. Scientific Frontline: Earth Science
Showing posts with label Earth Science. Show all posts
Showing posts with label Earth Science. Show all posts

Sunday, January 22, 2023

Traded species have distinctive life histories with extended reproductive lifecycles

Invasive species can cause huge environmental problems and monetary costs
Photo Credit: Pierre Bamin

A new study by researchers from Durham University, UK, Queen’s University Belfast, UK, University of Extremadura, Spain and Swansea University, UK have revealed that vertebrate species involved in the live wildlife trade have distinctive life history traits, biological characteristics that determine the frequency and timing of reproduction.

Researchers discovered that traded species produce large numbers of offspring across long reproductive lifespans, an unusual profile that is likely financially advantageous for trades involving captive breeding such as the pet, food and fur/skin trades.

Traded species that have also been introduced into non-native areas have a more extreme version of this same life history profile, suggesting that species most likely to become problematic invaders are at a heightened risk of trade and release.

The study suggests that humans favor species with high reproductive output for trade and release, which are the very species likely to become problematic invaders in future.

Researchers point out that life history traits are therefore potentially useful for predicting future invasions.

Friday, January 20, 2023

Unprecedented Levels of High-Severity Fire Burn in Sierra Nevada Forests

A firefighter helps containment efforts during the Creek Fire response in 2020.
Photo Credit: USDA, Pacific Southwest Forest Service

High-severity wildfire is increasing in Sierra Nevada and Southern Cascade forests and has been burning at unprecedented rates compared to the years before Euro-American settlement, according to a study from the Safford Lab at the University of California, Davis, and its collaborators. Those rates have especially shot up over the past decade. 

For the study, published in the journal Ecosphere, scientists analyzed fire severity data from the U.S. Forest Service and Google Earth Engine, across seven major forest types. 

They found that in low- and middle-elevation forest types, the average annual area that burned at low-to-moderate severity has decreased from more than 90% before 1850 to 60-70% today. 

At the same time, the area burned annually at high severity has nearly quintupled, rising from less than 10% to 43% today. (High-severity burns are those where more than 95% of aboveground tree biomass is killed by fire.)

Malformed seashells, ancient sediment provide clues about Earth’s past

A drone photo of the JOIDES Resolution in the Mentelle Basin, where Northwestern scientists drilled for ancient sediment.
Photo Credit: Gabriele Tagliaro, University Sao Paulo

Nearly 100 million years ago, the Earth experienced an extreme environmental disruption that choked oxygen from the oceans and led to elevated marine extinction levels that affected the entire globe. 

Now, in a pair of complementary new studies, two Northwestern University-led teams of geoscientists report new findings on the chronology and character of events that led to this occurrence, known as Ocean Anoxic Event 2 (OAE2), which was co-discovered more than 40 years ago by late Northwestern professor Seymour Schlanger. 

By studying preserved planktonic microfossils and bulk sediment extracted from three sites around the world, the team collected direct evidence indicating that ocean acidification occurred during the earliest stages of the event, due to carbon dioxide (CO2) emissions from the eruption of massive volcanic complexes on the sea floor.

In one of the new studies, the researchers also propose a new hypothesis to explain why ocean acidification led to a strange blip of cooler temperatures (dubbed the “Plenus Cold Event”), which briefly interrupted the otherwise intensely hot greenhouse period.

Thursday, January 19, 2023

Knowledge is Flowing: Connecting the Dots and Chipping Away at Modeling Uncertainty

UConn researchers are working to improve the modeling for understanding how water moves through the ecosystem
Photo Credit: SFLORG stock image

When working to find solutions for complex problems, it can be easy to focus either too broadly or too narrowly. Oftentimes the answers lie somewhere in the middle.

UConn Department of Natural Resources and the Environment researcher James Knighton and his group are working to connect two fields of research – one with a global focus, the other with a local focus — to overcome a disconnect and improve models used for studying how water moves through the earth’s systems. The study is published in the Journal of Advances in Modeling Earth Systems.

Knighton explains that projections for climate change over the next 50 to 100 years rely on complex models called general circulation models or earth systems models.

“In those models, people try to simulate the flow of the atmosphere, the flow of the ocean, water exchanges with the continents, how that water moves as freshwater out to the ocean, and how a significant portion of it moves back to the atmosphere. About half of all rain that falls on land goes back to the atmosphere directly and most of that through plants.”

Researchers uncover secrets on how Alaska’s Denali Fault formed

Denali fault trace cutting through Gakona Glacier, just after the 2002 earthquake. Tracks are from where geologists measured the fault offset.
Photo Credit: Peter Haeussler/U.S. Geological Survey. Licensed under Public Domain.

