Highlights Collection

A compilation of AGU journal content that has been featured as Research Spotlights, Press Releases, Editors’ Highlights, Editors’ Vox, and GeoSpace blog posts (most recent listed first)

AGU Blog Post, 13 November 2017 in GRL

Scientists may have solved mystery of rapidly rising Indian Ocean sea level

Sea levels around the world have risen by 1.7 millimeters (0.07 inches) on average each year since 1880, but in recent years, scientists have observed a rapid increase in sea level in the north Indian Ocean. Tide gauge records and other datasets reveal the pace of sea level rise in the north Indian Ocean has accelerated to 3.1 millimeters (0.12 inches) per year within the last three decades.

The accelerating sea level rise has confounded scientists but new research claims weakening of South Asian monsoons may be to blame.

A new study in Geophysical Research Letters, a journal of the American Geophysical Union, uses climate and sea level data from the past several decades to connect the Indian Ocean’s sea level rise to its changing monsoon circulation…More

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AGU Blog Post, 13 November 2017 in Earth's Future

Study: Major return on investment from improving climate observations

A well-designed climate observing system could help scientists answer knotty questions about climate while delivering trillions of dollars in benefits by providing decision makers information they need to protect public health and the economy in the coming decades, according to a new study published today.

The flip side is also true, said Elizabeth Weatherhead, a scientist at the Cooperative Institute for Research in Environmental Studies (CIRES) at the University of Colorado Boulder in Boulder, Colorado and lead author of the new study. The cost of failing to invest in improving our ability to predict and plan for droughts, floods, extreme heat events, famine, sea level rise and changes in freshwater availability could reach hundreds of billions of dollars each year, according to the new study accepted for publication in Earth’s Future, a journal of the American Geophysical Union.

“Improving our understanding of climate not only offers large societal benefits but also significant economic returns,” Weatherhead said. “We’re not specifying which measurement or observing systems to target, we’re simply saying it’s a smart investment to address the most pressing societal needs.”…More

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AGU Blog Post, 13 November 2017 in Earth's Future

Rising sea levels could weaken coral reefs’ protective influence on Brazil’s coast

Rising sea levels could diminish the ability of Brazil’s coral reef systems to weaken incoming ocean waves, resulting in stronger waves hitting populated areas on the Brazilian coastline, according to new research published in Earth’s Future, a journal of the American Geophysical Union.

The new study examined the effects of sea level rise on the energy of waves reaching the coastline of northeast Brazil, home to many famous beaches and the largest coral reef system in the South Atlantic. These reefs buffer waves hitting the coast and protect the shore from erosion. The study’s authors found higher sea levels means waves hitting the coastline will pass further above the coral reefs than they do now, reducing the reefs’ protective influence.

As a result, these waves will reach the coast with up to a 90 percent increase in power and will accelerate erosion of the coastline, according to the new study. The new results support previous studies that have found sea level rise will boost wave power, negatively impacting coral reef ecosystems and populated coastal areas…More

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Press Release, 13 November 2017 in Earth's Future

Human-caused warming increasing likelihood of record-breaking hot years

A new study finds human-caused global warming is significantly increasing the rate at which hot temperature records are being broken around the world.

Global annual temperature records show there were 17 record hot years from 1861 to 2005. The new study examines whether these temperature records are being broken more often and if so, whether human-caused global warming is to blame.

The results show human influence has greatly increased the likelihood of record-breaking hot years occurring on a global scale. Without human-caused climate change, there should only have been an average of seven record hot years from 1861 to 2005, not 17. Further, human-caused climate change at least doubled the odds of having a record-breaking hot year from 1926 to 1945 and from 1967 onwards, according to the new study…More

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AGU Blog Post, 7 November 2017 in JGR: Oceans

Polluted groundwater eroding Hawaiian coral reefs, study shows

Local land-based pollution makes coral reefs more vulnerable to ocean acidification and could trigger coastal coral reef ecosystem collapses sooner than projected, according to new research.

