Antarctic Ice Sheet retreat in the Amundsen Sea driven by central tropical Pacific SST variability

A new study appeared in Nature Geoscience (Jenkins et al., 2018) analyzed ocean temperature, salinity, dissolved-oxygen and current measurements from 2000 to 2016 near the Dotson Ice Shelf in the Amundsen Sea to determine temporal changes in net basal melting. The study showed that a decadal cycle dominates the ocean record, which is highly correlates with... Continue Reading →

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 →

Arctic sea-ice decrease may suppress U.S. tornado activity in summer

The observed losses in  Arctic sea ice during the past decades have been linked to the relaxation of poleward thickness gradients (thus weakened zonal winds) and a slower eastward progression of Rossby waves in the upper-level, which help promote prolonged extreme weather conditions, such as heat waves, within the mid-latitudes (e.g., Francis & Vavrus, 2012). However, the background... 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 →

Observed rapid bedrock uplift in Amundsen Sea Embayment promotes ice-sheet stability

An article published in Science analyzed GPS station data collected around the West Antarctica to report a rapid uplift of the Amundsen Sea Embayment in response to ice mass loss during the recent decades. This suggests that as ice mass is lost, the crust rebounds much faster than previously expected (thought to occur on a time scale of 10,000 years)... 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 →

Antarctic ice sheet lost 2,720 ± 1,390 billion tonnes of ice between 1992 and 2017

A team of scientists leading the ice sheet mass balance inter-comparison exercise (IMBIE) combined satellite observations of the Antarctic ice sheet, its changing volume, flow and gravitational attraction with modelling of its surface mass balance from 1992 to 2017.  Their report, recently published in Nature, showed that the Antarctic ice sheet lost 2,720 ± 1,390 billion tonnes of... Continue Reading →

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