Study hints that ancient Earth made its own water — geologically

A new study is helping to answer a longstanding question that has recently moved to the forefront of earth science: Did our planet make its own water through geologic processes, or did water come to us via icy comets from the far reaches of the solar system?

The answer is likely “both,” according to researchers at The Ohio State University– and the same amount of water that currently fills the Pacific Ocean could be buried deep inside the planet right now.

At the American Geophysical Union (AGU) meeting on Wednesday, Dec. 17, they report the discovery of a previously unknown geochemical pathway by which the Earth can sequester water in its interior for billions of years and still release small amounts to the surface via plate tectonics, feeding our oceans from within.

In trying to understand the formation of the early Earth, some researchers have suggested that the planet was dry and inhospitable to life until icy comets pelted the earth and deposited water on the surface.

Wendy Panero, associate professor of earth sciences at Ohio State, and doctoral student Jeff Pigott are pursuing a different hypothesis: that Earth was formed with entire oceans of water in its interior, and has been continuously supplying water to the surface via plate tectonics ever since.

Researchers have long accepted that the mantle contains some water, but how much water is a mystery. And, if some geological mechanism has been supplying water to the surface all this time, wouldn’t the mantle have run out of water by now?

Because there’s no way to directly study deep mantle rocks, Panero and Pigott are probing the question with high-pressure physics experiments and computer calculations.

“When we look into the origins of water on Earth, what we’re really asking is, why are we so different than all the other planets?” Panero said. “In this solar system, Earth is unique because we have liquid water on the surface. We’re also the only planet with active plate tectonics. Maybe this water in the mantle is key to plate tectonics, and that’s part of what makes Earth habitable.”

Central to the study is the idea that rocks that appear dry to the human eye can actually contain water–in the form of hydrogen atoms trapped inside natural voids and crystal defects. Oxygen is plentiful in minerals, so when a mineral contains some hydrogen, certain chemical reactions can free the hydrogen to bond with the oxygen and make water.

Stray atoms of hydrogen could make up only a tiny fraction of mantle rock, the researchers explained. Given that the mantle is more than 80 percent of the planet’s total volume, however, those stray atoms add up to a lot of potential water.

In a lab at Ohio State, the researchers compress different minerals that are common to the mantle and subject them to high pressures and temperatures using a diamond anvil cell–a device that squeezes a tiny sample of material between two diamonds and heats it with a laser–to simulate conditions in the deep Earth. They examine how the minerals’ crystal structures change as they are compressed, and use that information to gauge the minerals’ relative capacities for storing hydrogen. Then, they extend their experimental results using computer calculations to uncover the geochemical processes that would enable these minerals to rise through the mantle to the surface–a necessary condition for water to escape into the oceans.

In a paper now submitted to a peer-reviewed academic journal, they reported their recent tests of the mineral bridgmanite, a high-pressure form of olivine. While bridgmanite is the most abundant mineral in the lower mantle, they found that it contains too little hydrogen to play an important role in Earth’s water supply.

Another research group recently found that ringwoodite, another form of olivine, does contain enough hydrogen to make it a good candidate for deep-earth water storage. So Panero and Pigott focused their study on the depth where ringwoodite is found–a place 325-500 miles below the surface that researchers call the “transition zone”–as the most likely region that can hold a planet’s worth of water. From there, the same convection of mantle rock that produces plate tectonics could carry the water to the surface.

One problem: If all the water in ringwoodite is continually drained to the surface via plate tectonics, how could the planet hold any in reserve?

For the research presented at AGU, Panero and Pigott performed new computer calculations of the geochemistry in the lowest portion of the mantle, some 500 miles deep and more. There, another mineral, garnet, emerged as a likely water-carrier–a go-between that could deliver some of the water from ringwoodite down into the otherwise dry lower mantle.

If this scenario is accurate, the Earth may today hold half as much water in its depths as is currently flowing in oceans on the surface, Panero said–an amount that would approximately equal the volume of the Pacific Ocean. This water is continuously cycled through the transition zone as a result of plate tectonics.

“One way to look at this research is that we’re putting constraints on the amount of water that could be down there,” Pigott added.

