Study explains connection between Hawaii’s dueling volcanoes

A plume of magmatic gases rises from a vent that formed in 2008 within Halema'uma'u Crater, which is located within Kilauea's summit caldera. -  CREDIT: M. Poland/USGS HVO
A plume of magmatic gases rises from a vent that formed in 2008 within Halema’uma’u Crater, which is located within Kilauea’s summit caldera. – CREDIT: M. Poland/USGS HVO

A new Rice University-led study finds that a deep connection about 50 miles underground can explain the enigmatic behavior of two of Earth’s most notable volcanoes, Hawaii’s Mauna Loa and Kilauea. The study, the first to model paired volcano interactions, explains how a link in Earth’s upper mantle could account for Kilauea and Mauna Loa’s competition for the same deep magma supply and their simultaneous “inflation,” or bulging upward, during the past decade.

The study appears in the November issue of Nature Geoscience.

The research offers the first plausible model that can explain both the opposing long-term eruptive patterns at Mauna Loa and Kilauea — when one is active the other is quiet — as well as the episode in 2003-2007 when GPS records showed that each bulged notably due to the pressure of rising magma. The study was conducted by scientists at Rice University, the University of Hawaii, the U.S. Geological Survey (USGS) and the Carnegie Institution of Washington.

“We know both volcanoes are fed by the same hot spot, and over the past decade we’ve observed simultaneous inflation, which we interpret to be the consequence of increased pressure of the magma source that feeds them,” said lead author Helge Gonnermann, assistant professor of Earth science at Rice University. “We also know there are subtle chemical differences in the lava that each erupts, which means each has its own plumbing that draws magma from different locations of this deep source.

“In the GPS records, we first see inflation at Kilauea and then about a half a year later at Mauna Loa,” he said. “Our hypothesis is that the pressure is transmitted slowly through a partially molten and thereby porous region of the asthenosphere, which would account for the simultaneous inflation and the lag time in inflation. Because changes in pore pressure are transmitted between both volcanoes at a faster rate than the rate of magma flow within the porous region, this can also explain how both volcanoes are dynamically coupled, while being supplied by different parts of the same source region.”

Gonnermann said the transmission of pressure through the permeable rock in the asthenosphere is akin to the processes that cause water and oil to flow through permeable layers of rock in shallower regions of Earth’s crust.

“When we fitted the deformation, which tells us how much a volcano inflates and deflates, and the lava eruption rate at Kilauea, we found that our model could simultaneously match the deformation signal recorded over on Mauna Loa,” said James Foster, co-author and assistant researcher at the University of Hawaii School of Ocean and Earth Science and Technology. “The model also required an increase in the magma supply rate to the deep system that matched very nicely with our interpretations and the increased magma supply suggested by the jump in CO2 emissions that occurred in late 2003.”

Mauna Loa and Kilauea, Earth’s largest and most active volcanoes, respectively, are located about 22 miles apart in the Hawaii Volcanoes National Park on the island of Hawaii. They are among the planet’s most-studied and best-instrumented volcanoes and have been actively monitored by scientists at USGS’s Hawaiian Volcano Observatory (HVO) since 1912. Kilauea has erupted 48 times on HVO’s watch, with a nearly continuous flank eruption since 1983. Mauna Loa has erupted 12 times in the same period, most recently in 1984.

“To continue this research, we submitted a proposal to the National Science Foundation (NSF) earlier this summer to extend our study back in time to cover the last 50 years,” Foster said. “We plan to refine the model to include further details of the magma transport within each volcano and also explore how some known prehistoric events and some hypothetical events at one volcano might impact the other. This work should help improve our understanding of volcanic activity of each volcano.”

Gonnermann said there has been disagreement among Earth scientists about the potential links between adjacent volcanoes, and he is hopeful the new model could be useful in studying other volcanoes like those in Iceland or the Galapagos Islands.

“At this point it is unclear whether Hawaii is unique or whether similar volcano coupling may exist at other locations,” Gonnermann said. “Given time and ongoing advances in volcano monitoring, we can test if similar coupling between adjacent volcanoes exists elsewhere.”