Coral reefs are threatened globally by ocean acidification caused by rising levels of atmospheric carbon dioxide. The carbon dioxide influx heightens the ocean’s acidity, creating an environment that stunts coral growth.

The new study, accepted for publication in the Journal of Geophysical Research: Oceans, a journal of the American Geophysical Union, finds local land-based pollution can make coral reefs even more vulnerable to ocean acidification by magnifying its effects.

The new study finds pollution from a wastewater treatment facility in west Maui, Hawaii, has drastically weakened local coral reefs for more than 10 years. By increasing local seawater acidity and nutrient levels, the polluted water has instigated harmful bioerosion and inhibited coral reef growth…More

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Editors' Highlight, 7 November 2017 in JGR: Oceans

Is global warming suppressing canonical El Niño?

Li et al. [2017] shed new light on the interwoven relationship between the diversity of El Niño events and the trending background state of the tropical Pacific. The authors use instrumental observations since the late nineteenth century to reveal a gradual cooling trend in the surface temperatures of the eastern equatorial Pacific Ocean. This trend is not a perfectly straight line—it tracks the undulations amid the general upward trend of global mean surface temperature very well. Whether an El Niño is centered in the central or eastern Pacific (a major aspect of ENSO diversity) is shown to be influenced by this slowly evolving background coolness of the eastern equatorial Pacific. The center of air-sea interaction is shifting westward away from the cooling waters, which suppresses the large-scale coupled feedback named after Jacob Bjerknes, resulting in more El Niño events peaking in the central Pacific.

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Editors' Highlight, 7 November 2017 in JGR: Oceans

Quantifying the air-sea fluxes of oxygen

Bushinsky et al. have created, for the first time, an internally consistent oxygen dataset that permits them to address net air-sea O2 fluxes. Based on data from ARGO-style floats, they present new and existing observations of air-sea oxygen fluxes over the Southern Ocean. This paper represents a milestone contribution in our ability to quantify the air-sea fluxes of oxygen.

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Editors' Highlight, 7 November 2017 in JGR: Solid Earth

How to understand the inner plumbing of volcanoes

We have become increasingly good at measuring external volcano shape thanks to the development of satellite technology. However, it remains a challenge to understand the subsurface structure and systems. This paper presents a model to link the external geometry of volcanos with their inner structure. Although many volcanoes have more complex formation histories than those modeled, the authors use the idealized approach to develop analytical solutions which make the relationships easier to see. This approach has the potential to provide a wide range of information on the plumbing system of volcanoes, including the potential hazard associated with volcanoes for which we have essentially no information. Overall, this paper is a useful addition to earlier models of volcano evolution.

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Press Release, 7 November 2017 in GRL

More Greenland glaciers threatened by climate change than previously thought

New maps of Greenland’s coastal seafloor and bedrock beneath its massive ice sheet show that two to four times as many coastal glaciers are at risk of accelerated melting due to climate change as previously thought.

In a new study, researchers at the University of California at Irvine (UCI), NASA and 30 other institutions have published the most comprehensive, accurate and high-resolution relief maps ever made of Greenland’s bedrock and coastal seafloor. The new study was published today in Geophysical Research Letters, a journal of the American Geophysical Union.

The top 200 meters (600 feet) of ocean water around Greenland comes from the Arctic and is relatively cold. But the water below 200 meters comes from farther south and is 3 to 4 degrees Celsius (6 to 8 degrees Fahrenheit) warmer than the water above…More

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Press Release, 7 November 2017 in GRL

Dinosaur-killing asteroid impact may have cooled Earth’s climate more than previously thought

The Chicxulub asteroid impact that wiped out the dinosaurs likely released far more climate-altering sulfur gas into the atmosphere than originally thought, according to new research.