Panero called the complex relationship between plate tectonics and surface water “one of the great mysteries in the geosciences.” But this new study supports researchers’ growing suspicion that mantle convection somehow regulates the amount of water in the oceans. It also vastly expands the timeline for Earth’s water cycle.

“If all of the Earth’s water is on the surface, that gives us one interpretation of the water cycle, where we can think of water cycling from oceans into the atmosphere and into the groundwater over millions of years,” she said. “But if mantle circulation is also part of the water cycle, the total cycle time for our planet’s water has to be billions of years.”

Study hints that ancient Earth made its own water — geologically

A new study is helping to answer a longstanding question that has recently moved to the forefront of earth science: Did our planet make its own water through geologic processes, or did water come to us via icy comets from the far reaches of the solar system?

The answer is likely “both,” according to researchers at The Ohio State University– and the same amount of water that currently fills the Pacific Ocean could be buried deep inside the planet right now.

At the American Geophysical Union (AGU) meeting on Wednesday, Dec. 17, they report the discovery of a previously unknown geochemical pathway by which the Earth can sequester water in its interior for billions of years and still release small amounts to the surface via plate tectonics, feeding our oceans from within.

In trying to understand the formation of the early Earth, some researchers have suggested that the planet was dry and inhospitable to life until icy comets pelted the earth and deposited water on the surface.

Wendy Panero, associate professor of earth sciences at Ohio State, and doctoral student Jeff Pigott are pursuing a different hypothesis: that Earth was formed with entire oceans of water in its interior, and has been continuously supplying water to the surface via plate tectonics ever since.

Researchers have long accepted that the mantle contains some water, but how much water is a mystery. And, if some geological mechanism has been supplying water to the surface all this time, wouldn’t the mantle have run out of water by now?

Because there’s no way to directly study deep mantle rocks, Panero and Pigott are probing the question with high-pressure physics experiments and computer calculations.

“When we look into the origins of water on Earth, what we’re really asking is, why are we so different than all the other planets?” Panero said. “In this solar system, Earth is unique because we have liquid water on the surface. We’re also the only planet with active plate tectonics. Maybe this water in the mantle is key to plate tectonics, and that’s part of what makes Earth habitable.”

Central to the study is the idea that rocks that appear dry to the human eye can actually contain water–in the form of hydrogen atoms trapped inside natural voids and crystal defects. Oxygen is plentiful in minerals, so when a mineral contains some hydrogen, certain chemical reactions can free the hydrogen to bond with the oxygen and make water.

Stray atoms of hydrogen could make up only a tiny fraction of mantle rock, the researchers explained. Given that the mantle is more than 80 percent of the planet’s total volume, however, those stray atoms add up to a lot of potential water.

In a lab at Ohio State, the researchers compress different minerals that are common to the mantle and subject them to high pressures and temperatures using a diamond anvil cell–a device that squeezes a tiny sample of material between two diamonds and heats it with a laser–to simulate conditions in the deep Earth. They examine how the minerals’ crystal structures change as they are compressed, and use that information to gauge the minerals’ relative capacities for storing hydrogen. Then, they extend their experimental results using computer calculations to uncover the geochemical processes that would enable these minerals to rise through the mantle to the surface–a necessary condition for water to escape into the oceans.

In a paper now submitted to a peer-reviewed academic journal, they reported their recent tests of the mineral bridgmanite, a high-pressure form of olivine. While bridgmanite is the most abundant mineral in the lower mantle, they found that it contains too little hydrogen to play an important role in Earth’s water supply.

Another research group recently found that ringwoodite, another form of olivine, does contain enough hydrogen to make it a good candidate for deep-earth water storage. So Panero and Pigott focused their study on the depth where ringwoodite is found–a place 325-500 miles below the surface that researchers call the “transition zone”–as the most likely region that can hold a planet’s worth of water. From there, the same convection of mantle rock that produces plate tectonics could carry the water to the surface.

One problem: If all the water in ringwoodite is continually drained to the surface via plate tectonics, how could the planet hold any in reserve?

