Tag Archives: sea

Titan’s largest methane sea is over 1000 feet deep, says a new paper

Titan’s seas should be deep enough for a robotic submarine to wade through, a new paper explains. This should help pave the way towards our exploration of Titan’s depths.

Radar map of the polar region of Saturn’s moon Titan. Image credits NASA / JPL-Caltech.

Fancy a dip? Who doesn’t. But if you ever find yourself on Titan, Saturn’s biggest moon, you should stay away from swimming areas. A new paper reports that the Kraken Mare, the largest body of liquid methane on the moon’s surface is at least 1,000 feet deep near its center, making it both very deep and very cold.

While that may not be very welcoming to humans, such findings help increase our confidence in plans of exploring the moon’s oceans using autonomous submarines. It was previously unknown if Titan’s methane seas were deep enough to allow such a craft to move through.

Faraway seas

“The depth and composition of each of Titan’s seas had already been measured, except for Titan’s largest sea, Kraken Mare—which not only has a great name, but also contains about 80% of the moon’s surface liquids,” said lead author Valerio Poggiali, a research associate at the Cornell Center for Astrophysics and Planetary Science (CCAPS).

Titan is a frozen moon that shines with a golden haze as sunlight glints on its nitrogen-rich atmosphere. Beyond that, however, it looks surprisingly Earth-like with liquid rivers, lakes, and seas sprawling along its surface. But these are not made of water — they’re filled with ultra-cold liquid methane.

The findings are based on data from one of the last Titan flybys made during the Cassini mission (on Aug. 21, 2014). During this flyby, the probe’s radar was aimed at Ligeia Mare, a smaller sea towards the moon’s northern pole. Its goal was to understand the mysterious “Magic Island” that keeps disappearing and then popping back up again.

Its radar altimeter measured the liquid depth at Kraken Mare and Moray Sinus (an estuary on the sea’s northern shore). The authors of the paper, made up of members from both NASA’s Jet Propulsion Laboratory and Cornell University, used this data to map the bathymetry (depth) of the sea. They did this by tracking the return time on the radar’s signal for the liquid’s surface and the sea bottom while taking into account the methane’s effect on the signal (it absorbs some of the energy from the radio wave as it passes through, in essence dampening it to an extent).

Colorized mosaic of Titan’s Kraken Mare. Liquids are blue and black, land areas appear yellow to white. The surface was mapped using radar data from NASA’s Cassini. Image credits NASA / JPL-Caltech / Agenzia Spaziale Italiana / USGS via Wikimedia.

According to them, the Moray Sinus is about 280 feet deep, and the Kraken Mare gets progressively deeper towards its center. Here, the sea is too deep for the radar signal to pierce through, so we don’t know its maximum depth. The data also allowed us some insight into the chemical composition of the sea: a mix of ethane and methane, dominated by the latter. This is similar to the chemical composition of Ligeia Mare, Titan’s second-largest sea, the team explains. It might seem inconsequential, but it’s actually a very important piece of information: it suggests that Titan has an Earth-like hydrologic system.

Kraken Mare (‘mare’ is Latin for ‘sea’) is our prime choice for a Titan-scouting submarine due to its size — it is around as large as all five of America’s Great Lakes put together. We also have no idea why this sea doesn’t just evaporate. Sunlight is about 100 times less intense on Titan than Earth, but it’s still enough to make the methane evaporate. According to our calculations, this process should have completely depleted the seas in around 10 million years, but evidently, that didn’t happen. This is yet another mystery our space-faring submarine will try to answer.

“Thanks to our measurements,” he said, “scientists can now infer the density of the liquid with higher precision, and consequently better calibrate the sonar aboard the vessel and understand the sea’s directional flows.”

The paper “The Bathymetry of Moray Sinus at Titan’s Kraken Mare” has been published in the journal Journal of Geophysical Research: Planets.

The effects of sea-level rise on communities are complex and unpredictable, says a new study

Climate change stands poised to melt the planet’s ice caps and raise sea levels worldwide, with dramatic effects for human society. But these effects won’t be felt all at once, a new study suggests.

Image credits Makoto Seimori.

The research, led by the University of Exeter in partnership with Cornwall Archaeological Unit, Cardiff University and 14 other institutes, focused on the Isles of Scilly, a group of islands of the UK’s south-west coast. The 140 islands of today are the remnants of a single large island which was gobbled up by the seas less than 1,000 years ago, the team reports. But the changes in land area and the shifts in human cultures associated with them took place at variable rates, they add, and were often ‘out of step’ with the average rate of sea-level rise.

Such findings showcase that the effects of rising seas are more complex and unpredictable than we assume, and will be much further reaching than simply forcing coastal communities to relocate.

Rising seas flood all boats

“When we’re thinking about future sea-level rise, we need to consider the complexity of the systems involved, in terms of both the physical geography and the human response” said lead author Dr. Robert Barnett, of the University of Exeter. “The speed at which land disappears is not only a function of sea-level rise, it depends on specific local geography, landforms, and geology.”

“Human responses are likely to be equally localized. For example, communities may have powerful reasons for refusing to abandon a particular place.”

The team studied the process through which the old island turned into the current cluster of 140 islands, which overall lasted some 12,000 years. They first developed a sea-level curve for the Isles over this time (a chart that shows sea level over time). Then, the team analyzed how these changes influenced the landscape, vegetation, and human populations from archaeological evidence as well as samples of pollen and charcoal collected by the Lyonesse Project (2009 to 2013).

The findings suggest that between 4,000 and 5,000 years ago, the island was rapidly becoming submerged. The inhabitants were seemingly trying to adapt to the changes in their landscape rather than abandoning the area altogether. Around 4,400 years ago, during the Bronze Age, the island had a permanent population that showed “a significant acceleration of activity”.