A new study makes a more refined estimate of how much sulfur and carbon dioxide gas were ejected into Earth’s atmosphere from vaporized rocks immediately after the Chicxulub event. The study’s authors estimate more than three times as much sulfur may have entered the air compared to what previous models assumed, implying the ensuing period of cool weather may have been colder than previously thought.

The new study lends support to the hypothesis that the impact played a significant role in the Cretaceous-Paleogene extinction event that eradicated nearly three-quarters of Earth’s plant and animal species…More

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Editors' Highlight, 7 November 2017 in GRL

Triggers for the spring phytoplankton bloom

Within ocean sciences, there is currently considerable interest in mesoscale eddies and their impacts on biology. This paper makes a contribution to this scientific field by examining how mesoscale eddies affect the timing of the spring bloom of phytoplankton in the Japan Sea. By contrasting bloom events in cyclonic and anti-cyclonic eddies, the authors determine important processes needed for initiating blooms. The mechanisms are general and may apply to other regions of the world ocean.

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Editors' Highlight, 7 November 2017 in JGR: Atmospheres

Contribution of natural geologic seepage to methane emissions

The process of natural geologic seepage has received little attention from the atmospheric science community despite its potential contribution to climate change. This paper considers one particular methane seep, the La Brea tar pits, located within a city park in Los Angeles. The authors found that the emissions of methane from this area were the largest yet measured from a naturally occurring geologic seep in the United States. They data reveal large methane and alkane seepage into the atmosphere, with gases escaping from the asphalt, soil and lakes in the park.

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Editors' Highlight, 7 November 2017 in JGR: Atmospheres

Higher accuracy global ozone data

This paper presents the results of a major, international effort to homogenize and reprocess ozonesonde data for consistency. This large data set is used by many satellite and modeling groups. The results in this paper demonstrate the value of the reprocessing, and for those who’ve used this data in prior studies, they should be alerted to the improved quality of the new version of the data. This revision of the data now puts the data accuracy at 5 percent, the target for satellite validation, and the “gold standard” for ozone measurement.

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AGU Blog Post, 7 November 2017 in JGR: Atmospheres

New approach to geoengineering simulations is significant step forward

Using a sophisticated computer model, scientists have demonstrated for the first time that a new research approach to geoengineering could potentially be used to limit Earth’s warming to a specific target while reducing some of the risks and concerns identified in past studies, including uneven cooling of the globe.

The scientists developed a specialized algorithm for an Earth system model that varies the amount and location of geoengineering — in this case, injections of sulfur dioxide high into the atmosphere — that would in theory be needed, year to year, to effectively cap warming. They caution, however, that more research is needed to determine if this approach would be practical, or even possible, in the real world…The research findings are detailed in a series of papers published today in a special issue of the Journal of Geophysical Research – Atmospheres…More

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Editors' Highlight, 30 October 2017 in Space Weather

Comparing the accuracy of geomagnetic field models

Improving models of the geomagnetic field is important to radiation belt studies, determining when satellites are on the same magnetic field line, and mapping from the ionosphere to the magnetotail or vice versa, to name just a few applications. Brito and Morley [2017] present a method for comparing the accuracy of several versions of the Tsyganenko empirical magnetic field models and for optimizing the empirical magnetic field model using in situ magnetic field measurements. The study was carried out for intervals of varied geomagnetic activity selected by the Geospace Environment Modeling Challenge for the Quantitative Assessment of Radiation Belt Modeling Focus Group. The authors describe a method for improving the results of various Tsyganenko magnetic field models, especially with respect to outliers, using a new cost function, various metrics and Nelder-Mead optimization. Importantly this model evaluation was based on points in the magnetosphere that were not used for fitting. Thus, the results provide an independent validation of the method. The model, known as TS04, produced the best results after optimization, generating a smaller error in 57.3% of the points in the tested data set when compared to the standard (unoptimized) inputs. The results of this study include a set of optimized parameters that can be used to evaluate the models studied in this paper. These optimized parameters are included as supplementary material so that the broader scientific community can use the optimized magnetic field models immediately, and without any additional code development, using any standard implementation of the magnetic field models tested in the study.

