Category: Earth Science News

JUST IN: New Maps Chart Mantle Plumes Melting Greenland Glaciers

Many large glaciers in Greenland are at greater risk of melting from below than previously thought, according to new maps of the seafloor around Greenland created by an international research team. Like other recent research findings, the maps highlight the critical importance of studying the seascape under Greenland’s coastal waters to better understand and predict global sea level rise.

Uummannaq fjord

Researchers from the University of California, Irvine; NASA’s Jet Propulsion Laboratory, Pasadena, California; and other research institutions combined all observations their various groups had made during shipboard surveys of the seafloors in the Uummannaq and Vaigat fjords in west Greenland between 2007 and 2014 with related data from NASA’s Operation Icebridge and the NASA/U.S. Geological Survey Landsat satellites. They used the combined data to generate comprehensive maps of the ocean floor around 14 Greenland glaciers. Their findings show that previous estimates of ocean depth in this area were as much as several thousand feet too shallow.

Why does this matter? Because glaciers that flow into the ocean melt not only from above, as they are warmed by Sun and air, but from below, as they are warmed by water.

Iceland - Greenland Mid-Atlantic Ridge3

In most of the world, a deeper seafloor would not make much difference in the rate of melting, because typically ocean water is warmer near the surface and colder below. But Greenland is exactly the opposite. Surface water down to a depth of almost a thousand feet (300 meters) comes mostly from Arctic river runoff. This thick layer of frigid, fresher water is only 33 to 34 degrees Fahrenheit (1 degree Celsius). Below it is a saltier layer of warmer ocean water. This layer is currently more than 5 degrees F (3 degrees C) warmer than the surface layer, and climate models predict its temperature could increase another 3.6 degrees F (2 degrees C) by the end of this century.

About 90 percent of Greenland’s glaciers flow into the ocean, including the newly mapped ones. In generating estimates of how fast these glaciers are likely to melt, researchers have relied on older maps of seafloor depth that show the glaciers flowing into shallow, cold seas. The new study shows that the older maps were wrong.

“While we expected to find deeper fjords than previous maps showed, the differences are huge,” said Eric Rignot of UCI and JPL, lead author of a paper on the research. “They are measured in hundreds of meters, even one kilometer [3,300 feet] in one place.” The difference means that the glaciers actually reach deeper, warmer waters, making them more vulnerable to faster melting as the oceans warm.

Co-author Ian Fenty of JPL noted that earlier maps were based on sparse measurements mostly collected several miles offshore. Mapmakers assumed that the ocean floor sloped upward as it got nearer the coast. That’s a reasonable supposition, but it’s proving to be incorrect around Greenland.

Rignot and Fenty are co-investigators in NASA’s five-year Oceans Melting Greenland (OMG) field campaign, which is creating similar charts of the seafloor for the entire Greenland coastline. Fenty said that OMG’s first mapping cruise last summer found similar results. “Almost every glacier that we visited was in waters that were far, far deeper than the maps showed.”

The researchers also found that besides being deeper overall, the seafloor depth is highly variable. For example, the new map revealed one pair of side-by-side glaciers whose bottom depths vary by about 1,500 feet (500 meters). “These data help us better interpret why some glaciers have reacted to ocean warming while others have not,” Rignot said.

The lack of detailed maps has hampered climate modelers like Fenty who are attempting to predict the melting of the glaciers and their contribution to global sea level rise. “The first time I looked at this area and saw how few data were available, I just threw my hands up,” Fenty said. “If you don’t know the seafloor depth, you can’t do a meaningful simulation of the ocean circulation.”

BREAKING NEWS: Volcanoes Responsible for Climate Change Through Much of Earth’s History

A new study in the April 22 edition of the journal ‘Science’, reveals that volcanic activity associated with the plate-tectonic movement of continents may be responsible for climatic shifts from hot to cold throughout much of Earth’s history. The study, led by researchers at The University of Texas at Austin Jackson School of Geosciences, addresses why Earth has fluctuated from periods when the planet was covered in ice to times when polar regions were ice-free.

volcanic arc

Lead researcher Ryan McKenzie said the team found that periods when volcanoes along continental arcs were more active coincided with warmer trends over the past 720 million years. Conversely, periods when continental arc volcanoes were less active coincided with colder, or cooling trends.