Study explains connection between Hawaii’s dueling volcanoes

A plume of magmatic gases rises from a vent that formed in 2008 within Halema'uma'u Crater, which is located within Kilauea's summit caldera. -  CREDIT: M. Poland/USGS HVO
A plume of magmatic gases rises from a vent that formed in 2008 within Halema’uma’u Crater, which is located within Kilauea’s summit caldera. – CREDIT: M. Poland/USGS HVO

A new Rice University-led study finds that a deep connection about 50 miles underground can explain the enigmatic behavior of two of Earth’s most notable volcanoes, Hawaii’s Mauna Loa and Kilauea. The study, the first to model paired volcano interactions, explains how a link in Earth’s upper mantle could account for Kilauea and Mauna Loa’s competition for the same deep magma supply and their simultaneous “inflation,” or bulging upward, during the past decade.

The study appears in the November issue of Nature Geoscience.

The research offers the first plausible model that can explain both the opposing long-term eruptive patterns at Mauna Loa and Kilauea — when one is active the other is quiet — as well as the episode in 2003-2007 when GPS records showed that each bulged notably due to the pressure of rising magma. The study was conducted by scientists at Rice University, the University of Hawaii, the U.S. Geological Survey (USGS) and the Carnegie Institution of Washington.

“We know both volcanoes are fed by the same hot spot, and over the past decade we’ve observed simultaneous inflation, which we interpret to be the consequence of increased pressure of the magma source that feeds them,” said lead author Helge Gonnermann, assistant professor of Earth science at Rice University. “We also know there are subtle chemical differences in the lava that each erupts, which means each has its own plumbing that draws magma from different locations of this deep source.

“In the GPS records, we first see inflation at Kilauea and then about a half a year later at Mauna Loa,” he said. “Our hypothesis is that the pressure is transmitted slowly through a partially molten and thereby porous region of the asthenosphere, which would account for the simultaneous inflation and the lag time in inflation. Because changes in pore pressure are transmitted between both volcanoes at a faster rate than the rate of magma flow within the porous region, this can also explain how both volcanoes are dynamically coupled, while being supplied by different parts of the same source region.”

Gonnermann said the transmission of pressure through the permeable rock in the asthenosphere is akin to the processes that cause water and oil to flow through permeable layers of rock in shallower regions of Earth’s crust.

“When we fitted the deformation, which tells us how much a volcano inflates and deflates, and the lava eruption rate at Kilauea, we found that our model could simultaneously match the deformation signal recorded over on Mauna Loa,” said James Foster, co-author and assistant researcher at the University of Hawaii School of Ocean and Earth Science and Technology. “The model also required an increase in the magma supply rate to the deep system that matched very nicely with our interpretations and the increased magma supply suggested by the jump in CO2 emissions that occurred in late 2003.”

Mauna Loa and Kilauea, Earth’s largest and most active volcanoes, respectively, are located about 22 miles apart in the Hawaii Volcanoes National Park on the island of Hawaii. They are among the planet’s most-studied and best-instrumented volcanoes and have been actively monitored by scientists at USGS’s Hawaiian Volcano Observatory (HVO) since 1912. Kilauea has erupted 48 times on HVO’s watch, with a nearly continuous flank eruption since 1983. Mauna Loa has erupted 12 times in the same period, most recently in 1984.

“To continue this research, we submitted a proposal to the National Science Foundation (NSF) earlier this summer to extend our study back in time to cover the last 50 years,” Foster said. “We plan to refine the model to include further details of the magma transport within each volcano and also explore how some known prehistoric events and some hypothetical events at one volcano might impact the other. This work should help improve our understanding of volcanic activity of each volcano.”

Gonnermann said there has been disagreement among Earth scientists about the potential links between adjacent volcanoes, and he is hopeful the new model could be useful in studying other volcanoes like those in Iceland or the Galapagos Islands.

“At this point it is unclear whether Hawaii is unique or whether similar volcano coupling may exist at other locations,” Gonnermann said. “Given time and ongoing advances in volcano monitoring, we can test if similar coupling between adjacent volcanoes exists elsewhere.”