A study by Brown researchers finds that changes in tectonic plate thickness across the Denali Fault in Alaska impacts where it is located, shedding light on how major faults and earthquakes occur.

When the rigid plates that make up the Earth’s lithosphere brush against one another, they often form visible boundaries, known as faults, on the planet’s surface. Strike-slip faults, such as the San Andreas Fault in California or the Denali Fault in Alaska, are among the most well-known and capable of seriously powerful seismic activity.

Studying these faults can help geoscientists not only better understand the process of plate tectonics, which helped form the planet’s continents and mountains, but also better model their earthquake hazards. The problem is that most studies on these types of faults are (quite literally) shallow, looking only at the upper layer of the Earth’s crust where the faults form.

New research led by Brown University seismologists digs deeper into the Earth, analyzing how the part of the fault that’s near the surface connects to the base of the tectonic plate in the mantle. The scientists found that changes in how thick the plate is and how strong it is deep into the Earth play a key role in the location of Alaska’s Denali Fault, one of the world’s major strike-slip faults.

Tuesday, January 17, 2023

Increased atmospheric dust is masking greenhouse gases’ warming effect

A visualization from space of the “Godzilla” dust storm on June 18, 2020, when desert dust traveled from the Sahara to North America. A UCLA study finds that an increase in microscopic dust in the atmosphere has concealed the full extent of greenhouse gases’ potential for warming the planet.
Image Credit: NASA Scientific Visualization Studio  

A new study shows that global atmospheric dust — microscopic airborne particles from desert dust storms — has a slight overall cooling effect on the planet that has hidden the full amount of warming caused by greenhouse gases.

The UCLA research, published today in Nature Reviews Earth and Environment, found that the amount of desert dust has grown roughly 55% since the mid-1800s, which increased the dust’s cooling effect.

This study is the first to demonstrate the overall cooling effect of atmospheric desert dust. Some effects of atmospheric dust warm the planet, but because other effects of dust actually counteract warming — for example by scattering sunlight back into space and dissipating high clouds that warm the planet — the study calculated that dust’s overall effect is a cooling one.

Should dust levels decline — or even simply stop growing — warming could ramp up, said UCLA atmospheric physicist Jasper Kok, the study’s lead author.

Climate Change Likely to Uproot More Amazon Trees

Members of NGEE-Tropics visit what they named “Blowdown Gardens,” an area that experienced windthrow near one of their field sites in the Amazon. Researchers have found a relationship between atmospheric conditions and large areas of tree death.
Photo Credit: Charlie Koven/Berkeley Lab

Tropical forests are crucial for sucking up carbon dioxide from the atmosphere. But they’re also subject to intense storms that can cause “windthrow” – the uprooting or breaking of trees. These downed trees decompose, potentially turning a forest from a carbon sink into a carbon source.

A new study finds that more extreme thunderstorms from climate change will likely cause a greater number of large windthrow events in the Amazon rainforest. This is one of the few ways that researchers have developed a link between storm conditions in the atmosphere and forest mortality on land, helping fill a major gap in models.

“Building this link between atmospheric dynamics and damage at the surface is very important across the board,” said Jeff Chambers, a senior faculty scientist at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), and director of the Next Generation Ecosystem Experiments (NGEE)-Tropics project, which performed the research. “It’s not just for the tropics. It’s high-latitude, low-latitude, temperate-latitude, here in the U.S.”

Monday, January 16, 2023

Deflecting lightning with a laser lightning rod

During tests carried out on the summit of the Säntis by Jean-Pierre Wolf and Aurélien Houard's team, the scientists noted that the discharge could follow the laser beam of the "LLR" for several dozen meters before reaching the tower of the operator Swisscom (in red and white).
Photo Credit: Xavier Ravinet - UNIGE

A European consortium led by UNIGE, École Polytechnique (Paris), EPFL, hes-so and TRUMPF has managed to guide lightning using a high-power laser installed at the top of Mount Säntis in Switzerland.

Forest fires, power cuts and damaged infrastructure…lightning fascinates and destroys in equal measure, causing as many as 24,000 deaths a year worldwide not to mention widespread destruction. Even today, the lightning rod invented by Benjamin Franklin is the best form of protection. And yet, these rods do not always provide optimal protection for sensitive sites. A European consortium consisting of the University of Geneva (UNIGE), École Polytechnique (Paris), EPFL, hes-so and TRUMPF scientific lasers (Munich) has developed a promising alternative: the Laser Lightning Rod or LLR. After testing the LLR on the summit of Säntis (in Switzerland), the researchers now have proof of its feasibility. The rod can deflect lightning over several dozen meters even in poor weather. The results of this research are published in the journal Nature Photonics.

