Oceanography

A year-round ice-free Arctic Ocean surface could explain why the Earth of the Pliocene Epoch had the levels of carbon dioxide in the atmosphere that we have today, but we remain 3 to 9 degrees cooler than the Earth was then.


A new projection estimates that by the middle of this century there could be an average 56 percent drop in the amount of water stored in peak snowpack in the McKenzie River watershed of the Oregon Cascade Range -   if there is a 3.6 degree Fahrenheit temperature increase.

Similar impacts may be found on low-elevation maritime snow packs around the world.


Scientists using tracking data from Garwood Valley in the McMurdo Dry Valleys region of Antarctica have documented an acceleration in the melt rate of permafrost - ground ice - in a section of Antarctica where the ice had been considered stable.

The melt rates are comparable with the Arctic, where accelerated melting of permafrost has become a regularly recurring phenomenon, and the change could offer a preview of melting permafrost in other parts of a warming Antarctic continent, says Joseph Levy, a research associate at The University of Texas at Austin's Institute for Geophysics.

The paper in Scientific Reports


Shrinking sea ice cover in the North Atlantic - baby harp seals impacted most.

A new paper says satellite images have allowed researchers to gauge the relative roles that genetic, environmental and demographic factors such as age and gender may be playing in harp seal stranding rates along the U.S. and Canadian east coasts in recent years.  Recent warming in the North Atlantic gets the blame, according to the paper by advocacy group the International Fund for Animal Welfare and Duke University. 


A potential barrier to deep Antarctic circumpolar flow until the late Miocene?

If warming projections exceed estimates and rise by 1 degree Celsius, a new computer model finds that sea levels will rise about seven feet - over the next several thousand years.


But that would be duplicated for every degree of additional warmth as well.

The paper in the Proceedings of the National Academy of Sciences combined analyses of four major contributors to potential sea level rise into a collective estimate, and compared it with evidence of past sea-level responses to global temperature changes.


Satellite observations of the ice sheets of Greenland and the Antarctic haven't been around long enough, and prior methods were too inaccurate, to be able to say whether the loss of ice today will persist in the future.

Predictions of the contribution of both ice shields to the sea level by the year 2100 may be off by more than 35 centimeters - but whether they will be too high or too low is unclear. Too high is obviously no problem. Too low could be a real worry.


In October of 2011, NASA's Operation IceBridge flights over the continent over Antarctica spotted a rift that soon became the focus of international scientific attention. Seeing the rift grow and eventually form a 280-square-mile ice island gave researchers an opportunity to gather data that promises to improve our understanding of how glaciers calve.


Arctic summers could be ice-free as early as 2030, said Dr. Mark C. Serreze, director of the U.S. National Snow and Ice Data Center (NSIDC - part of the Cooperative Institute for Research in Environmental Sciences based at the University of Colorado in Boulder) in the briefing for a seminar to be held on Tuesday, July 16th, at 10 a.m. EDT. 

In the session "Environmental Impacts of the Arctic's Shrinking Sea-Ice Cover" he will examine the social and economic effects of the retreat of the Arctic Ice Cap and the opening of the Arctic Ocean.  Registration is open to everyone free of charge.

Over past centuries, the crews of ships regularly measured some basic properties of the waters through which they sailed, such as temperature and salinity. 

Though their accuracy has to be questionable, these historical observations have proven to be important for climate modelers who are trying to validate their work. In recent years, the importance of the deep ocean as a sink for the extra energy trapped by anthropogenic climate change has come to the fore.