Earthquake? Blame it on the rain

The U.S. Geological Survey’s website states it in no uncertain terms: “There is no such thing as ‘earthquake weather.'” Yet, from at least the time of Aristotle, some people have professed links between atmospheric conditions and seismic shaking. For the most part, these hypotheses have not held up under scientific scrutiny and earthquake researchers have set them aside as intriguing but unfounded ideas. However, in the last decade new efforts to identify effects of weather-related, or in some cases climate-related, processes on seismicity have drawn new interest.

Researchers are beginning to take a closer look at the Main Himalayan Thrust in northern India and Nepal, inland regions of Taiwan and seismically active semi-tropical regions like Haiti for evidence of weather-induced seismicity. These groups postulate that tremendous excesses of rainwater falling over short amounts of time may alter the stresses acting on faults, potentially triggering earthquakes to occur sooner than they otherwise would. How will this research affect earthquake preparedness in the future? Read the full story online at http://www.earthmagazine.org/article/blame-it-rain-proposed-links-between-severe-storms-and-earthquakes.

Earthquake? Blame it on the rain

The U.S. Geological Survey’s website states it in no uncertain terms: “There is no such thing as ‘earthquake weather.'” Yet, from at least the time of Aristotle, some people have professed links between atmospheric conditions and seismic shaking. For the most part, these hypotheses have not held up under scientific scrutiny and earthquake researchers have set them aside as intriguing but unfounded ideas. However, in the last decade new efforts to identify effects of weather-related, or in some cases climate-related, processes on seismicity have drawn new interest.

Researchers are beginning to take a closer look at the Main Himalayan Thrust in northern India and Nepal, inland regions of Taiwan and seismically active semi-tropical regions like Haiti for evidence of weather-induced seismicity. These groups postulate that tremendous excesses of rainwater falling over short amounts of time may alter the stresses acting on faults, potentially triggering earthquakes to occur sooner than they otherwise would. How will this research affect earthquake preparedness in the future? Read the full story online at http://www.earthmagazine.org/article/blame-it-rain-proposed-links-between-severe-storms-and-earthquakes.

Rapid changes in the Earth’s core: The magnetic field and gravity from a satellite perspective

Annual to decadal changes in the earth’s magnetic field in a region that stretches from the Atlantic to the Indian Ocean have a close relationship with variations of gravity in this area. From this it can be concluded that outer core processes are reflected in gravity data. This is the result presented by a German-French group of geophysicists in the latest issue of PNAS (Proceedings of the National Academy of Sciences of the United States).

The main field of the Earth’s magnetic field is generated by flows of liquid iron in the outer core. The Earth’s magnetic field protects us from cosmic radiation particles. Therefore, understanding the processes in the outer core is important to understand the terrestrial shield. Key to this are measurements of the geomagnetic field itself. A second, independent access could be represented by the measurement of minute changes in gravity caused by the fact that the flow in the liquid Earth’s core is associated with mass displacements. The research group has now succeeded to provide the first evidence of such a connection of fluctuations in the Earth’s gravity and magnetic field.

They used magnetic field measurements of the GFZ-satellite CHAMP and extremely accurate measurements of the Earth’s gravity field derived from the GRACE mission, which is also under the auspices of the GFZ. “The main problem was the separation of the individual components of the gravity data from the total signal,” explains Vincent Lesur from the GFZ German Research Centre for Geosciences, who is involved in the study. A satellite only measures the total gravity, which consists of the mass fractions of Earth’s body, water and ice on the ground and in the air. To determine the mass redistribution by flows in the outer core, the thus attained share of the total gravity needs to be filtered out. “Similarly, in order to capture the smaller changes in the outer core, the proportion of the magnetic crust and the proportion of the ionosphere and magnetosphere need to be filtered out from the total magnetic field signal measured by the satellite,” Vincent Lesur explains. The data records of the GFZ-satellite missions CHAMP and GRACE enabled this for the first time.

During the investigation, the team focused on an area between the Atlantic and the Indian Ocean, as the determined currents flows were the highest here. Extremely fast changes (so-called magnetic jerks) were observed in the year 2007 at the Earth’s surface. These are an indication for sudden changes of liquid flows in the upper outer core and are important for understanding the magneto-hydrodynamics in the Earth’s core. Using the satellite data, a clear signal of gravity data from the Earth’s core could be received for the first time.

