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 →

Satellite-derived Antarctic ice loss over the past decade is 80% higher than IPCC projections

A short article appeared in Nature Climate Change compared Antarctic ice-sheet mass balance between satellite-derived observations and IPCC-AR5 model-based projections. Satellite-derived observations show that Antarctic ice-sheet has decreased since 1992 contributing around 0.27 mm-per-yr sea level rise. During the last decade (2007-2017), the contribution from Antarctica increased to around 0.55 mm-per-yr . This value is around 30... 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 →

Increasing role of the North Atlantic in anthropogenic ocean heat uptake

Anthropogenic aerosols preferentially cool the Northern Hemisphere, and the effect on surface heat flux into the North Atlantic opposes the greenhouse gas (GHG) effect. However, aerosols are projected to decline in the near future, reinforcing the greenhouse effect on the North Atlantic heat uptake. As a result, the surface uptake of anthropogenic heat by the... 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 →

Cross-equatorial winds control El Niño diversity and change

A new study published in Nature Climate Change used idealized coupled model experiments to show that increased cross-equatorial winds in the eastern Pacific during the past decades strengthened the cold tongue (south of the equator). This in turn reduced ENSO amplitude and promoted more central Pacific (CP) - type El Nino events. https://www.nature.com/articles/s41558-018-0248-0

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 →

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