southern Ocean

It is widely believed that the Southern Ocean accounts for a significant portion of the oceanic uptake of anthropogenic carbon dioxide (CO2). However, flux estimates in this region are based on sparse ship-based observations that are strongly biased towards summer. A new study published in Geophysical Research Letters presented new estimates of Southern Ocean air‐sea CO2 fluxes based... Continue Reading →

Southern Hemisphere westerly winds and possible links to CO2 outgassing

Some model studies suggested that the current strengthening and poleward shift of the Southern Hemisphere (SH) westerly winds brought carbon-rich Circumpolar Deep Water (CDW) to the surface and reduced ΔpCO2, weakening the anthropocentric carbon sink (e.g., Mikaloff-Fletcher, 2015). A new study, which appeared in Nature Geoscience,  presented a 12,300-year reconstruction of SH westerly winds based on three... Continue Reading →

A coastal coccolithophore species (O. neapolitana) maintains pH homeostasis and switches carbon sources in response to ocean acidification

According to a new article published in Nature Communications, a coastal coccolithophore species (Ochrosphaera neapolitana), which has a unique mechanism for producing coccoliths, can maintains constant pH at the calcification site, regardless of CO2-induced changes in pH of the surrounding seawater. The authors of this study cultured a coccolithophore species (Ochrosphaera neapolitana), the most prolific ocean calcifiers in the ocean, under three pCO2-controlled... Continue Reading →

Antarctica and the Southern Ocean in 2070, under low and high emissions scenarios

A team of experts in biology, oceanography, glaciology, geophysics, climate science and policy, analyzed the potential impacts of two different future scenarios of carbon emissions, RCP2.6 (low emission & strong action) and RCP 8.5 (high emission & weak action), on Antarctica and the Southern Ocean. The team assessed key systems including  global average air temperature; Antarctic contribution... Continue Reading →

Man-made nutrient pollution could make coral reefs more vulnerable to ocean acidification

A team of scientists from California State University and University of Hawaii carried out a series of laboratory experiments adding nitrate and phosphate to aquariums that contain the coral reef community (corals, seaweeds and dead reef rubble). Their experiments showed that in nutrient polluted seawater, the calcification by coral reefs became less effective disrupting the relationship between... Continue Reading →

Sustained climate warming drives declining marine biological productivity

In the Southern Ocean, nutrient-rich North Atlantic Deep Water upwells to the surface, and the northward surface water sinks at mid-depth (as Subantarctic Mode Water and Antarctic Intermediate Water) and transports nutrients into the low-latitude thermocline. According to a recent article appeared in Science, climate model simulations under RCP 8.5 scenario project that the Antarctic... Continue Reading →

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 →

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