Friday, January 6, 2023

The Pacific Ocean’s oxygen-starved ‘OMZ’ is growing, new Princeton research finds

The Pacific Oxygen Minimum Zone in 3D Researchers created this visualization of the Pacific’s oxygen minimum zone from observations and the 2018 World Ocean Atlas. The colors approximately indicate the core (purple) that has almost no oxygen and is contracting, the low-oxygen outer layer (orange) that is expanding, and a transitional zone in between (pink).  
Animation Credit: by Julius Busecke in collaboration with Bane Sullivan

Areas of low-oxygen water stretch for thousands of miles through the world’s oceans. The largest of these “oxygen minimum zones” (OMZs) is found along the Pacific coast of North and South America, centered off the coast of Mexico.

Until recently, climate models have been unable to say whether OMZs will grow or shrink from climate change, in part because OMZs result from two opposing processes: oxygen supplied by ocean circulation and oxygen used by sea life.

Now, a team led by Princeton’s Laure Resplandy has confidently predicted that the boundaries of the Pacific OMZ, the planet’s largest, will expand by as much as 2 million additional cubic miles (8 million cubic kilometers) — both upward toward the sea surface and outward toward the coast — by the end of the century.

How evolution works

Examples of phenotypic innovations across the eukaryotic tree of life, to which newly developed approaches can be applied.
Graphic Credit: Kenji Fukushima

What genetic changes are responsible for the evolution of phenotypic traits? This question is not always easy to answer. A newly developed method now makes the search much easier.

With its powerful digging shovels, the European mole can burrow through the soil with ease. The same applies to the Australian marsupial mole. Although the two animal species live far apart, they have developed similar organs in the course of evolution - in their case, extremities ideally adapted for digging in the soil.

Science speaks of "convergent evolution" in such cases, when animal, but also plant species independently develop features that have the same shape and function. There are many examples of this: Fish, for example, have fins, as do whales, although they are mammals. Birds and bats have wings, and when it comes to using poisonous substances to defend themselves against attackers, many creatures, from jellyfish to scorpions to insects, have all evolved the same instrument: the venomous sting.

Thursday, January 5, 2023

Climate change could cause “disaster” in the world’s oceans

J. Keith Moore, UCI professor of Earth system science, says, “… unchecked global warming could lead to a shutdown of the ocean deep circulation. This would be a climate disaster similar in magnitude to complete melting of the ice sheets on land.”
Photo Credit: Steve Zylius / UCI

Climate-driven heating of seawater is causing a slowdown of deep circulation patterns in the Atlantic and Southern oceans, according to University of California, Irvine Earth system scientists, and if this process continues, the ocean’s ability to remove carbon dioxide from the atmosphere will be severely limited, further exacerbating global warming.

In a recent study published in Nature Climate Change, these researchers analyzed projections from three dozen climate models and found that the Atlantic Meridional Overturning Circulation and the Southern Meridional Overturning Circulation will slow by as much as 42 percent by 2100. The simulations suggest that under worst-case warming, the SMOC could cease entirely by 2300.

“Analysis of the projections from 36 Earth system models over a range of climate scenarios shows that unchecked global warming could lead to a shutdown of the ocean deep circulation,” said co-author J. Keith Moore, UCI professor of Earth system science. “This would be a climate disaster similar in magnitude to complete melting of the ice sheets on land.”

Wednesday, January 4, 2023

Was That Explosion Chemical or Nuclear?

From left to right: Tim Johnson, Hunter Knox, and Harry Miley bring together different perspectives to better detect underground nuclear explosions. 
Composite Image Credit: by Shannon Colson | Pacific Northwest National Laboratory

If an underground explosion occurs anywhere in the world, there is a good chance that a seismologist can pinpoint it. However, they won’t necessarily be able to tell you what kind of explosion had occurred—whether it is chemical or nuclear in nature. New research from Pacific Northwest National Laboratory (PNNL) scientists makes detecting nuclear explosions easier.

“To a seismologist, chemical and nuclear explosions look identical,” said Harry Miley, Laboratory Fellow and physicist in the National Security Directorate at PNNL. “Radionuclide detection technologies, like the PNNL-developed Xenon International and Radionuclide Aerosol Sampler/Analyzer, known as RASA, can discriminate between the two by detecting radioactive atoms that are created in nuclear explosions. However, we have very little scientific understanding of the geologic containment of these atoms following an explosion.”

