Oceanography

The deepest areas of the Baltic Sea have always had a low oxygen content. The inflow of fresh water is actually limited by low thresholds at the entrance to the Baltic Sea. At the same time, there is a relatively fresh layer above the denser and saltier water in the deep layer of the sea. This results in an effective stratification of the water column, which prevents the mixing of water masses necessary to transfer oxygen to the water at the bottom. During the last century, the areas of oxygen depletion have increased drastically from approximately 5,000 km2 in around 1900 to the present…

Six glaciers in West Antarctica are moving faster than they did 40 years ago. The amount of ice draining collectively from those half-dozen glaciers increased by 77 percent from 1973 to 2013, causing global sea level to rise, according to new research.  Pine Island Glacier, the most active of the studied glaciers, has accelerated by 75 percent in 40 years, according to the paper. Thwaites Glacier, the widest glacier, started to accelerate in 2006, following a decade of stability. The study is the first to look at the ice coming off the six most active West Antarctic glaciers over such an…

It is said that nothing dies of old age in the ocean, that everything gets eaten and all that remains of anything is waste. But that waste is pure gold to oceanographer David Siegel, director of the Earth Research Institute at U.C. Santa Barbara. In a study of the ocean's role in the global carbon cycle, Siegel and his colleagues used those nuggets to their advantage. They incorporated the lifecycle of phytoplankton and zooplankton — small, often microscopic animals at the bottom of the food chain —into a novel mechanistic model for assessing the global ocean carbon export.  The…

Research using satellite observations and ice thickness measurements gathered by NASA's Operation IceBridge is giving new insight into one of the processes causing Greenland's ice sheet to lose mass. A team of scientists calculated the rate at which ice flows through Greenland's glaciers into the ocean, which gives a clearer picture of how glacier flow affects the Greenland Ice Sheet and shows that this dynamic process is dominated by a small number of glaciers. Operation IceBridge has been measuring the thickness of many of Greenland's glaciers, which allowed researchers to make a more…

Temperature has been driving the fluctuating size of Peru's Quelccaya Ice Cap, not snowfall, according to a new analysis.  The Quelccaya Ice Cap is the largest ice mass in the tropics and sits 18,000 feet above sea level in the Peruvian Andes. The dramatic shrinkage of the tropical glacier in recent decades has made it a poster child for global climate change. The findings support suspicions that tropical glaciers are shrinking because of a warming climate, and could help scientists to better understand the natural variability of past and modern climate and to refine models that predict…

Deep waters formed in the northern North Atlantic fill approximately half of the deep ocean globally. As you might gather, that impacts the circum-Atlantic climate and regional sea levels and soaks up much of the excess atmospheric carbon dioxide from industrialization. Changes in this circulation mode are considered by some to be a potential tipping point in future climate change that could have widespread and long-lasting impacts including on regional sea level, the intensity and pacing of Sahel droughts, and the pattern and rate of ocean acidification and CO2 sequestration. But this…

Twice in recent history, the periodic El Niño event has caused sea level drops abruptly in the tropical western Pacific. The tides remain below normal for up to a year in the South Pacific, especially around Samoa, and Samoans call the resulting wet stench of coral die-offs arising from the low sea levels "taimasa" (pronounced [kai' ma'sa]). A team of scientists at the International Pacific Research Center, University of Hawai'i at Mānoa and at the University of New South Wales, Australia is studying the climate effects of this particular variation of El Niño.   In 1982/83 and 1997…

Satellite observations of global sea-surface temperature have shown that a 30-year upward trend slowed in the last 15 years.  It can't be due to successful mitigation, since outside the United States and a few countries in Europe, CO2 emissions have not dropped back to those levels. Some satellites carry instruments that provide a global view of the surface temperature of oceans and seas. Satellite and local readings show that sea-surface temperature rose rapidly during the 1970s and '80s but then significantly slowed in the last 15 years. Climate scientists have been scrambling to…

 Mesopelagic fishes like lantern fishes (Myctophidae) and cyclothonids (Gonostomatidae) live in the twilight zone of the ocean, between 200 and 1,000 meters deep.  With a stock estimated at 1,000 million tons so far, mesopelagic fish dominate the total biomass of fish in the ocean and are the most numerous vertebrates of the biosphere. Now it turns out they have been severely underestimated. Researchers writing in Nature Communications have estimated their numbers are 10 times higher than previous estimated, based on acoustic observations conducted during the circumnavigation of…

It's cold and snowy just about everywhere except where you expect it. Ice in northern Alaska’s lakes during winter months is on the decline, as shown by twenty years of satellite radar imagery demonstrating how changes in our climate are affecting high-latitude environments - at least in the last few decades.  Changes in air temperature and winter precipitation over the last five decades have affected the timing, duration and thickness of the ice cover on lakes in the Arctic. In this region, warmer climate conditions result in thinner ice cover on shallow lakes and, consequently, a…