Oceanography

The high frequency and magnitude of volcanic eruptions could have been the cause of the progressive cooling of ocean surfaces over a period of 1,800 years, according to a new study.

The study emphasizes that this trend came to an end with the beginning of the Industrial Revolution and the resulting global warming caused by human activity. It further shows that the lowest temperatures in the first 1,800 years of the Common Era were recorded between the 16th and the 18th centuries, a period known as the "Little Ice Age".


As you all know, the ecosystem is like a giant human anti-lung - it breathes in the CO2 we exhale and helps produce oxygen.

It turns out that the Southern Ocean seasonally absorbs significantly more CO2 than they release, higher than previous estimates. Most importantly, these seas remove a large part of the CO2 that human activities emit into the atmosphere, thereby slowing down the growth of this greenhouse gas in the atmosphere, which has been lessening the rate of climate change.


Researchers from CSIRO and Imperial College London have assessed how widespread the threat of plastic is for the world's seabirds, including albatrosses, shearwaters and penguins, and found the majority of seabird species have plastic in their gut.

The study, led by Dr Chris Wilcox with co-authors Dr Denise Hardesty and Dr Erik van Sebille and published today in the journal PNAS, found that nearly 60 per cent of all seabird species have plastic in their gut.

Based on analysis of published studies since the early 1960s, the researchers found that plastic is increasingly common in seabird's stomachs.

In 1960, plastic was found in the stomach of less than 5 per cent of individual seabirds, rising to 80 per cent by 2010.


The World Glacier Monitoring Service, which compiles the results of worldwide glacier observations in annual calls-for-data, has compiled such data on glacier changes for more than 120 years.

Now they have published a new analysis of global glacier changes and say observations of the first decade of the 21st century (2001-2010) compared to all available earlier data from in-situ, air-borne, and satellite-borne observations as well as to reconstructions from pictorial and written sources leads them to believe that observed glaciers currently lose between half a meter and one meter of ice thickness every year – this is two to three times more than the corresponding average of the 20th century.

There’s a new study that’s getting a fair amount of attention in the climate science community and the popular press.


Observations of Greenland's Helheim Glacier link the process through which chunks of ice at the edge of a glacier break away, which has been hard to study, to seismically detectable events known as glacial earthquakes, which have been increasing in number in recent years.

Because seismic signals from these events can be detected by instruments located all over the globe, it should be possible to use glacial earthquakes as proxies for the glacier edge breaking process, known as calving.


Scientists have developed a computer model that clarifies the complex processes driving ocean mixing in the vast eddies that swirl across hundreds of miles of open ocean.

The Lagrangian In-situ, Global, High-performance particle Tracking (LIGHT) model is a first-of-its-kind tool because of its ability to exploit the power available from today's supercomputers, the authors say.


New research shows that surface waters of the Chukchi and Beaufort seas could reach levels of acidity that threaten the ability of animals to build and maintain their shells by 2030, with the Bering Sea reaching this level of acidity by 2044. 

"Our research shows that within 15 years, the chemistry of these waters may no longer be saturated with enough calcium carbonate for a number of animals from tiny sea snails to Alaska King crabs to construct and maintain their shells at certain times of the year," said Jeremy Mathis, an oceanographer at NOAA's Pacific Marine Environmental Laboratory and lead author. "This change due to ocean acidification would not only affect shell-building animals but could ripple through the marine ecosystem."


Over geologic time, the work of rain and other processes that chemically dissolve rocks into constituent molecules that wash out to sea can diminish mountains and reshape continents.

Scientists are interested in the rates of these chemical weathering processes because they have big implications for the planet's carbon cycle, which shuttles carbon dioxide between land, sea, and air and influences global temperatures.

A new study, published online on June 8 in the journal Nature Geoscience, by a team of scientists from Stanford and Germany's GFZ Research Center for Geosciences reveals that, contrary to expectations, weathering rates over the past 2 million years do not appear to have varied significantly between glacial and interglacial periods.


Though ocean acidification and corals have been a concern, not all coral reefs are at risk. Instead, some thrive as they have absorbed atmospheric carbon dioxide (CO2) released by the burning of fossil fuels.

In ocean acidification, the CO2 reacts with water molecules, lowering ocean pH (making it more acidic), and that process also removes carbonate, an essential ingredient needed by corals and other organisms to build their skeletons and shells.

World Oceans Day today has meant new questions about ocean acidification, which threatens coral reef ecosystems worldwide - but not all reefs.