For the research presented at AGU, Panero and Pigott performed new computer calculations of the geochemistry in the lowest portion of the mantle, some 500 miles deep and more. There, another mineral, garnet, emerged as a likely water-carrier–a go-between that could deliver some of the water from ringwoodite down into the otherwise dry lower mantle.

If this scenario is accurate, the Earth may today hold half as much water in its depths as is currently flowing in oceans on the surface, Panero said–an amount that would approximately equal the volume of the Pacific Ocean. This water is continuously cycled through the transition zone as a result of plate tectonics.

“One way to look at this research is that we’re putting constraints on the amount of water that could be down there,” Pigott added.

Panero called the complex relationship between plate tectonics and surface water “one of the great mysteries in the geosciences.” But this new study supports researchers’ growing suspicion that mantle convection somehow regulates the amount of water in the oceans. It also vastly expands the timeline for Earth’s water cycle.

“If all of the Earth’s water is on the surface, that gives us one interpretation of the water cycle, where we can think of water cycling from oceans into the atmosphere and into the groundwater over millions of years,” she said. “But if mantle circulation is also part of the water cycle, the total cycle time for our planet’s water has to be billions of years.”

Volcano hazards and the role of westerly wind bursts in El Niño

On June 27, lava from Kīlauea, an active volcano on the island of Hawai'i, began flowing to the northeast, threatening the residents in a community in the District of Puna. -  USGS
On June 27, lava from Kīlauea, an active volcano on the island of Hawai’i, began flowing to the northeast, threatening the residents in a community in the District of Puna. – USGS

On 27 June, lava from Kīlauea, an active volcano on the island of Hawai’i, began flowing to the northeast, threatening the residents in Pāhoa, a community in the District of Puna, as well as the only highway accessible to this area. Scientists from the U.S. Geological Survey’s Hawaiian Volcano Observatory (HVO) and the Hawai’i County Civil Defense have been monitoring the volcano’s lava flow and communicating with affected residents through public meetings since 24 August. Eos recently spoke with Michael Poland, a geophysicist at HVO and a member of the Eos Editorial Advisory Board, to discuss how he and his colleagues communicated this threat to the public.

Drilling a Small Basaltic Volcano to Reveal Potential Hazards


Drilling into the Rangitoto Island Volcano in the Auckland Volcanic Field in New Zealand offers insight into a small monogenetic volcano, and may improve understanding of future hazards.

From AGU’s journals: El Niño fades without westerly wind bursts

The warm and wet winter of 1997 brought California floods, Florida tornadoes, and an ice storm in the American northeast, prompting climatologists to dub it the El Niño of the century. Earlier this year, climate scientists thought the coming winter might bring similar extremes, as equatorial Pacific Ocean conditions resembled those seen in early 1997. But the signals weakened by summer, and the El Niño predictions were downgraded. Menkes et al. used simulations to examine the differences between the two years.

The El Niño-Southern Oscillation is defined by abnormally warm sea surface temperatures in the eastern Pacific Ocean and weaker than usual trade winds. In a typical year, southeast trade winds push surface water toward the western Pacific “warm pool”–a region essential to Earth’s climate. The trade winds dramatically weaken or even reverse in El Niño years, and the warm pool extends its reach east.

Scientists have struggled to predict El Niño due to irregularities in the shape, amplitude, and timing of the surges of warm water. Previous studies suggested that short-lived westerly wind pulses (i.e. one to two weeks long) could contribute to this irregularity by triggering and sustaining El Niño events.

To understand the vanishing 2014 El Niño, the authors used computer simulations and examined the wind’s role. The researchers find pronounced differences between 1997 and 2014. Both years saw strong westerly wind events between January and March, but those disappeared this year as spring approached. In contrast, the westerly winds persisted through summer in 1997.

In the past, it was thought that westerly wind pulses were three times as likely to form if the warm pool extended east of the dateline. That did not occur this year. The team says their analysis shows that El Niño’s strength might depend on these short-lived and possibly unpredictable pulses.

###

The American Geophysical Union is dedicated to advancing the Earth and space sciences for the benefit of humanity through its scholarly publications, conferences, and outreach programs. AGU is a not-for-profit, professional, scientific organization representing more than 62,000 members in 144 countries. Join our conversation on Facebook, Twitter, YouTube, and other social media channels.