This results in consequences for the existing conceptual models. Until now, for example, it was assumed that the differences in the density of the molten iron in the earth’s core are not large enough to generate a measurable signal in the earth’s gravitational field. The newly determined mass flows in the upper outer core allow a new approach to Earth’s core hydrodynamics.

Rapid changes in the Earth’s core: The magnetic field and gravity from a satellite perspective

Annual to decadal changes in the earth’s magnetic field in a region that stretches from the Atlantic to the Indian Ocean have a close relationship with variations of gravity in this area. From this it can be concluded that outer core processes are reflected in gravity data. This is the result presented by a German-French group of geophysicists in the latest issue of PNAS (Proceedings of the National Academy of Sciences of the United States).

The main field of the Earth’s magnetic field is generated by flows of liquid iron in the outer core. The Earth’s magnetic field protects us from cosmic radiation particles. Therefore, understanding the processes in the outer core is important to understand the terrestrial shield. Key to this are measurements of the geomagnetic field itself. A second, independent access could be represented by the measurement of minute changes in gravity caused by the fact that the flow in the liquid Earth’s core is associated with mass displacements. The research group has now succeeded to provide the first evidence of such a connection of fluctuations in the Earth’s gravity and magnetic field.

They used magnetic field measurements of the GFZ-satellite CHAMP and extremely accurate measurements of the Earth’s gravity field derived from the GRACE mission, which is also under the auspices of the GFZ. “The main problem was the separation of the individual components of the gravity data from the total signal,” explains Vincent Lesur from the GFZ German Research Centre for Geosciences, who is involved in the study. A satellite only measures the total gravity, which consists of the mass fractions of Earth’s body, water and ice on the ground and in the air. To determine the mass redistribution by flows in the outer core, the thus attained share of the total gravity needs to be filtered out. “Similarly, in order to capture the smaller changes in the outer core, the proportion of the magnetic crust and the proportion of the ionosphere and magnetosphere need to be filtered out from the total magnetic field signal measured by the satellite,” Vincent Lesur explains. The data records of the GFZ-satellite missions CHAMP and GRACE enabled this for the first time.

During the investigation, the team focused on an area between the Atlantic and the Indian Ocean, as the determined currents flows were the highest here. Extremely fast changes (so-called magnetic jerks) were observed in the year 2007 at the Earth’s surface. These are an indication for sudden changes of liquid flows in the upper outer core and are important for understanding the magneto-hydrodynamics in the Earth’s core. Using the satellite data, a clear signal of gravity data from the Earth’s core could be received for the first time.

This results in consequences for the existing conceptual models. Until now, for example, it was assumed that the differences in the density of the molten iron in the earth’s core are not large enough to generate a measurable signal in the earth’s gravitational field. The newly determined mass flows in the upper outer core allow a new approach to Earth’s core hydrodynamics.

A Mississippi river diversion helped build Louisiana wetlands, Penn geologists find

The extensive system of levees along the Mississippi River has done much to prevent devastating floods in riverside communities. But the levees have also contributed to the loss of Louisiana’s wetlands. By holding in floodwaters, they prevent sediment from flowing into the watershed and rebuilding marshes, which are compacting under their own weight and losing ground to sea-level rise.

Reporting in Nature Geoscience, a team of University of Pennsylvania geologists and others used the Mississippi River flood of the spring of 2011 to observe how floodwaters deposited sediment in the Mississippi Delta. Their findings offer insight into how new diversions in the Mississippi River’s levees may help restore Louisiana’s wetlands.

While scientists and engineers have previously proposed ways of altering the levee system to restore some of the natural wetland-building ability of the Mississippi, this is among the only large-scale experiments to demonstrate how these modifications might function.

The study was headed by Douglas Jerolmack, an assistant professor in the Department of Earth and Environmental Science at Penn, and Federico Falcini, who at the time was a postdoctoral researcher in Jerolmack’s lab and is now at the Consiglio Nazionale delle Ricerche in Rome. Benjamin Horton, an associate professor in the Earth and Environmental Science Department; Nicole Khan, a doctoral student in Horton’s lab; and Alessandro Salusti, a visiting undergraduate researcher also contributed to the work. The Penn researchers worked with Rosalia Santoleri, Simone Colella and Gianluca Volpe of the Consiglio Nazionale delle Ricerche; Leonardo Macelloni, Carol B. Lutken and Marco D’Emidio of the University of Mississippi; Karen L. McKee of the U.S. Geological Survey; and Chunyan Li of Louisiana State University.