When an underground explosion occurs, gases travel through fractures in the ground and escape into the atmosphere. Instruments such as Xenon International and RASA can then detect radionuclide gases, but their chemical signatures may be greatly affected by rock damage that the gases must pass through.

Tuesday, January 3, 2023

Fewer moths, more flies

Insects such as the bumblebee hoverfly Volucella bombylans appear much less frequently than before.
Photo Credit: Carolien van Oijen

The complex relationships between plants and their pollinators have changed dramatically across the last century

In the far north of the planet, climate change is clearly noticeable. A new study in Finland now shows that in parallel there have been dramatic changes in pollinating insects. Researchers from the Martin Luther University Halle-Wittenberg (MLU), the Helmholtz Centre for Environmental Research (UFZ), and the German Centre for Integrative Biodiversity Research Halle-Jena-Leipzig (iDiv) have discovered that the network of plants and their pollinators there has changed considerably since the end of the 19th century. As the scientists warn in an article published in Nature Ecology & Evolution, this could lead to plants being pollinated less effectively. This, in turn, would adversely affect their reproduction.

Their service is invaluable. The army of insects and other animals that pollinates the numerous plants of this earth has an essential function. Without these flower visitors, numerous wild plants could reproduce only poorly - or not at all. Ecosystems would thus no longer be able to function in their current form. More than three quarters of the most important crops depend on pollinators in order to be able to produce a high yield and good quality. A loss of pollinators would therefore also lead to economic losses amounting to billions.

Tuesday, December 20, 2022

Diving birds are more prone to extinction, says new study

Diving birds like puffins are highly adapted for their environment, but that means they can't adapt so well to changing conditions.
Photo Credit: Michael Blum

Diving birds like penguins, puffins and cormorants may be more prone to extinction than non-diving birds, according to a new study by the Milner Centre for Evolution at the University of Bath. The authors suggest this is because they are highly specialized and therefore less able to adapt to changing environments than other birds.

The ability to dive is quite rare in birds, with less than a third of the 727 species of water bird using this way of hunting for food.

Evolutionary scientists Joshua Tyler and Dr Jane Younger studied of the evolution of diving in modern waterbirds to investigate how diving impacted: the physical characteristics of the birds (morphology); how the species evolved to increase diversity (rate of speciation); and how prone the species were to extinction.

The study, published in Proceedings of the Royal Society B, found that diving evolved independently 14 times, and that once a group had evolved the ability to dive, subsequent evolution didn’t reverse this trait.

The researchers found that body size amongst the diving birds had evolved differently depending on the type of diving they did.

Monday, December 19, 2022

New study finds logged tropical forests are surprisingly vibrant and need protection

Logged tropical forests are surprisingly vibrant and need protection.
Photo Credit: Zoe G Davies

A new study by researchers at the University of Oxford, finds that logged rainforests are treasure-troves of healthy ecological function and should not be written off for oil palm plantations.

The study examines the flow of ecological energy across old-growth forests, logged forests and oil palm

Surveys mammal and bird species across these landscapes to calculate food energetic pathways: how photosynthetic energy cascades from sunlight to be distributed among organisms

Relative to energy flow in old-growth forests, study finds 2.5 times more total energy flows in logged forests

The study findings question the use of the word “degraded” to describe logged tropical forests

Friday, December 16, 2022

Bird Diversity Increased in Severely Burned Forests of Southern Appalachian Mountains

Forest burned in high-severity wildfire.
Photo Credit: Chris Moorman

A new study found bird diversity increased in North Carolina mountain forest areas severely burned by wildfire in 2016, reinforcing that while wildfire can pose risks to safety and property, it can be beneficial to wildlife. The study results could help forest managers better predict bird responses to wildfire, and manage forests to benefit birds.

“It’s important for us to understand the relationships between animals and wildfire dynamics as the climate changes because predictions show more of these high-severity wildfires across the landscape in the future,” said study co-author Chris Moorman, professor of forestry and environmental resources at North Carolina State University.

Wildfires burned more than 235 square miles of forest in the southern Appalachians in the fall of 2016, following a period of dry conditions and acts of arson. In the study published in the journal Forest Ecology and Management, researchers tracked different levels of burn severity in three forest regions of the Nantahala National Forest in western North Carolina.

Thursday, December 15, 2022

Greenland’s Glaciers Might Be Melting 100 Times As Fast As Previously Thought

A melting glacier on the coast of Greenland.
Photo Credit: Dr. Lorenz Meire, Greenland Climate Research Center.