Volcano hazards and the role of westerly wind bursts in El Niño

On June 27, lava from Kīlauea, an active volcano on the island of Hawai'i, began flowing to the northeast, threatening the residents in a community in the District of Puna. -  USGS
On June 27, lava from Kīlauea, an active volcano on the island of Hawai’i, began flowing to the northeast, threatening the residents in a community in the District of Puna. – USGS

On 27 June, lava from Kīlauea, an active volcano on the island of Hawai’i, began flowing to the northeast, threatening the residents in Pāhoa, a community in the District of Puna, as well as the only highway accessible to this area. Scientists from the U.S. Geological Survey’s Hawaiian Volcano Observatory (HVO) and the Hawai’i County Civil Defense have been monitoring the volcano’s lava flow and communicating with affected residents through public meetings since 24 August. Eos recently spoke with Michael Poland, a geophysicist at HVO and a member of the Eos Editorial Advisory Board, to discuss how he and his colleagues communicated this threat to the public.

Drilling a Small Basaltic Volcano to Reveal Potential Hazards


Drilling into the Rangitoto Island Volcano in the Auckland Volcanic Field in New Zealand offers insight into a small monogenetic volcano, and may improve understanding of future hazards.

From AGU’s journals: El Niño fades without westerly wind bursts

The warm and wet winter of 1997 brought California floods, Florida tornadoes, and an ice storm in the American northeast, prompting climatologists to dub it the El Niño of the century. Earlier this year, climate scientists thought the coming winter might bring similar extremes, as equatorial Pacific Ocean conditions resembled those seen in early 1997. But the signals weakened by summer, and the El Niño predictions were downgraded. Menkes et al. used simulations to examine the differences between the two years.

The El Niño-Southern Oscillation is defined by abnormally warm sea surface temperatures in the eastern Pacific Ocean and weaker than usual trade winds. In a typical year, southeast trade winds push surface water toward the western Pacific “warm pool”–a region essential to Earth’s climate. The trade winds dramatically weaken or even reverse in El Niño years, and the warm pool extends its reach east.

Scientists have struggled to predict El Niño due to irregularities in the shape, amplitude, and timing of the surges of warm water. Previous studies suggested that short-lived westerly wind pulses (i.e. one to two weeks long) could contribute to this irregularity by triggering and sustaining El Niño events.

To understand the vanishing 2014 El Niño, the authors used computer simulations and examined the wind’s role. The researchers find pronounced differences between 1997 and 2014. Both years saw strong westerly wind events between January and March, but those disappeared this year as spring approached. In contrast, the westerly winds persisted through summer in 1997.

In the past, it was thought that westerly wind pulses were three times as likely to form if the warm pool extended east of the dateline. That did not occur this year. The team says their analysis shows that El Niño’s strength might depend on these short-lived and possibly unpredictable pulses.

###

The American Geophysical Union is dedicated to advancing the Earth and space sciences for the benefit of humanity through its scholarly publications, conferences, and outreach programs. AGU is a not-for-profit, professional, scientific organization representing more than 62,000 members in 144 countries. Join our conversation on Facebook, Twitter, YouTube, and other social media channels.

Ancient shellfish remains rewrite 10,000-year history of El Nino cycles

The middens are ancient dumping sites that typically contain a mix of mollusk shells, fish and bird bones, ceramics, cloth, charcoal, maize and other plants. -  M. Carré / Univ. of Montpellier
The middens are ancient dumping sites that typically contain a mix of mollusk shells, fish and bird bones, ceramics, cloth, charcoal, maize and other plants. – M. Carré / Univ. of Montpellier

The planet’s largest and most powerful driver of climate changes from one year to the next, the El Niño Southern Oscillation in the tropical Pacific Ocean, was widely thought to have been weaker in ancient times because of a different configuration of the Earth’s orbit. But scientists analyzing 25-foot piles of ancient shells have found that the El Niños 10,000 years ago were as strong and frequent as the ones we experience today.

