Oceanography

Methane is a greenhouse gas with more warming impact than carbon dioxide but also fortunately a much shorter life in the atmosphere.

Due to the popularity of much cleaner natural gas, which has caused CO2 emissions to drop, there are concerns about methane but the big source is nature herself - decomposition of organic material, a complex process involving bacteria and microbes, is a big culprit.

A new study demonstrates for the first time how elemental carbon became an important construction material of some forms of ocean life after one of the greatest mass extinctions in the history of Earth more than 252 million years ago. 

As the Permian Period of the Paleozoic Era ended and the Triassic Period of the Mesozoic Era began, more than 90 percent of terrestrial and marine species became extinct.

Various proposals have been suggested for this extinction event, including extensive volcanic activity, global heating, or even one or more extraterrestrial impacts.


Crocus and daffodil blossoms mean spring has arrived on land and a similar "greening" event, a massive phytoplankton bloom, unfolds each spring in the Atlantic Ocean.

But, what happens to all that organic material produced in the surface ocean? 


The ocean is a huge reservoir of dissolved organic molecules, many of them stable against microbial utilization for hundreds and even thousands of years.  They contain a similar amount of carbon as compared to carbon dioxide (CO2) in the atmosphere and the origin of these persistent molecules has been something of an enigma.

Though the developed world is concerned about greenhouse gas emissions implicated in climate change and global warming, reactions in nature have been less consistent.

Polar bears have been increasingly forced on shore due to sea ice loss, where they eat berries, birds and eggs, while ice seals, the usual lipid-rich prey of bears, couldn't be happier that thinner ice has made them harder to get to.

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.