For this study, researchers looked at the uranium-lead crystallization ages of the mineral zircon, which is largely created during continental volcanic arc activity. They looked at data for roughly 120,000 zircon grains from thousands of samples across the globe.

zircon and mantle

Zircon is often associated with mantle plumes. If the zircon Hf model age is very close to its formation age (zircon U–Pb) – the magma could be subsequent of a depleted mantle plume. On the other hand, if the zircon Hf model age is older than its formation age, it can be concluded that the magma was derived from enriched mantle sources or was contaminated by crustal materials.

“We’re looking at changes in zircon production on various continents throughout Earth’s history and seeing how the changes correspond with the various cooling and warming trends,” McKenzie said. “Ultimately, we find that during intervals of high zircon production we have warming trends, and as zircon production diminishes, we see a shift into our cooling trends.”

equation-mantle plumes

New Equation:
Increase Charged Particles → Decreased Magnetic Field → Increase Outer Core Convection → Increase of Mantle Plumes → Increase in Earthquake and Volcanoes → Cools Mantle and Outer Core → Return of Outer Core Convection (Mitch Battros – July 2012)

One question unanswered in recent climate change debates, is what caused the fluctuations in CO2 observed in the geologic record. Other theories have suggested that geological forces such as mountain building have, at different times in the planet’s history, introduced large amounts of new material to the Earth’s surface, and weathering of that material has drawn CO2 out of the atmosphere.

warming-cooling-trends4

Using nearly 200 published studies and their own fieldwork and data, researchers created a global database to reconstruct the volcanic history of continental margins over the past 720 million years.

“We studied sedimentary basins next to former volcanic arcs, which were eroded away over hundreds of millions of years,” said co-author Brian Horton, a professor in the Jackson School’s Department of Geological Sciences. “The distinguishing part of our study is that we looked at a very long geologic record – 720 million years – through multiple warming and cooling trends.”

The cooling periods tended to correlate with the assembly of Earth’s supercontinents, which was a time of diminished continental volcanism, Horton said. The warming periods correlated with continental breakup, a time of enhanced continental volcanism.

Shifting Jet Stream and Ocean Currents Cause of Extreme Weather

Disastrous floods in the Balkans two years ago are likely linked to the temporary slowdown of portions of Earth’s jet stream. Jet Stream patterns circling the globe in the form of large oscillating waves between the Equator and the North Pole, along with shifting ocean currents have caused extreme weather events over Bosnia and Herzegovina, Serbia and Croatia that poured out record amounts of rain.

shifing jet stream and ocean currents_m

The study adds evidence that planetary wave resonance is a key mechanism for causing extreme weather event. Further, the scientists showed that extreme rainfall events are strongly increasing in certain geological areas, in this case over the Balkans.

“We were surprised to see how long the weather system that led to this recent flooding stayed over the region,” says Lisa Stadtherr from the Potsdam Institute for Climate Impact Research (PIK), lead-author of the study to be published in Science Advances. “Day after day the rain was soaking the soil until it was saturated, which lead to the flooding that reportedly caused several dozen casualties and 3.5 billion Euro of damages.”

equation 1998

Equation:
Sunspots → Solar Flares (charged particles) → Magnetic Field Shift → Shifting Ocean and Jet Stream Currents → Extreme Weather and Human Disruption (mitch battros 1998)

While the mean daily rainfall in the Balkans has increased only a little since 1950, the intensity of the strongest rainfall events rose by one third, the scientists found. In May 2014, daily rainfall amounts were locally bigger than ever before in the observed period. The frequency of such potentially devastating extremes in the Balkans, though they are still rare, doubled over the past sixty years.

convergence_zone

There was a similar situation in 1977 in Germany, resulting in the “Elbe” flooding. “This is worrisome because we’re seeing increasing extreme rainfall in many parts of the globe,” says co-author and PIK project head Dim Coumou. “The changes over the Balkan are substantially larger than those expected from simple warming of the air.” Regional temperatures rose by one degree since the middle of the past century, and the increased water holding capacity of warmer air intensifies heavy rainfall by about 7 percent per degree of warming. “Yet the observed rainfall changes in the Balkans are roughly five times that much – hence other factors must have come into play.”

