Category Archives: Nature

Greenland ice loss greater than predicted


The latest bad news for the earth’s northern polar region from Ohio State University:

The same hotspot in Earth’s mantle that feeds Iceland’s active volcanoes has been playing a trick on the scientists who are trying to measure how much ice is melting on nearby Greenland.

According to a new study [open access] in the journal Science Advances, the hotspot softened the mantle rock beneath Greenland in a way that ultimately distorted their calculations for ice loss in the Greenland ice sheet. This caused them to underestimate the melting by about 20 gigatons (20 billion metric tons) per year.

That means Greenland did not lose about 2,500 gigatons of ice from 2003-2013 as scientists previously thought, but nearly 2,700 gigatons instead —a 7.6 percent difference, said study co-author Michael Bevis of The Ohio State University.

“It’s a fairly modest correction,” said Bevis, the Ohio Eminent Scholar in Geodynamics, professor of earth sciences at Ohio State and leader of GNET, the Greenland GPS Network.

“It doesn’t change our estimates of the total mass loss all over Greenland by that much, but it brings a more significant change to our understanding of where within the ice sheet that loss has happened, and where it is happening now.”

The Earth’s crust in that part of the world is slowly moving northwest, he explained, and 40 million years ago, parts of Greenland passed over an especially hot column of partially molten rock that now lies beneath Iceland. The hotspot softened the rock in its wake, lowering the viscosity of the mantle rocks along a path running deep below the surface of Greenland’s east coast.

During the last ice age, Greenland’s ice sheet was much larger than now, and its enormous weight caused Greenland’s crust to slowly sink into the softened mantle rock below. When large parts of the ice sheet melted at the end of the ice age, the weight of the ice sheet decreased, and the crust began to rebound. It is still rising, as mantle rock continues to flow inwards and upwards beneath Greenland.

The existence of mantle flow beneath Greenland is not a surprise in itself, Bevis said. When the Gravity Recovery and Climate Experiment (GRACE) satellites began measuring gravity signals around the world in 2002, scientists knew they would have to separate mass flow beneath the earth’s crust from changes in the mass of the overlying ice sheet.

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DroughtWatch: Another week, still no change


The latest graphic report on California’s seemingly endless dry spell from the United States Drought Monitor:

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Yet another earthquake, same epicenter


And just like the last one, less than two hours earlier, this one has been rated as a 3.0 temblor, though it felt considerably stronger, rattling our belongings, unlike the earlier shaker.

According to the U.S. Geological Survey, the quake struck at 09:31 with an epicenter three kilometers north of Casa esnl and at a depth of 11.3 kilometers, four-tenths of a kilometer nearer clear blue Southern California sky than the last one.

Given yesterday’s 2.5 shaker at the same epicenter,  we think we’re in the midst of what they call an earthquake swarm, and we sure hope things settle down soon.

Welcomed to L.A. by yet another earthquake


And the epicenter of today’s magnitude 3.0 quake was the same as yesterday’s 2.5 shaker [revised downward from the initial report of 2.7], just 3 kilometers north of the new Casa esnl in Gardena.

The U.S. Geological Center pegs the quake as a 3.0 temblor, with the epicenter 11.7 kilometers below the surface.

We could actually feel the directionality of the quake as we were sitting in front of our computer at 07:43 this morning.

Here’s the map of the quake and the range of its impact from the USGS:

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Welcomed to Los Angeles, by an earthquake


We moved into out new apartment in Southern California on the first. And it took less than three weeks for Mother Earth to give us a welcome.

It happened at 19:50, and we were sitting on our new couch when a single sharp jolt, accompanied by a sound like a car hitting the corner of our apartment building in Gardena.

The U.S. Geological Survey earthquake site gave us the info, and we discovered the epicenter was three kilometers north of our house and registered as a 2.6 shaker.

Here’s the L.A. regional map with the quake epicenter, 11 kilometers beneath the surface, shown by the yellow star [more info on the quake here]:

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Rising oceanic CO2 levels damage brains of fish


The latest research on the consequences of the gunger for fossil fuels, via the University of Miami Rosenstiel School of Marine and Atmospheric Science:

In a first-of-its-kind study, researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science and the ARC Centre of Excellence for Coral Reef Studies at James Cook University showed that increased carbon dioxide concentrations alters brain chemistry that may lead to neurological impairment in some fish.

