December 2020 – Geobites

December 30, 2020December 30, 2020

Antarctic krill and their role in ocean carbon cycling

Antarctic Krill under a microscope. Photo courtesy of Uwe Kils, CC-BY-SA 3.0

Paper: Manno et al. (2020)

The transfer of carbon from the surface ocean to the deep ocean, or carbon export, can strongly influence climate. The main pathway of carbon export in the ocean is through sinking particles, also known as the biological carbon pump. These sinking particles can include plankton biomass, aggregates of cells, and zooplankton feces and molts. Understanding what contributes to carbon export is important in understanding how this may change as temperatures warm due to climate change.

A recent study by Manno et al. found that Antarctic krill in the Southern Ocean may play a significant role in transporting carbon to the deep ocean through their carcasses, fecal material, and most notably their molts, or shedding of their shells. Exoskeletons are not only an important vehicle for carbon export but also provide food to animals living on the seafloor. This is the first study to investigate the contribution of krill molts to carbon export in the Southern Ocean.

December 29, 2020December 29, 2020

When Lightning Strikes! Fulgurite Formation and Earth’s Weather

Paper: Lightning-induced weathering of Cascadian volcanic peaks

Authors: Jonathan M. Castro, Franziska Keller, Yves Feisel, Pierre Lanari, Christoph Helo, Sebastian P. Mueller, C. Ian Schipper, Chad Thomas

The bright flashes followed by the loud thunderclaps of large storms are inherently transient, but a recent study by Castro et al proposes a new approach to investigating the history of storm activity and extreme weather events on Earth: through fossilized lightning strikes, or fulgurites.

December 23, 2020December 23, 2020

How did valleys form on early Mars? Some say in ice…

Featured image: The Nirgal Vallis river valley on Mars as seen by the HRSC Camera onboard the European Space Agency’s Mars Express mission. Image credit: ESA/DLR/FU Berlin.

Paper: Valley formation on early Mars by subglacial and fluvial erosion.

Authors: Anna Grau Galofre, A. Mark Jellinek & Gordon R. Osinski.

“Some say the world will end in fire/ Some say in ice” begins the famous poem by Robert Frost. But what about how worlds begin? For years the theory of a “warm and wet” early Mars has been the conventional explanation for the vast valley networks formed billions of years ago that we can see on the surface today. Now, a new study suggests that at least some of these valleys could have formed under colossal ice sheets, in a distinctly more icy world.

December 22, 2020December 31, 2020

Looking below ground for secrets to drought resilience

Featured image: Oak savanna near the Santa Ynez mountains in California. Clyde Frogg, public domain.

Paper: Low Subsurface Water Storage Capacity Relative to Annual Rainfall Decouples Mediterranean Plant Productivity and Water Use From Rainfall Variability

Authors: Hahm, W. J., Dralle, D. N., Rempe, D. M., Bryk, A. B., Thompson, S. E., Dawson, T. E., & Dietrich, W. E.

Between 2011 and 2016, a severe drought killed over 100 million trees in California. However, not all places responded to this drought in the same way. In some locations, trees and other plants seemed hardly affected, while in other places mortality was widespread. What caused this difference? In a 2019 study, Hahm and colleagues explored the role that water storage in ecosystems has on their resilience to drought. With extreme droughts becoming more common due to climate change, understanding why certain areas are more vulnerable is important for making predictions and improving forest management.

December 15, 2020December 14, 2020

Satellite Technology Helps Discover New Weather Phenomena: Lightning Megaflashes

Featured Image from Bethany Laird on Unsplash

Paper: Where are the Most Extraordinary Lightning Megaflashes in the Americas?

Author: Michael Peterson

Most lightning flashes only last 0.2 seconds, meaning if you blink at the wrong moment, you could miss it. However, scientists have developed new lightning-detection instruments, known as Geostationary Lightning Mappers (GLMs), that never miss a flash. The GLMs are aboard the two Geostationary Operational Environmental Satellites (GOES-West and GOES-East), which are in stationary orbits over the Earth’s western hemisphere. With the data from the GLMs, atmospheric scientists have discovered new lightning phenomena called “megaflashes” which can light up the sky for as long as 16 seconds.

December 9, 2020December 8, 2020

Building mountains

Featured image: Yushan (Jade Mountain) in Taiwan. From Wikimedia Commons by Kailing3 under a CC-BY-SA 3.0 license.

Paper: Coseismic Uplift of the 1999 M_w7.6 Chi‐Chi Earthquake and Implication to Topographic Change in Frontal Mountain Belts

Authors: R.Y. Chuang, C.H. Lu, C.J. Yang, Y.S. Lin, and T.Y. Lee

Journal: Geophysical Research Letters

The height of a mountain range results from a hard-fought battle between tectonic plates and the forces of erosion. Earthquakes generated by clashes between plates cause the upward motion of rock even as they shake the landscape, causing large and numerous landslides. When a large earthquake occurs, which process wins? Does more rock go up than come down, leading to a higher mountain range? Or does shaking-induced erosion remove more material than is uplifted by the earthquake? New research suggests that earthquakes might be able to build mountains up faster than landslides can bring them down.

December 8, 2020December 9, 2020

The role of carbon in a changing Arctic

Paper: Freshening of the western Arctic negates anthropogenic carbon uptake potential

Authors: R.J. Woosley and F.J. Millero

Journal: Limnology and Oceanography

As human generated emissions of carbon dioxide continue to increase, scientists seek to understand the potential for ‘sinks’, or places that the excess CO₂ can move in the global carbon cycle, to take up and store some of the increased emissions. Understanding how these carbon sinks may react to increasing global emissions helps to better predict both the rate of atmospheric increase in the future and the potential response of global ecosystems, including major sinks in forests and oceans.

December 3, 2020December 8, 2020

Deep Sea Bacteria have Thrived for Millions of Years

Featured Image courtesy Yannis Papanastasopoulos, Unsplash.

Paper: Atribacteria reproducing over millions of years in the Atlantic abyssal subseafloor

Authors: Aurèle Vuillemin, Sergio Vargas, Ömer K. Coskun, Robert Pockalny, Richard W. Murray, David C. Smith, Steven D’Hondt, William D. Orsi

If you, like me, imagine the seafloor to be inhabited by strange, mysterious creatures like vampire squids and goblin sharks, think again: bacteria continue to surprise us with their resilience in the oddest of environments. Scientists have detected microbes living in the mud and rocks on the seafloor, but we don’t know much about them. Are they alive? How do they get energy in such a nutrient-poor environment? Given the inhospitable conditions in the sub-seafloor, scientists have thought that most of these microbes were close to the energy limit for life, which is an estimate of the minimum amount of energy required to sustain life as we know it. For this reason, we’ve assumed that subseafloor microbes die faster than they grow because there simply isn’t enough energy in the deep sea to sustain life long-term.

December 1, 2020January 21, 2021

The strange case of the Kansas earthquake

Featured image: Karst rocks in Segovia, Spain. Photo by Luis Fernández García, CC-BY-SA 2.1.

Paper: Injection-induced earthquakes near Milan, Kansas controlled by karstic networks
Authors: Charlène Joubert, Reza Sohrabi, Justin L. Rubinstein, Gunnar Jansen, Stephen A. Miller

On November 12^th, 2014, a magnitude 4.9 earthquake rattled the city of Milan, Kansas. This event was the largest earthquake ever recorded in Kansas, adding to a trend of increasing seismic activity in the state since 2012. What could cause this kind of tectonic excitement in the stable central US?