The results, from the University of Washington and University of Montpellier, question how well computer models can reproduce historical El Niño cycles, or predict how they could change under future climates. The paper is now online and will appear in an upcoming issue of Science.

“We thought we understood what influences the El Niño mode of climate variation, and we’ve been able to show that we actually don’t understand it very well,” said Julian Sachs, a UW professor of oceanography.

The ancient shellfish feasts also upend a widely held interpretation of past climate.

“Our data contradicts the hypothesis that El Niño activity was very reduced 10,000 years ago, and then slowly increased since then,” said first author Matthieu Carré, who did the research as a UW postdoctoral researcher and now holds a faculty position at the University of Montpellier in France.

In 2007, while at the UW-based Joint Institute for the Study of the Atmosphere and Ocean, Carré accompanied archaeologists to seven sites in coastal Peru. Together they sampled 25-foot-tall piles of shells from Mesodesma donacium clams eaten and then discarded over centuries into piles that archaeologists call middens.

While in graduate school, Carré had developed a technique to analyze shell layers to get ocean temperatures, using carbon dating of charcoal from fires to get the year, and the ratio of oxygen isotopes in the growth layers to get the water temperatures as the shell was forming.

The shells provide 1- to 3-year-long records of monthly temperature of the Pacific Ocean along the coast of Peru. Combining layers of shells from each site gives water temperatures for intervals spanning 100 to 1,000 years during the past 10,000 years.

The new record shows that 10,000 years ago the El Niño cycles were strong, contradicting the current leading interpretations. Roughly 7,000 years ago the shells show a shift to the central Pacific of the most severe El Niño impacts, followed by a lull in the strength and occurrence of El Niño from about 6,000 to 4,000 years ago.

One possible explanation for the surprising finding of a strong El Niño 10,000 years ago was that some other factor was compensating for the dampening effect expected from cyclical changes in Earth’s orbit around the sun during that period.

“The best candidate is the polar ice sheet, which was melting very fast in this period and may have increased El Niño activity by changing ocean currents,” Carré said.

Around 6,000 years ago most of the ice age floes would have finished melting, so the effect of Earth’s orbital geometry might have taken over then to cause the period of weak El Niños.

In previous studies, warm-water shells and evidence of flooding in Andean lakes had been interpreted as signs of a much weaker El Niño around 10,000 years ago.

The new data is more reliable, Carré said, for three reasons: the Peruvian coast is strongly affected by El Niño; the shells record ocean temperature, which is the most important parameter for the El Niño cycles; and the ability to record seasonal changes, the timescale at which El Niño can be observed.

“Climate models and a variety of datasets had concluded that El Niños were essentially nonexistent, did not occur, before 6,000 to 8,000 years ago,” Sachs said. “Our results very clearly show that this is not the case, and suggest that current understanding of the El Niño system is incomplete.

Ancient shellfish remains rewrite 10,000-year history of El Nino cycles

The middens are ancient dumping sites that typically contain a mix of mollusk shells, fish and bird bones, ceramics, cloth, charcoal, maize and other plants. -  M. Carré / Univ. of Montpellier
The middens are ancient dumping sites that typically contain a mix of mollusk shells, fish and bird bones, ceramics, cloth, charcoal, maize and other plants. – M. Carré / Univ. of Montpellier

The planet’s largest and most powerful driver of climate changes from one year to the next, the El Niño Southern Oscillation in the tropical Pacific Ocean, was widely thought to have been weaker in ancient times because of a different configuration of the Earth’s orbit. But scientists analyzing 25-foot piles of ancient shells have found that the El Niños 10,000 years ago were as strong and frequent as the ones we experience today.

The results, from the University of Washington and University of Montpellier, question how well computer models can reproduce historical El Niño cycles, or predict how they could change under future climates. The paper is now online and will appear in an upcoming issue of Science.

“We thought we understood what influences the El Niño mode of climate variation, and we’ve been able to show that we actually don’t understand it very well,” said Julian Sachs, a UW professor of oceanography.

The ancient shellfish feasts also upend a widely held interpretation of past climate.

“Our data contradicts the hypothesis that El Niño activity was very reduced 10,000 years ago, and then slowly increased since then,” said first author Matthieu Carré, who did the research as a UW postdoctoral researcher and now holds a faculty position at the University of Montpellier in France.

