Oceanography

A new study on biological erosion of mesophotic tropical coral reefs - low energy reef environments between 30-150 meters deep - provides new insights into processes that affect the overall structure of these important ecosystems.

The purpose of the study was to better understand how bioerosion rates and distribution of bioeroding organisms, such as fish, mollusks and sponges, differ between mesophotic reefs and their shallow-water counterparts and the implications of those variations on the sustainability of the reef structure.


Changes to Antarctic winds have been implicated in southern Australia's drying climate but a new estimate says they may also have a profound impact on warming ocean temperatures under the ice shelves along the coastline of West and East Antarctic.


Whales are relatively rare and so they probably don't make much of a difference in the overall ocean. 

A team of biologists disagrees. They reviewed several decades of research on whales from around the world and found that whales make a huge difference and have a powerful and positive influence on the function of oceans, global carbon storage, and the health of commercial fisheries. "The decline in great whale numbers, estimated to be at least 66% and perhaps as high as 90%, has likely altered the structure and function of the oceans," claims University of Vermont conservationist Joe Roman and colleagues in Frontiers in Ecology and the Environment, "but recovery is possible and in many cases is already underway."


Iron is one of the essential elements of life. Found in enzymes like myoglobin and hemoglobin and cytochrome P450, iron is an essential cog in the biomachinery of every living cell. 

Iron is present in tiny concentrations in seawater. On the order of a few billionths of a gram in a liter.  Given that there is so little iron in seawater, one might conclude that its presence there is inconsequential, but its scarcity in the ocean, the earth's wellspring of life, only magnifies its importance. 


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.