This mechanism has first been put forward by PIK scientist Vladimir Petoukhov only a few years ago, opening a new branch of research; he is co-author of the present study. The scientists produced a video to explain the mechanism which might be a decisive factor for creating extreme weather events in summer in general. (actually by Mitch Battros in 1998)

equation 1998

“Our findings provide more evidence that planetary waves cause extreme weather events,” says co-author Stefan Rahmstorf, chair of PIK’s research team. “When such atmospheric waves start to oscillate this can have serious impacts for people on the ground. I am concerned this current climate cycle may be creating conditions more favorable for this kind of fluctuation.”

 

BREAKING NEWS: Ecuador 7.8 Mag. Earthquake – Death Toll Jumps to 233; More Than 1,500 Wounded

The catastrophic earthquake that destroyed buildings in Ecuador on Saturday became far more devastating Sunday, when the death toll rose to 233 — and it’s expected to rise.

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Another 1,500 people were injured, said Ricardo Peñaherrera of Ecuador’s national emergency management office.

“It was the worst experience of my life,” survivor Jose Meregildo said Sunday about the tremors that violently shook his house in Guayaquil, 300 miles away from the quake’s epicenter.

ecuador-earthquake

“Everybody in my neighborhood was screaming saying it was going to be the end of the world. Residents remain on the streets for fear of aftershocks in Pedernales on April 17.

ecuador-quake04-17-2016

People make their way through debris from a collapsed building in Pedernales on Sunday, April 17. A magnitude-7.8 quake struck off Ecuador’s central coast on Saturday, April 16, flattening buildings and buckling highways. It’s the deadliest quake to strike the South

The magnitude-7.8 earthquake hit Saturday night as it buckled homes and knocked out power in Guayaquil, Ecuador’s most populous city, authorities said. Emergency officials recovered one body from the scene of a bridge collapse there.

ecuador-quake-04

“Many highways are in bad shape, especially in the mountainous area because it has been raining recently due to (the) El Niño weather phenomenon.”

Vice President Jorge Glas had said earlier the death toll is expected to rise.

A state of emergency is in effect for six provinces — Guayas, Manabi, Santo Domingo, Los Rios, Esmeraldas and Galapagos. Authorities urged those who left their homes in coastal areas to return after a tsunami alert was lifted.

During his Sunday prayer, Pope Francis asked for those present to pray for the people affected by the earthquakes in Ecuador and Japan.

“Last night a violent earthquake hit Ecuador, causing numerous victims and great damages,” Francis said. “Let’s pray for those populations, and for those of Japan, where as well there has been some earthquakes in the last days. The help of God and of the brothers give them strength and support.”

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Volcanologists Discover How Magma Bubbles Accumulate

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In 1816, summer failed to make an appearance in central Europe and people were starving. Just a year earlier, the Tambora volcano had erupted in Indonesia, spewing huge amounts of ash and sulphur into the atmosphere. As these particles partly blocked sunlight, cooling the climate, it had a serious impact on the land and the people, even in Switzerland.

magma bubbles

Since then, volcanologists have developed more precise ideas of why super-volcanoes such as Tambora are not only highly explosive but also why they release so much sulphur into the atmosphere.

Gas bubbles tend to accumulate in the upper layers of magma reservoirs, which are only a few kilometers beneath the earth’s surface, building up pressure that can then be abruptly liberated by eruption. These bubbles mainly contain water vapor but also sulphur.

“Such volcanic eruptions can be extremely powerful and spew an enormous amount of ash and sulphur to the surface,” says Andrea Parmigiani, a post-doc in the Institute of Geochemistry and Petrology at ETH Zurich. “We’ve known for some time that gas bubbles play a major role in such events, but we had only been able to speculate on how they accumulate in magma reservoirs.”