The 2011 floods broke records across several states, damaged homes and crops and took several lives. The destruction was reduced, however, because the Army Corps of Engineers opened the Morganza Spillway, a river-control structure, for the first time since 1973 to divert water off of the Mississippi into the Atchafalaya River Basin. This action involved the deliberate flooding of more than 12,000 square kilometers and alleviated pressures on downstream levees and spared Baton Rouge and New Orleans from the worst of the flood.

For the Penn researchers, the opening of the Morganza Spillway provided a rare look into how floods along the Mississippi may have occurred before engineered structures were put in place to control the river’s flow.

“While this was catastrophic to the people living in the Atchafalaya Basin, it was also simulating – accidentally – the sort of natural flood that used to happen all the time,” Jerolmack said. “We were interested in how this sort of natural flooding scenario would differ from the controlled floods contained within levees that we normally see in the Delta.”

To capitalize on this opportunity, the team began examining satellite images showing the plume of sediment-laden water emerging from the mouths of the Atchafalaya and Mississippi rivers. They calculated the amount of sediment in the plumes for the duration of the flood based on the ocean color in the satellite images and calibrated these data to field samples taken from a boat in the Gulf of Mexico. Their boat sampling also allowed them to gather data on the speed of the plume and the extent to which river water mixed with ocean water.

From the satellite images, researchers observed that the Mississippi River unleashed a jet of water into the ocean. In contrast, the waters diverted into the Atchafalaya Basin spread out over 100 kilometers of coastline, the sediment lingering in a wide swampy area.

“You have this intentionally flooded Atchafalaya Basin and when those flood waters hit the coast they were trapped there for a month, where tides and waves could bring them back on shore,” Jerolmack said. “Whereas in the Mississippi channel, where all the waters were totally leveed, you could see from satellite images this sort of fire hose of water that pushed the sediment from the river far off shore.”

The researchers used a helicopter to travel to 45 sites across the two basins, where they sampled sediment cores. They observed that sediment deposited to a greater extent in the Atchafalaya Basin than in any area of the Mississippi Basin wetlands, even though the Mississippi River plume contained more total sediment.

The recently deposited sediments lacked plant roots and were different in color and consistency from the older sediments. Laboratory analyses of diatoms, or photosynthetic algae, also revealed another signature of newly deposited sediments: They contained a higher proportion of round diatoms to rod-shaped diatoms than did deeper layers of sediment.

“This diatom ratio can now serve as an indicator for freshwater floods,” Horton said. “With longer sediment cores and analyses of the diatoms, we may be able to work out how many floods have occurred, how much sediment they deposited and what their recurrence intervals were.”

Taken together, the researchers’ findings offer a large-scale demonstration of how flooding over the Atchafalaya’s wide basin built up sediment in wetland areas, compared to the more-focused plume of water from the Mississippi River. Jerolmack says this “natural experiment” provides a convincing and reliable way of gathering data and information about how changes in the Mississippi’s levees and control structures could help restore marsh in other areas of the Delta.

“One of the things that we found here is that the Atchafalaya, which is this wide, slow plume, actually produced a lot of sedimentation over a broad area,” Jerolmack said. “We think that what the Atchafalaya is showing us on a field scale is that this is the sort of diversion that you would need in order to create effective sedimentation and marsh building.”

A Mississippi river diversion helped build Louisiana wetlands, Penn geologists find

The extensive system of levees along the Mississippi River has done much to prevent devastating floods in riverside communities. But the levees have also contributed to the loss of Louisiana’s wetlands. By holding in floodwaters, they prevent sediment from flowing into the watershed and rebuilding marshes, which are compacting under their own weight and losing ground to sea-level rise.

Reporting in Nature Geoscience, a team of University of Pennsylvania geologists and others used the Mississippi River flood of the spring of 2011 to observe how floodwaters deposited sediment in the Mississippi Delta. Their findings offer insight into how new diversions in the Mississippi River’s levees may help restore Louisiana’s wetlands.

