The Ocean Is Losing Its Breath

The Ocean Is Losing Its Breath

SOURCE: Scripps Institution of Oceanography DATE: January 4, 2018 SNIP: In the past 50 years, the amount of water in the open ocean with zero oxygen has gone up more than fourfold. In coastal water bodies, including estuaries and seas, low-oxygen sites have increased more than 10-fold since 1950. Scientists expect oxygen to continue dropping even outside these zones as Earth warms. To halt the decline, the world needs to rein in both climate change and nutrient pollution, an international team of scientists including Lisa Levin, a biological oceanographer at Scripps Institution of Oceanography at the University of California San Diego, asserted in a new paper published Jan. 4 in Science. In areas traditionally called “dead zones,” like those in Chesapeake Bay and the Gulf of Mexico, oxygen plummets to levels so low many animals suffocate and die. As fish avoid these zones, their habitats shrink and they become more vulnerable to predators or fishing. But the problem goes far beyond “dead zones,” the authors point out. Even smaller oxygen declines can stunt growth in animals, hinder reproduction and lead to disease or even death. It also can trigger the release of dangerous chemicals such as nitrous oxide, a greenhouse gas up to 300 times more powerful than carbon dioxide, and toxic hydrogen sulfide. While some animals can thrive in dead zones, overall biodiversity falls. Climate change is the key culprit in the open ocean. Warming surface waters make it harder for oxygen to reach the ocean interior. Furthermore, as the ocean as a whole gets warmer, it holds less oxygen. In coastal waters, excess nutrient pollution from land...
The Bottom of the Ocean Is Sinking

The Bottom of the Ocean Is Sinking

SOURCE: LiveScience DATE: January 4, 2018 SNIP: The bottom of the ocean is more of a “sunken place” than it used to be. In recent decades, melting ice sheets and glaciers driven by climate change are swelling Earth’s oceans. And along with all that water comes an unexpected consequence — the weight of the additional liquid is pressing down on the seafloor, causing it to sink. Consequently, measurements and predictions of sea-level rise may have been incorrect since 1993, underestimating the growing volume of water in the oceans due to the receding bottom, according to a new study. [Scientists] found that around the world for two decades, ocean basins deformed an average of 0.004 inches (0.1 millimeter) per year, with a total deformation of 0.08 inches (2 mm). However, there were distinct regional patterns to the seafloor’s bending and stretching, and the amount of sag in certain parts of the ocean bottom could be significantly higher — as much as 0.04 inches (1 mm) per year in the Arctic Ocean, for a total of 0.8 inches (20 mm), the study authors reported. As a result, satellite assessments of sea-level change — which don’t account for a sinking ocean bottom — could be underestimating the amount that seas are rising by 8 percent, according to the...
Ocean oxygen decline greater than predicted

Ocean oxygen decline greater than predicted

SOURCE: Climate News Network DATE: May 10, 2017 SNIP: US scientists who have been warning that warmer oceans are more likely to be poorer in dissolved oxygen have now sounded the alarm: ocean oxygen levels are indeed falling, and seemingly falling faster than the corresponding rise in water temperature. That colder water can hold more dissolved gas than warmer water is a commonplace of physics: it is one reason why polar seas are teeming with marine life and tropical oceans are blue, clear and often relatively impoverished. In 2013, an international consortium of marine scientists warned that oxygen levels in the oceans could fall by between 1% and 7% by the century’s end. And this could, other scientists predicted, lead to what they politely called “respiratory stress” “The trend of oxygen falling is about two to three times faster than what we predicted from the decrease of solubility associated with ocean warming,” says Takamitsu Ito, of the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology, who led the...
The world’s oceans are storing up staggering amounts of heat — and it’s even more than we thought

The world’s oceans are storing up staggering amounts of heat — and it’s even more than we thought

SOURCE: The Washington Post DATE: March 10, 2017 SNIP: The world is getting warmer every year, thanks to climate change — but where exactly most of that heat is going may be a surprise. As a stunning early spring blooms across the United States, just weeks after scientists declared 2016 the hottest year on record, it’s easy to forget that all the extra warmth in the air accounts for only a fraction of the heat produced by greenhouse gas emissions. In fact, more than 90 percent of it gets stored in the ocean. And now, scientists think they’ve calculated just how much the ocean has warmed in the past few decades. A new study, out Friday in the journal Science Advances, suggests that since 1960, a staggering 337 zetajoules of energy — that’s 337 followed by 21 zeros — has been added to the ocean in the form of heat. And most of it has occurred since 1980. The new value is a number that significantly exceeds previous estimates, Trenberth [Kevin Trenberth, a senior scientist at the National Center for Atmospheric Research] noted. Compared with ocean warming estimates produced by the Intergovernmental Panel on Climate Change, the new values are about 13 percent...
Potential for Collapse of Key Atlantic Current Rises

Potential for Collapse of Key Atlantic Current Rises

SOURCE: Climate Central DATE: January 5, 2017 SNIP: The large, looping Atlantic Ocean current that keeps northwestern Europe fairly warm and influences sea levels along the U.S. coast is a key component of the Earth’s climate system. But because of global warming, it may be more likely to substantially slow down — or even collapse — than previously thought, according to two new studies. If that current, called the Atlantic Meridional Overturning Circulation, were to slow down substantially, it could lead to chillier weather in northern and western Europe, starve economically important fisheries and cause waters to rise along the U.S. coast, leading to more so-called “sunny day” flooding and storm surge when hurricanes come ashore. It could also shift tropical rain belts, causing major disruptions to regional climate in Central and South...