Together with other scientists from ETH Zurich and Georgia Institute of Technology (Georgia Tech), the researchers studied the behavior of bubbles with a computer model.

The scientists used theoretical calculations and laboratory experiments to examine in particular how bubbles in crystal-rich and crystal-poor layers of magma reservoirs move buoyantly upward. In many volcanic systems, the magma reservoir consists mainly of two zones: an upper layer consisting of viscous melt with almost no crystals, and a lower layer rich in crystals, but still containing pore space.

When Andrea Parmigiani, Christian Huber and Olivier Bachmann started this project, they thought that the bubbles, as they moved upwards through crystal-rich areas of the magma reservoirs, would dramatically slow down, while they would go faster in the crystal-poor zones.

“Instead, we found that, under volatile-rich conditions, they would ascend much faster in the crystal-rich zones, and accumulate in the melt-rich portions above” says Parmigiani.

Parmigiani explains this as follows: when the proportion of bubbles in the pore space of the crystal-rich layers increases, small individual bubbles coalesce into finger-like channels, displacing the existing highly viscous melt. These finger-like channels allow for a higher vertical gas velocity. The bubbles, however, have to fill at least 10 to 15 % of the pore space.

“If the vapor phase cannot form these channels, individual bubbles are mechanically trapped,” says the earth scientist. As these finger-like channels reach the boundary of the crystal-poor melt, individual, more spherical bubbles detach, and continue their ascent towards the surface. However, the more bubble, the more reduce their migration velocity is.

This is because each bubble creates a return flow of viscous melt around it. When an adjacent bubble feels this return flow, it is slowed down. This process was demonstrated in a laboratory experiment conducted by Parmigiani’s colleagues Salah Faroughi and Christian Huber at Georgia Tech, using water bubbles in a viscous silicone solution.

“Through this mechanism, a large number of gas bubbles can accumulate in the crystal-poor melt under the roof of the magma reservoir. This eventually leads to over-pressurization of the reservoir,” says lead author Parmigiani. And because the bubbles also contain sulphur, this also accumulates, explaining why such a volcano might emit more sulphur than expected based on its composition.

What this means for the explosively of a given volcano is still unclear. “This study focuses primarily on understanding the basic principles of gas flow in magma reservoirs; a direct application to prediction of volcanic behavior remains a question for the future,” says the researcher, adding that existing computer models do not depict the entire magma reservoir, but only a tiny part of it: roughly a square of a few cubic centimeter with a clear boundary between the crystal-poor and crystal-rich layers.

To calculate this small volume, Parmigiani used high-performance computers such as the Euler Cluster at ETH Zurich and a supercomputer at the Swiss National Supercomputing Centre in Lugano.

For the software, the researcher had access to the open-source library Palabos, which he continues to develop in collaboration with researchers from University of Geneva. “This software is particularly suitable for this type of simulation,” says the physicist.

‘Trickle Of Food’ Helped Deep Sea Creatures Survive Asteroid Strike That Wiped Out The Dinosaurs

A team led by experts at Cardiff University has provided new evidence to explain why deep sea creatures were able to survive the catastrophic asteroid strike that wiped out the dinosaurs 65m years ago.

asteroid

Like the dinosaurs themselves, giant marine reptiles, invertebrates and microscopic organisms became extinct after the catastrophic asteroid impact in an immense upheaval of the world’s oceans, yet deep sea creatures managed to survive.

This has puzzled researchers as it is widely believed that the asteroid impact cut off the food supply in the oceans by destroying free-floating algae and bacteria.

However, in a study published in the April issue of the journal Geology, a team led by researchers from Cardiff University’s School of Earth and Ocean Sciences provides strong evidence suggesting that some forms of algae and bacteria were actually living in the aftermath of the asteroid disaster, and that they acted as a constant, sinking, slow trickle of food for creatures living near the seafloor.

The team were able to draw these conclusions by analysing new data from the chemical composition of the fossilised shells of sea surface and seafloor organisms from that period, taken from drilling cores from the ocean floor in the South Atlantic.

This gave the researchers an idea of the flux, or movement, of organic matter from the sea surface to the seafloor in the aftermath of the asteroid strike, and led them to conclude that a slow trickle of food was constantly being delivered to the deep ocean.