In 2007, while at the UW-based Joint Institute for the Study of the Atmosphere and Ocean, Carré accompanied archaeologists to seven sites in coastal Peru. Together they sampled 25-foot-tall piles of shells from Mesodesma donacium clams eaten and then discarded over centuries into piles that archaeologists call middens.

While in graduate school, Carré had developed a technique to analyze shell layers to get ocean temperatures, using carbon dating of charcoal from fires to get the year, and the ratio of oxygen isotopes in the growth layers to get the water temperatures as the shell was forming.

The shells provide 1- to 3-year-long records of monthly temperature of the Pacific Ocean along the coast of Peru. Combining layers of shells from each site gives water temperatures for intervals spanning 100 to 1,000 years during the past 10,000 years.

The new record shows that 10,000 years ago the El Niño cycles were strong, contradicting the current leading interpretations. Roughly 7,000 years ago the shells show a shift to the central Pacific of the most severe El Niño impacts, followed by a lull in the strength and occurrence of El Niño from about 6,000 to 4,000 years ago.

One possible explanation for the surprising finding of a strong El Niño 10,000 years ago was that some other factor was compensating for the dampening effect expected from cyclical changes in Earth’s orbit around the sun during that period.

“The best candidate is the polar ice sheet, which was melting very fast in this period and may have increased El Niño activity by changing ocean currents,” Carré said.

Around 6,000 years ago most of the ice age floes would have finished melting, so the effect of Earth’s orbital geometry might have taken over then to cause the period of weak El Niños.

In previous studies, warm-water shells and evidence of flooding in Andean lakes had been interpreted as signs of a much weaker El Niño around 10,000 years ago.

The new data is more reliable, Carré said, for three reasons: the Peruvian coast is strongly affected by El Niño; the shells record ocean temperature, which is the most important parameter for the El Niño cycles; and the ability to record seasonal changes, the timescale at which El Niño can be observed.

“Climate models and a variety of datasets had concluded that El Niños were essentially nonexistent, did not occur, before 6,000 to 8,000 years ago,” Sachs said. “Our results very clearly show that this is not the case, and suggest that current understanding of the El Niño system is incomplete.

Research provides new theory on cause of ice age 2.6 million years ago

New research published today (Friday 27th June 2014) in the journal Nature Scientific Reports has provided a major new theory on the cause of the ice age that covered large parts of the Northern Hemisphere 2.6 million years ago.

The study, co-authored by Dr Thomas Stevens, from the Department of Geography at Royal Holloway, University of London, found a previously unknown mechanism by which the joining of North and South America changed the salinity of the Pacific Ocean and caused major ice sheet growth across the Northern Hemisphere.

The change in salinity encouraged sea ice to form which in turn created a change in wind patterns, leading to intensified monsoons. These provided moisture that caused an increase in snowfall and the growth of major ice sheets, some of which reached 3km thick.

The team of researchers analysed deposits of wind-blown dust called red clay that accumulated between six million and two and a half million years ago in north central China, adjacent to the Tibetan plateau, and used them to reconstruct changing monsoon precipitation and temperature.

“Until now, the cause of the Quaternary ice age had been a hotly debated topic”, said Dr Stevens. “Our findings suggest a significant link between ice sheet growth, the monsoon and the closing of the Panama Seaway, as North and South America drifted closer together. This provides us with a major new theory on the origins of the ice age, and ultimately our current climate system.”

Surprisingly, the researchers found there was a strengthening of the monsoon during global cooling, instead of the intense rainfall normally associated with warmer climates.

Dr Stevens added: “This led us to discover a previously unknown interaction between plate tectonic movements in the Americas and dramatic changes in global temperature. The intensified monsoons created a positive feedback cycle, promoting more global cooling, more sea ice and even stronger precipitation, culminating in the spread of huge glaciers across the Northern Hemisphere.”

Research provides new theory on cause of ice age 2.6 million years ago

New research published today (Friday 27th June 2014) in the journal Nature Scientific Reports has provided a major new theory on the cause of the ice age that covered large parts of the Northern Hemisphere 2.6 million years ago.