A computer model has been created by researchers at the Oden Institute for Computational Engineering and Sciences at The University of Texas at Austin that determines the rate at which Greenland’s glacier fronts are melting.

Published in the journal Geophysical Research Letters, the model is the first designed specifically for vertical glacier fronts – where ice meets the ocean at a sharp angle. It reflects recent observations of an Alaskan glacier front melting up to 100 times as fast as previously assumed. According to the researchers, the model can be used to improve both ocean and ice sheet models, which are crucial elements of any global climate model.

“Up to now, glacier front melt models have been based on results from the Antarctic, where the system is quite different,” said lead author Kirstin Schulz, a research associate in the Oden Institute’s Computational Research in Ice and Ocean Systems Group (CRIOS). “By using our model in an ocean or climate model, we can get a much better idea of how vertical glacier fronts are melting.”

Scientists find iron cycling key to permafrost greenhouse gas emissions

Iron content gives a reddish hue to an area of ponded water in the Arctic permafrost. ORNL scientists are exploring the importance of the iron cycle on how greenhouse gases are released from thawing Arctic soils.
Photo Credit: David Graham/ORNL, U.S. Dept. of Energy

The interaction of elemental iron with the vast stores of carbon locked away in Arctic soils is key to how greenhouse gases are emitted during thawing and should be included in models used to predict Earth’s climate, Oak Ridge National Laboratory scientists found.

Researchers set out to explore and model the chemistry going on as the Arctic permafrost thaws in response to global warming. Northern permafrost soils contain an estimated 1,460 billion to 1,600 billion metric tons of organic carbon — about twice as much as in the atmosphere, according to the National Oceanic and Atmospheric Administration.

Chemical processes in the soil control how organic matter decomposes and is stored in soils and whether it converts to carbon dioxide or the more powerful greenhouse gas methane when released into the atmosphere.

Arctic soils are typically organic-rich and often have a high iron content, frequently visible as rusty deposits in flooded soils in the region, said ORNL modeler and principal investigator Benjamin Sulman. But current Earth system models do not take iron cycling into account when predicting the climate-warming potential of thawing permafrost.

Early green, early brown – climate change leads to earlier senescence in alpine plants

Alpine plants that start to grow earlier also start to age earlier. As is the case with the alpine vegetation in these containers, which were exposed to summer weather several months before the snow melted photograph taken in July
Photo Credit: P. Möhl

Global warming is leading to longer growing seasons worldwide, with many plants growing earlier in spring and continuing longer in autumn thanks to warmer temperatures—so is the general opinion. Now, however, plant ecologists at the University of Basel have been able to show that this is not the case for the most common type of alpine grassland in the European Alps, where an earlier start leads to earlier aging and leaves the grassland brown for months.

Spring 2022 was extremely warm, giving many plants an early start to the growing season. And the Swiss Alps were no exception, with the snow cover melting early and the underlying vegetation being quickly roused into growth. Researchers at the Department of Environmental Sciences at the University of Basel have investigated how such an early start affects the plants’ further development.

For their study, they removed intact blocks of alpine grassland and placed them in walk-in climate chambers at Basel’s Botanical Institute. Here, they left the vegetation to overwinter artificially in cold darkness, and then switched some of the blocks to summer conditions in February. A second group was left in the cold dark until April, before summer was introduced here as well. The researchers compared the growth and aging of these plants with their neighbors growing naturally at an elevation of 2,500 meters, which did not emerge from the snow until late June.

Wednesday, December 14, 2022

Paris Agreement temperature targets may worsen climate injustice for many island states

A comparison of global greenhouse gas emissions from 1990 – 2018 shows the low emissions contribution of AOSIS nations (blue) and increasing levels of total global emissions (red).
Illustration Credit: Sadai et al., 10.1029/2022EF002940

While the world focuses on limiting the rise in global temperature to 1.5 or 2 degrees Celsius over the preindustrial average, increasing meltwater from ice sheets presents an existential threat to the viability of island and coastal nations throughout the world. Now, research from the University of Massachusetts Amherst, recently published in the journal Earth’s Future, shows that even the most optimistic temperature targets can lead to catastrophic sea-level rise, which has already begun and will affect low-lying nations for generations to come.

While rising temperatures are having many deleterious effects on global ecosystems, economies and human wellbeing, an interdisciplinary team of researchers at the University of Massachusetts emphasize that temperature alone is not a sufficient basis for climate policy. 

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