Furthermore, the team were able to calculate that the food supply in the ocean was fully restored around 1.7m years after the asteroid strike, which is almost half the original estimates, showing that marine food chains bounced back quicker than originally thought.

Heather Birch, a Cardiff University PhD from the School of Earth and Ocean Sciences who led the study, said: “The global catastrophe that caused the extinction of the dinosaurs also devastated ocean ecosystems. Giant marine reptiles met their end as did various types of invertebrates such as the iconic ammonites.

“Our results show that despite a wave of massive and virtually instantaneous extinctions among the plankton, some types of photosynthesising organisms, such as algae and bacteria, were living in the aftermath of the asteroid strike.

“This provided a slow trickle of food for organisms living near the ocean floor which enabled them to survive the mass extinction, answering one of the outstanding questions that still remained regarding this period of history.

“Even so, it took almost two million years before the deep sea food supply was fully restored as new species evolved to occupy ecological niches vacated by extinct forms.”

Many scientists currently believe that the mass extinction of life on Earth around 65m years ago was caused by a 110km-wide asteroid that hit Mexico’s Yucatán Peninsula. It is believed the debris from impact starved Earth of the Sun’s energy and, once settled, led to greenhouse gases locking in the Sun’s heat and causing temperatures to rise drastically.

This period of darkness followed by soaring heat, known as the Cretaceous-Paleogene boundary, was thought to obliterate almost half of the world’s species.

Scientists also claim that the impact of the asteroid would have filled Earth’s atmosphere with sulphur trioxide, subsequently creating a gas cloud that would have caused a mass amount of sulphuric acid rain to fall in just a few days, making the surface of the ocean too acidic for upper ocean creatures to live.

BREAKING NEWS: Supernova Showered Earth with Radioactive Debris

An international team of scientists has found evidence of a series of massive supernova explosions near our solar system, which showered the Earth with radioactive debris. The scientists found radioactive iron-60 in sediment and crust samples taken from the Pacific, Atlantic and Indian Oceans.

supernova mingus

Some theories suggest cosmic rays from the supernova could have increased cloud cover. The scientists believe the supernova in this case were less than 300 light years away; close enough to be visible during the day and comparable to the brightness of the Moon.

The supernova explosions create many heavy elements and radioactive isotopes which are strewn into the cosmic neighborhood. Although Earth would have been exposed to an increased cosmic ray bombardment, the radiation would have been too weak to cause direct biological damage or trigger mass extinctions.

supernova3

Any iron-60 dating from the Earth’s formation more than four billion years ago has long since disappeared. The iron-60 atoms reached Earth in minuscule quantities and so the team needed extremely sensitive techniques to identify the interstellar iron atoms.

The team from Australia, the University of Vienna in Austria, Hebrew University in Israel, Shimizu Corporation and University of Tokyo, Nihon University and University of Tsukuba in Japan, Senckenberg Collections of Natural History Dresden and Helmholtz-Zentrum Dresden-Rossendorf (HZDR) in Germany, also found evidence of iron-60 from an older supernova around eight million years ago, coinciding with global faunal changes in the late Miocene.

supernova_nedir

The iron-60 was concentrated in a period between 3.2 and 1.7 million years ago, which is relatively recent in astronomical terms, said research leader Dr Anton Wallner from The Australian National University (ANU).

“We were very surprised that there was debris clearly spread across 1.5 million years,” said Dr Wallner, a nuclear physicist in the ANU Research School of Physics and Engineering. “It suggests there were a series of supernova, one after another. “It’s an interesting coincidence that they correspond with when the Earth cooled and moved from the Pliocene into the Pleistocene period.”

stellar-wind

The dating showed the fallout had only occurred in two time periods, 3.2 to 1.7 million years ago and eight million years ago. Current results from TU Munich are in line with these findings.

A possible source of the supernova is an ageing star cluster, which has since moved away from Earth, independent work led by TU Berlin has proposed in a parallel publication. The cluster has no large stars left, suggesting they have already exploded as supernova, throwing out waves of debris.