The study, co-authored by Dr Thomas Stevens, from the Department of Geography at Royal Holloway, University of London, found a previously unknown mechanism by which the joining of North and South America changed the salinity of the Pacific Ocean and caused major ice sheet growth across the Northern Hemisphere.

The change in salinity encouraged sea ice to form which in turn created a change in wind patterns, leading to intensified monsoons. These provided moisture that caused an increase in snowfall and the growth of major ice sheets, some of which reached 3km thick.

The team of researchers analysed deposits of wind-blown dust called red clay that accumulated between six million and two and a half million years ago in north central China, adjacent to the Tibetan plateau, and used them to reconstruct changing monsoon precipitation and temperature.

“Until now, the cause of the Quaternary ice age had been a hotly debated topic”, said Dr Stevens. “Our findings suggest a significant link between ice sheet growth, the monsoon and the closing of the Panama Seaway, as North and South America drifted closer together. This provides us with a major new theory on the origins of the ice age, and ultimately our current climate system.”

Surprisingly, the researchers found there was a strengthening of the monsoon during global cooling, instead of the intense rainfall normally associated with warmer climates.

Dr Stevens added: “This led us to discover a previously unknown interaction between plate tectonic movements in the Americas and dramatic changes in global temperature. The intensified monsoons created a positive feedback cycle, promoting more global cooling, more sea ice and even stronger precipitation, culminating in the spread of huge glaciers across the Northern Hemisphere.”

How productive are the ore factories in the deep sea?

About ten years after the first moon landing, scientists on earth made a discovery that proved that our home planet still holds a lot of surprises in store for us. Looking through the portholes of the submersible ALVIN near the bottom of the Pacific Ocean in 1979, American scientists saw for the first time chimneys, several meters tall, from which black water at about 300 degrees and saturated with minerals shot out. What we have found out since then: These “black smokers”, also called hydrothermal vents, exist in all oceans. They occur along the boundaries of tectonic plates along the submarine volcanic chains. However, to date many details of these systems remain unexplained.

One question that has long and intensively been discussed in research is: Where and how deep does seawater penetrate into the seafloor to take up heat and minerals before it leaves the ocean floor at hydrothermal vents? This is of enormous importance for both, the cooling of the underwater volcanoes as well as for the amount of materials dissolved. Using a complex 3-D computer model, scientists at GEOMAR Helmholtz Centre for Ocean Research Kiel were now able to understand the paths of the water toward the black smokers. The study appears in the current issue of the world-renowned scientific journal “Nature“.

In general, it is well known that seawater penetrates into the Earth’s interior through cracks and crevices along the plate boundaries. The seawater is heated by the magma; the hot water rises again, leaches metals and other elements from the ground and is released as a black colored solution. “However, in detail it is somewhat unclear whether the water enters the ocean floor in the immediate vicinity of the vents and flows upward immediately, or whether it travels long distances underground before venting,” explains Dr. Jörg Hasenclever from GEOMAR.

This question is not only important for the fundamental understanding of processes on our planet. It also has very practical implications. Some of the materials leached from the underground are deposited on the seabed and form ore deposits that may be of economically interest. There is a major debate, however, how large the resource potential of these deposits might be. “When we know which paths the water travels underground, we can better estimate the quantities of materials released by black smokers over thousands of years,” says Hasenclever.

Hasenclever and his colleagues have used for the first time a high-resolution computer model of the seafloor to simulate a six kilometer long and deep, and 16 kilometer wide section of a mid-ocean ridge in the Pacific. Among the data used by the model was the heat distribution in the oceanic crust, which is known from seismic studies. In addition, the model also considered the permeability of the rock and the special physical properties of water.

The simulation required several weeks of computing time. The result: “There are actually two different flow paths – about half the water seeps in near the vents, where the ground is very warm. The other half seeps in at greater distances and migrates for kilometers through the seafloor before exiting years later.” Thus, the current study partially confirmed results from a computer model, which were published in 2008 in the scientific journal “Science”. “However, the colleagues back then were able to simulate only a much smaller region of the ocean floor and therefore identified only the short paths near the black smokers,” says Hasenclever.

