Oceanography

A paper in Scientific Reports posits a new cause of the ice age that covered large parts of the Northern Hemisphere 2.6 million years ago.

The study found a previously unknown mechanism by which the joining of North and South America changed the salinity of the Pacific Ocean and caused major ice sheet growth across the Northern Hemisphere. The change in salinity encouraged sea ice to form which in turn created a change in wind patterns, leading to intensified monsoons. These provided moisture that caused an increase in snowfall and the growth of major ice sheets, some of which reached over a mile in thickness.


If your glass is half full, you recognize that in recent geological history, 90,000 of every 100,000 years have been ice ages, and it's been 12,000 years since the last one. In that light, global warming might be a good thing.


If the Greenland ice sheet ever gets past its stability threshold, it won't be the first time. 

400,000 years ago, a nearly complete deglaciation of southern Greenland happened, raising global sea levels as much as 6 meters. Not quite what was predicted to have happened by 2016 in "An Inconvenient Truth", but a substantial rise nonetheless.

The study authors say this is one of the first to zero in on how the vast Greenland ice sheet responded to warmer temperatures during that period, which were caused by changes in the Earth's orbit around the sun.


The Greenland Ice Sheet is huge, a 1.7 million-square-kilometer, 2-mile thick layer of ice that covers Greenland.

In the last 40 years, ice loss from the Greenland Ice Sheet has increased four-fold, contributing to global sea level rise. Some of the melting at the surface of the ice sheet is due to a warmer atmosphere but the ocean's role in driving ice loss largely has been a mystery.

A new paper in Nature Geoscience sheds new light on the connection between the ocean and Greenland's outlet glaciers, and provides important data for future estimates of how fast the ice sheet might melt and how much mass could be lost. 


Researchers have found that Mediterranean Sea warming and acidification is happening  at unprecedented rates – the main reason, they believe, is emissions of carbon dioxide into the atmosphere, which causes warming of the atmosphere and the ocean as well as acidification of its waters due to uptake of CO2 by surface waters.

300 million inhabitants and tourists of Mediterranean coastal societies rely on this ecosystem.


After analyzing core samples from the seabed off the coast of Spain and Portugal, near the Strait of Gibraltar, scientists say they have proof of shifts of climate change over the past six million years.  

The team also discovered new evidence of a deep-earth tectonic pulse in the region, as well as thick layers of sand within mountains of mud in a vast sheet, spreading out nearly 100km into the Atlantic from the Gibraltar gateway.

The quantity of sand is far more than was expected and has been caused by the strength, speed and long duration of bottom currents flowing through the Strait of Gibraltar from the Mediterranean.


Researchers from the U.S. Geological Survey and McGill University have found here is new permafrost forming around Twelvemile Lake in the interior of Alaska. 

Twelvemile Lake, and many others like it, have been shrinking over the past thirty years, now being 15 feet shallower than three decades ago. 

As the lake recedes, bands of willow shrubs have grown up on the newly exposed lake shores over the past twenty years. What Martin Briggs from the U.S. Geological Survey and Prof. Jeffrey McKenzie from McGill's Dept. of Earth and Planetary Science have just discovered is that the extra shade provided by these willow shrubs has both cooled and dried the surrounding soil, allowing new permafrost to expand beneath them.


Deep sea fish help keep more than one million tons of CO2 from UK and Irish surface waters every year - that's worth £10 million per year in carbon credits, if anyone actually paid full price for those. Those fish living in deep waters on the continental slope around the UK may play an important role in carrying carbon from the surface to the seafloor, but they do it solely for free. 


Evidence for massive and abrupt iceberg calving in Antarctica dating back 19,000 to 9,000 years ago is based on an analysis of new, long deep sea sediment cores extracted from the region between the Falkland Islands and the Antarctic Peninsula. 

The study in Nature documents that the Antarctic ice sheet is unstable and can abruptly reorganize Southern Hemisphere climate and cause rapid global sea level rise. 


Two new shipping routes have opened in the Arctic: the Northwest Passage through Canada, and the Northern Sea Route, a 3,000-mile stretch along the coasts of Russia and Norway connecting the Barents and Bering seas.

Overall, it means for the first time in perhaps 2 million years, the north Pacific and north Atlantic oceans are navigable, and that means new opportunities for Arctic natural resources and interoceanic trade with lower environmental impact, but commercial ships often inadvertently carry invasive species. Organisms from previous ports can cling to the undersides of their hulls or be pumped in the enormous tanks of ballast water inside their hulls.