While scientists and engineers have previously proposed ways of altering the levee system to restore some of the natural wetland-building ability of the Mississippi, this is among the only large-scale experiments to demonstrate how these modifications might function.

The study was headed by Douglas Jerolmack, an assistant professor in the Department of Earth and Environmental Science at Penn, and Federico Falcini, who at the time was a postdoctoral researcher in Jerolmack’s lab and is now at the Consiglio Nazionale delle Ricerche in Rome. Benjamin Horton, an associate professor in the Earth and Environmental Science Department; Nicole Khan, a doctoral student in Horton’s lab; and Alessandro Salusti, a visiting undergraduate researcher also contributed to the work. The Penn researchers worked with Rosalia Santoleri, Simone Colella and Gianluca Volpe of the Consiglio Nazionale delle Ricerche; Leonardo Macelloni, Carol B. Lutken and Marco D’Emidio of the University of Mississippi; Karen L. McKee of the U.S. Geological Survey; and Chunyan Li of Louisiana State University.

The 2011 floods broke records across several states, damaged homes and crops and took several lives. The destruction was reduced, however, because the Army Corps of Engineers opened the Morganza Spillway, a river-control structure, for the first time since 1973 to divert water off of the Mississippi into the Atchafalaya River Basin. This action involved the deliberate flooding of more than 12,000 square kilometers and alleviated pressures on downstream levees and spared Baton Rouge and New Orleans from the worst of the flood.

For the Penn researchers, the opening of the Morganza Spillway provided a rare look into how floods along the Mississippi may have occurred before engineered structures were put in place to control the river’s flow.

“While this was catastrophic to the people living in the Atchafalaya Basin, it was also simulating – accidentally – the sort of natural flood that used to happen all the time,” Jerolmack said. “We were interested in how this sort of natural flooding scenario would differ from the controlled floods contained within levees that we normally see in the Delta.”

To capitalize on this opportunity, the team began examining satellite images showing the plume of sediment-laden water emerging from the mouths of the Atchafalaya and Mississippi rivers. They calculated the amount of sediment in the plumes for the duration of the flood based on the ocean color in the satellite images and calibrated these data to field samples taken from a boat in the Gulf of Mexico. Their boat sampling also allowed them to gather data on the speed of the plume and the extent to which river water mixed with ocean water.

From the satellite images, researchers observed that the Mississippi River unleashed a jet of water into the ocean. In contrast, the waters diverted into the Atchafalaya Basin spread out over 100 kilometers of coastline, the sediment lingering in a wide swampy area.

“You have this intentionally flooded Atchafalaya Basin and when those flood waters hit the coast they were trapped there for a month, where tides and waves could bring them back on shore,” Jerolmack said. “Whereas in the Mississippi channel, where all the waters were totally leveed, you could see from satellite images this sort of fire hose of water that pushed the sediment from the river far off shore.”

The researchers used a helicopter to travel to 45 sites across the two basins, where they sampled sediment cores. They observed that sediment deposited to a greater extent in the Atchafalaya Basin than in any area of the Mississippi Basin wetlands, even though the Mississippi River plume contained more total sediment.

The recently deposited sediments lacked plant roots and were different in color and consistency from the older sediments. Laboratory analyses of diatoms, or photosynthetic algae, also revealed another signature of newly deposited sediments: They contained a higher proportion of round diatoms to rod-shaped diatoms than did deeper layers of sediment.

“This diatom ratio can now serve as an indicator for freshwater floods,” Horton said. “With longer sediment cores and analyses of the diatoms, we may be able to work out how many floods have occurred, how much sediment they deposited and what their recurrence intervals were.”

Taken together, the researchers’ findings offer a large-scale demonstration of how flooding over the Atchafalaya’s wide basin built up sediment in wetland areas, compared to the more-focused plume of water from the Mississippi River. Jerolmack says this “natural experiment” provides a convincing and reliable way of gathering data and information about how changes in the Mississippi’s levees and control structures could help restore marsh in other areas of the Delta.