The current study is based on fundamental work on the modeling of the seafloor, which was conducted in the group of Professor Lars Rüpke within the framework of the Kiel Cluster of Excellence “The Future Ocean”. It provides scientists worldwide with the basis for further investigations to see how much ore is actually on and in the seabed, and whether or not deep-sea mining on a large scale could ever become worthwhile. “So far, we only know the surface of the ore deposits at hydrothermal vents. Nobody knows exactly how much metal is really deposited there. All the discussions about the pros and cons of deep-sea ore mining are based on a very thin database,” says co-author Prof. Dr. Colin Devey from GEOMAR. “We need to collect a lot more data on hydrothermal systems before we can make reliable statements”.

How productive are the ore factories in the deep sea?

About ten years after the first moon landing, scientists on earth made a discovery that proved that our home planet still holds a lot of surprises in store for us. Looking through the portholes of the submersible ALVIN near the bottom of the Pacific Ocean in 1979, American scientists saw for the first time chimneys, several meters tall, from which black water at about 300 degrees and saturated with minerals shot out. What we have found out since then: These “black smokers”, also called hydrothermal vents, exist in all oceans. They occur along the boundaries of tectonic plates along the submarine volcanic chains. However, to date many details of these systems remain unexplained.

One question that has long and intensively been discussed in research is: Where and how deep does seawater penetrate into the seafloor to take up heat and minerals before it leaves the ocean floor at hydrothermal vents? This is of enormous importance for both, the cooling of the underwater volcanoes as well as for the amount of materials dissolved. Using a complex 3-D computer model, scientists at GEOMAR Helmholtz Centre for Ocean Research Kiel were now able to understand the paths of the water toward the black smokers. The study appears in the current issue of the world-renowned scientific journal “Nature“.

In general, it is well known that seawater penetrates into the Earth’s interior through cracks and crevices along the plate boundaries. The seawater is heated by the magma; the hot water rises again, leaches metals and other elements from the ground and is released as a black colored solution. “However, in detail it is somewhat unclear whether the water enters the ocean floor in the immediate vicinity of the vents and flows upward immediately, or whether it travels long distances underground before venting,” explains Dr. Jörg Hasenclever from GEOMAR.

This question is not only important for the fundamental understanding of processes on our planet. It also has very practical implications. Some of the materials leached from the underground are deposited on the seabed and form ore deposits that may be of economically interest. There is a major debate, however, how large the resource potential of these deposits might be. “When we know which paths the water travels underground, we can better estimate the quantities of materials released by black smokers over thousands of years,” says Hasenclever.

Hasenclever and his colleagues have used for the first time a high-resolution computer model of the seafloor to simulate a six kilometer long and deep, and 16 kilometer wide section of a mid-ocean ridge in the Pacific. Among the data used by the model was the heat distribution in the oceanic crust, which is known from seismic studies. In addition, the model also considered the permeability of the rock and the special physical properties of water.

The simulation required several weeks of computing time. The result: “There are actually two different flow paths – about half the water seeps in near the vents, where the ground is very warm. The other half seeps in at greater distances and migrates for kilometers through the seafloor before exiting years later.” Thus, the current study partially confirmed results from a computer model, which were published in 2008 in the scientific journal “Science”. “However, the colleagues back then were able to simulate only a much smaller region of the ocean floor and therefore identified only the short paths near the black smokers,” says Hasenclever.

The current study is based on fundamental work on the modeling of the seafloor, which was conducted in the group of Professor Lars Rüpke within the framework of the Kiel Cluster of Excellence “The Future Ocean”. It provides scientists worldwide with the basis for further investigations to see how much ore is actually on and in the seabed, and whether or not deep-sea mining on a large scale could ever become worthwhile. “So far, we only know the surface of the ore deposits at hydrothermal vents. Nobody knows exactly how much metal is really deposited there. All the discussions about the pros and cons of deep-sea ore mining are based on a very thin database,” says co-author Prof. Dr. Colin Devey from GEOMAR. “We need to collect a lot more data on hydrothermal systems before we can make reliable statements”.