Oceanography

You never forget the first time you see an iceberg. The horizon of a ship at sea is a two dimensional space and to see a three dimensional piece of ice appear in the ocean is quite something.

But, in truth, the first iceberg you see is likely to be small.

Most icebergs that make it far enough north from Antarctica to where they are danger to shipping are sometimes many years old and at the end of their lives. They are small fragments of what once left the continent.

A 10 year project to observe and analyze regular data about ocean circulation and how it impacts on Britain’s climate has provided new insight into Atlantic Meridional Overturning Circulation (AMOC), a major system of currents in the North Atlantic.

10 years is too short a time to be meaningful but it is an important milestone. Since 2004, the project team has been monitoring the AMOC at 26.5N degrees, near where it carries its maximum heat, using instruments moored at 30 locations across the Atlantic between the Canary Islands and the Bahamas - so-called fixed arrays. The arrays’ instruments measure the temperature, salinity and pressure of the ocean, from which the AMOC’s strength and structure can be calculated.
To combat possible climate change due to greenhouse gases, a mix of alternative energy sources (except nuclear for the United States) and geoengineering schemes have been proposed. One idea proposes that ocean pipes could facilitate direct physical cooling of the surface ocean by replacing warm surface ocean waters with colder, deeper waters. 

A new study from a group of Carnegie scientists determines that these types of pipes could actually increase global warming quite drastically. 
Microbial communities in different regions of the Pacific Ocean displayed strikingly similar daily rhythms in their metabolism despite inhabiting extremely different habitats, according to a new study.  

From the nutrient-rich waters off California to the nutrient-poor waters north of Hawai'i, dominant photoautotrophs - light-loving bacteria that need solar energy to help them photosynthesize food from inorganic substances - appear to initiate a cascade effect wherein the other major groups of microbes perform their metabolic activities in a coordinated and predictable way. As expected, different photoautotrophs dominated the coastal versus open ocean but many other heterotrophic bacterial groups were common to both habitats.
Ocean tides have changed significantly over the last century at many coastal locations around the world, according to a paper in Earth’s Future, and increases in high tide levels and the tidal range were found to have been similar to increases in average sea level at several locations.

Average sea levels are rising but tide levels have undergone little change on decadal time scales, nor will they change much over the next century, so long-term changes in tides are not a concern in computer models trying to predict the effects of rising sea levels.
75 marine scientists have sent a letter to President Obama scolding the administration for its policies on seismic airgun blasting in the Atlantic Ocean,
Too cold for a penguin? An Ice Age brought on by global warming so severe penguins had to move?

Indeed. During the last interglacial, what is colloquially called an ice age though it has been such non-stop for a few million years, only three populations of emperor penguins may have survived, because much of the rest of Antarctica was uninhabitable due to the amount of ice. 
Reefs are made up of many coral species that live in a mutually beneficial symbiotic relationship with microscopically small algae hosted in their tissue. These symbiont algae produce sugars that contribute to the diet of the coral in return for shelter and nutrients that are vital for algal growth. 

A symbiotic association is vulnerable to changes in environmental conditions, like seawater temperature. Heat-stress induced loss of the algal partners from the coral host can result in the often fatal process known as 'coral bleaching'. 

A new species of algae has been discovered in reef corals of the Persian (Arabian) Gulf where it helps corals to survive seawater temperatures of up to 36 degrees Celsius - temperatures that would kill corals elsewhere.
Researchers have quantified how the Greenland Ice Sheet reacted to a warm period 8,000-5,000 years ago, when temperatures were 2-4 degrees C warmer than present and so could inform us what might happen if the same occurred now. 

Dr. Nicolaj Krog Larsen, Aarhus University in Denmark and Professor Kurt Kjær, Natural History Museum of Denmark, ventured off to Greenland to investigate how fast the Greenland Ice Sheet reacted to past warming. Over six summers, they cored lakes in the ice-free land surrounding the ice sheet. The lakes act as a valuable archive as they store glacial meltwater sediments in periods where the ice is advanced. That way it is possible to study and precisely date periods in time when the ice was smaller than present.
Remote monitoring of large swathes of otherwise inaccessible ocean using satellites reveals an alarming picture: ocean acidity.

The Earth's oceans take up about a quarter of global CO2 emissions, which can turn the seawater more acidic, making it more difficult for some marine life to live.

Rising CO2 emissions, and the increasing acidity of seawater projected over the next century, has the potential to devastate some marine ecosystems, a food resource on which we rely, and so careful monitoring of changes in ocean acidity is crucial.


Total ocean alkalinity as viewed from space. Credit: Ifremer/ESA/CNES