“One of the things that we found here is that the Atchafalaya, which is this wide, slow plume, actually produced a lot of sedimentation over a broad area,” Jerolmack said. “We think that what the Atchafalaya is showing us on a field scale is that this is the sort of diversion that you would need in order to create effective sedimentation and marsh building.”

Improving effectiveness of solar geoengineering

Solar radiation management is a type of geoengineering that would manipulate the climate in order to reduce the impact of global warming caused by greenhouse gasses. Ideas include increasing the amount of aerosols in the stratosphere, which could scatter incoming solar light away from Earth’s surface, or creating low-altitude marine clouds to reflect these same rays.

Research models have indicated that the climatic effect of this type of geoengineering will vary by region, because the climate systems respond differently to the reflecting substances than they do to the atmospheric carbon dioxide that traps warmth in Earth’s atmosphere. New work from a team including Carnegie’s Ken Caldeira uses a climate model to look at maximizing the effectiveness of solar radiation management techniques. Their work is published October 21st by Nature Climate Change.

Attempting to counteract the warming effect of greenhouse gases with a uniform layer of aerosols in the stratosphere, would cool the tropics much more than it affects polar areas. Greenhouse gases tend to suppress precipitation and an offsetting reduction in amount of sunlight absorbed by Earth would not restore this precipitation. Both greenhouse gases and aerosols affect the distribution of heat and rain on this planet, but they change temperature and precipitation in different ways in different places. Varying the amount of sunlight deflected away from the Earth both regionally and seasonally could combat some of this problem.

By tailoring geoengineering efforts by region and by need, the team-led by California Institute of Technology’s Douglas MacMartin-was able to explore ways to maximize effectiveness while minimizing the side effects and risks of this type of planetary intervention.

“These results indicate that varying geoengineering efforts by region and over different periods of time could potentially improve the effectiveness of solar geoengineering and reduce climate impacts in at-risk areas,” Caldeira said. “For example, these approaches may be able to reverse long-term changes in the Arctic sea ice.”

The study used a sophisticated climate model, but the team’s model is still much simpler than the real world. Interference in Earth’s climate system, whether intentional or unintentional, is likely to produce unanticipated outcomes.

“We have to expect the unexpected,” Caldeira added. “The safest way to reduce climate risk is to reduce greenhouse gas emissions.”

Improving effectiveness of solar geoengineering

Solar radiation management is a type of geoengineering that would manipulate the climate in order to reduce the impact of global warming caused by greenhouse gasses. Ideas include increasing the amount of aerosols in the stratosphere, which could scatter incoming solar light away from Earth’s surface, or creating low-altitude marine clouds to reflect these same rays.

Research models have indicated that the climatic effect of this type of geoengineering will vary by region, because the climate systems respond differently to the reflecting substances than they do to the atmospheric carbon dioxide that traps warmth in Earth’s atmosphere. New work from a team including Carnegie’s Ken Caldeira uses a climate model to look at maximizing the effectiveness of solar radiation management techniques. Their work is published October 21st by Nature Climate Change.

Attempting to counteract the warming effect of greenhouse gases with a uniform layer of aerosols in the stratosphere, would cool the tropics much more than it affects polar areas. Greenhouse gases tend to suppress precipitation and an offsetting reduction in amount of sunlight absorbed by Earth would not restore this precipitation. Both greenhouse gases and aerosols affect the distribution of heat and rain on this planet, but they change temperature and precipitation in different ways in different places. Varying the amount of sunlight deflected away from the Earth both regionally and seasonally could combat some of this problem.

By tailoring geoengineering efforts by region and by need, the team-led by California Institute of Technology’s Douglas MacMartin-was able to explore ways to maximize effectiveness while minimizing the side effects and risks of this type of planetary intervention.

“These results indicate that varying geoengineering efforts by region and over different periods of time could potentially improve the effectiveness of solar geoengineering and reduce climate impacts in at-risk areas,” Caldeira said. “For example, these approaches may be able to reverse long-term changes in the Arctic sea ice.”

The study used a sophisticated climate model, but the team’s model is still much simpler than the real world. Interference in Earth’s climate system, whether intentional or unintentional, is likely to produce unanticipated outcomes.

“We have to expect the unexpected,” Caldeira added. “The safest way to reduce climate risk is to reduce greenhouse gas emissions.”