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Press Release, 30 October 2017 in JGR: Planets

Dawn finds possible ancient ocean remnants at Ceres

Minerals containing water are widespread on Ceres, suggesting the dwarf planet may have had a global ocean in the past. What became of that ocean? Could Ceres still have liquid today? Two new studies from NASA’s Dawn mission shed light on these questions.

In one study, the Dawn team found Ceres’ crust is a mixture of ice, salts and hydrated materials that were subjected to past and possibly recent geologic activity, and this crust represents most of that ancient ocean. The second study builds off the first and suggests there is a softer, easily deformable layer beneath Ceres’ rigid surface crust, which could be the signature of residual liquid left over from the ocean, too.

“More and more, we are learning that Ceres is a complex, dynamic world that may have hosted a lot of liquid water in the past, and may still have some underground,” …More

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Editors' Highlight, 30 October 2017 in JGR: Space Physics

Analyzing a 3-D kinetic simulation of a vortex-induced reconnection event

This paper presents an analysis of a 3D fully-kinetic simulation of Kelvin-Helmholz vortices along Earth’s magnetopause. The results of the simulation are compared to observations from NASA’s Magnetospheric Multiscale (MMS) mission. The authors present evidence of secondary, turbulent reconnection, a preference for reconnection on one side of the mixing layer between the two plasmas, and formation of a new mixing layer with strong electron parallel heating. This work shows how magnetic reconnection allows collisionless plasmas to behave globally in ways very similar to collisional fluids, but with unique magnetic signatures. It should be of significant interest to the magnetospheric and plasma physics communities.

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Editors' Highlight, 30 October 2017 in GRL

Explaining the early lunar dynamo

The magnetic signatures of lunar samples suggest that a long-lived dynamo could have existed in the ancient Moon. This paper uses energy budgets to assess whether this may have been the case. The authors found that the Moon is not nearly energetic enough for such a dynamo, which requires exotic mechanisms to explain the observations. This research addresses an important open question about the Moon’s magnetic field.

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Editors' Highlight, 30 October 2017 in GRL

Continuing the debate on causes of Arctic winter warming

There has been longstanding debate about the causes of Arctic warming but this paper makes a significant step towards clarifying and resolving some of the confusion. It revisits the earlier work of Screen and Simmonds (2010) and comes to very different conclusions regarding the mechanisms behind surface warming during the fall and winter seasons. The paper is particularly interesting in that the authors of that previous paper are also among the authors of this paper. It is refreshingly positive to see researchers with different viewpoints come together to hash out their differences and work towards a consensus, enabling the community as a whole to make progress.

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AGU Blog Post, 30 October 2017 in GRL

Scientists use seismic waves to measure tornado intensity

Seismic waves generated by tornadoes when they touch down could be used to measure a twister’s intensity, according to a new study.

The new research examined a catastrophic tornado that struck Joplin, Missouri in May 2011 and revealed the size of seismic waves produced by the tornado on the ground correlated with its strength.

The results suggest researchers can estimate a large tornado’s strength by measuring the seismic waves it creates, a finding that could open the door to devising more accurate methods to study tornadoes from the ground, according to the authors of the new study published in Geophysical Research Letters, a journal of the American Geophysical Union.

Weather authorities currently forecast the locations of tornadoes using surface weather stations and Doppler radar. But they still rely on storm chasers and spotters to find out when a tornado touches down. There is also no way to directly measure a tornado’s wind speed, so authorities rely on damage reports to indirectly judge its intensity.

“Our results have applications for developing a more quantitative measure of a tornado’s strength,” said Anne Valovcin, a graduate student in the Earth science department at the University of California in Santa Barbara and lead author of the new study…More

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