Understanding the impacts of increased carbon dioxide levels in the ocean, which causes the ocean to become more acidic, allows scientists to better predict how fish will be impacted by future ocean acidification conditions.

“Coral reef fish, which play a vital role in coral reef ecosystems, are already under threat from multiple human and natural stressors,” said lead author of the study Rachael Heuer, a UM Rosenstiel School alumna which conducted the study as part of her Ph.D. work. “By specifically understanding how brain and blood chemistry are linked to behavioral disruptions during CO2 exposure, we can better understand not only ‘what’ may happen during future ocean acidification scenarios, but ‘why’ it happens.”

In this study, the researchers designed and conducted a novel experiment to directly measure behavioral impairment and brain chemistry of the Spiny damselfish, (Acanthochromis polyacanthus) a fish commonly found on coral reefs in the western Pacific Ocean.

During a three-week period, the scientists collected spiny damselfish from reefs off Lizard Island located on Australia’s Great Barrier Reef. The fish were separated into two groups–those exposed to ordinary CO2 “control” conditions and those exposed to elevated CO2 levels that are predicted to occur in the near future, but have already been observed in many coastal and upwelling areas throughout the world. Following the exposure, the fish were subjected to a behavioral test, and brain and blood chemistry were measured.

The unique behavioral test, employed a two-choice flume system, where fish were given the choice between control seawater or water containing a chemical alarm cue, which they typically avoid since it represents the smell associated with an injured fish of its own species.

The researchers found that the damselfish exposed to elevated carbon dioxide levels were spending significantly more time near the chemical alarm cue than the control fish, a behavior that would be considered abnormal. The measurements of brain and blood chemistry provided further evidence that elevated CO2 caused the altered behavior of the fish.

“For the first time, physiological measurements showing altered chemistry in brain and blood have been directly linked to altered behavior in a coral reef fish,” said UM Rosenstiel School Maytag Professor of Ichthyology and lead of the RECOVER Project Martin Grosell, the senior author of the study. “Our findings support the idea that fish effectively prevent acidification of internal body fluids and tissues, but that these adjustments lead to downstream effects including impairment of neurological function.”

“If coral reef fish do not acclimate or adapt as oceans continue to acidify, many will likely experience impaired behavior that could ultimately lead to increased predation risk and to negative impacts on population structure and ecosystem function,” said Heuer, currently a postdoctoral researcher at the University of North Texas. “This research supports the growing number of studies indicating that carbon dioxide can drastically alter fish behavior, with the added benefit of providing accurate measurements to support existing hypotheses on why these impairments are occurring.”

The study, titled Altered brain ion gradients following compensation for elevated CO2 are linked to behavioural alternations in a coral reef fish,  [open access]was published in the Sept. 13 online issue of the journal Scientific Reports. The study’s co-authors include: Rachael Heuer; Martin Grosell; Megan J. Welch and Jodie L. Rummer and Philip L. Munday from the ARC Centre of Excellence for Coral Reef Studies at James Cook University.

The National Science Foundation, a University of Miami Koczy Fellowship, and the ARC Centre of Excellence provided funding support for the study. Heuer was also funded by an NSF Graduate Research Fellowship to conduct the research.

Map of the day: Coral reef danger hot zones


From the National Oceanic and Atmospheric Administration’s Coral Reef Watch website, regions of the world’s oceans where rising water temperatures pose a threat to the reefs that provide breeding grounds for many of the word’s food fish:

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More from NOAA:

The NOAA Coral Reef Watch program’s satellite data provide current reef environmental conditions to quickly identify areas at risk for coral bleaching, where corals lose the symbiotic algae that give them their distinctive colors. If a coral is severely bleached, disease and partial mortality become likely, and the entire colony may die.

Continuous monitoring of sea surface temperature at global scales provides researchers and stakeholders with tools to understand and better manage the complex interactions leading to coral bleaching. When bleaching conditions occur, these tools can be used to trigger bleaching response plans and support appropriate management decisions.