Land losses during this time were quite quick despite sea levels rising quite slowly, because a large part of Scilly at this point was relatively flat and close to sea level. According to the team, land here was being lost at a rate of around 10,000 sq. meters per year (a 100 by 100 meter square), roughly equivalent to a large rugby stadium. Exactly why these early inhabitants weren’t scared by higher seas is unclear; however, the team believes that they created more opportunities for fishing, the collection of shellfish, or the hunting of marine bird species. It’s possible that much of this lost land developed into intertidal habitats (exposed at low tide and submerged at high tide), which were still useful and traversable to coastal communities.

After around 4,000 years ago, the island was progressively submerged, even during times with lower rates of sea-level rise (around 1 mm per year).

“It is clear that rapid coastal change can happen even during relatively small and gradual sea-level rise,” said Dr. Barnett.”The current rate of mean global sea-level rise (around 3.6 mm per year) is already far greater than the local rate at the Isles of Scilly (1 to 2 mm per year) that caused widespread coastal reorganization between 5,000 and 4,000 years ago.”

“It is even more important to consider the human responses to these physical changes, which may be unpredictable. As can be seen today across island nations, cultural practices define the response of coastal communities, which can result in polarised agenda, such as the planned relocation programs in Fiji versus the climate-migration resistance seen in Tuvalu.”

Sea level rise led to new marine resources becoming available for communities on the island of Scilly, but the team believes it is “unlikely” that this mechanism will prove enough to support today’s communities as they become affected or displaced by rising sea levels.

“More certain though, is that societal and cultural perspectives from coastal populations will be critical for responding successfully to future climate change,” says Dr. Barnett.

The study “Nonlinear landscape and cultural response to sea-level rise,” has been published in the journal Science Advances.

The iconic ‘Dumbo’ octopus stars in the deepest-ever octopus sighting

The adorable cephalopod has been photographed on the bottom of the Indian Ocean in the Java Trench, at around 7,000 meters of depth.

Image credits amieson, A.J., Vecchione, (2020), Mar Biol.

This is roughly 2 kilometres deeper than any previous reliable sighting of a cephalopod, the family that includes octopus and squids. Given that we now know how deep these animals can live — seemingly very comfortably, too — the findings “increase the potential benthic (ocean floor) habitat available to cephalopods from 75 to 99% of the global seafloor”.

The deep end

The researchers who spotted the boneless animal say it’s a species of “Dumbo” octopus, so named due to its distinctive side fins. Due to their size and shape, they’re very reminiscent of an elephant’s ears, most notably to those of Disney’s 1940s’ animated elephant Dumbo.

Still, spotting the octopus at this depth was no mean feat. Lead author Dr Alan Jamieson from the School of Natural and Environmental Sciences, Newcastle University is a pioneer of the use of “landers” for deep-sea exploration. These landers are crew-less craft, in essence large metal frames outfitted with various instruments that are dropped overboard and land on the seafloor. Once there, they observe their surroundings and record any passers-by.

And record they did. The lander picked up two octopuses, a 43-cm-long one at a depth of 5,760m and the other (35 cm) at 6,957m. Based on their physionomy, Dr. Jamieson and his co-author Michael Vecchione from the NOAA National Systematics Laboratory are confident that they belong to the Grimpoteuthis family, the group commonly known as the Dumbo octopuses.

God, it’s so cute.
Image credits amieson, A.J., Vecchione, (2020), Mar Biol.

Further down, the landers also spotted octopus fragments and eggs. The study provides the deepest-ever sightings of cephalopods. Previously, the deepest reliable sighting was a 50-year-old black-and-white photograph of one such animal taken at a depth of 5,145m.

For starters, it’s impressive that anything can live at such depths, where pressure is literally crushing.

“They’d have to do something clever inside their cells. If you imagine a cell is like a balloon — it’s going to want to collapse under pressure. So, it will need some smart biochemistry to make sure it retains that sphere,” Dr. Jamieson explained.

“All the adaptations you need to live at pressure are at the cellular level.”

Furthermore, it helps fill out our understanding of hoe octopuses live. The authors explain that the study shows that such animals can (potentially) live across 99% of the global seafloor, as the Java Trench is one of the deepest points on Earth.

The paper “First in situ observation of Cephalopoda at hadal depths (Octopoda: Opisthoteuthidae: Grimpoteuthis sp.)” has been published in the journal Marine Biology.

Microplastics are all over the place, even in the sea breeze

Global levels of plastic pollution have been increasing ever since plastic products gained commercial popularity in the 1930s. This has created one of the biggest environmental problems of our time.

Credit Wikipedia Commons

While most research has generally assumed that once plastics enter the ocean they are going to stay there, that’s not necessarily the case. A new study suggests that plastic particles can transfer from seawater to the atmosphere and get carried away by the breeze.

Researchers at the University of Strathclyde and the Observatoire Midi-Pyrénées at the University of Toulouse found fragments of plastics in sea spray, suggesting that they are ejected from the seawater in “bubbles”.

“Sea breeze has traditionally been considered ‘clean air’ but this study shows surprising amounts of microplastic particles being carried by it. It appears that some plastic particles could be leaving the sea and entering the atmosphere,” Steve Allen, who co-led the study, told The Guardian.

The “bubble burst ejection” of particles in sea fog or spray, described by Allen “like soda in a glass when it hits your nose”, is a well-known phenomenon. But the new study is the first to show that microplastics are ejected from the ocean through this mechanism. “The ocean is giving the plastic back to us,” Allen said.


Plastic debris, such as plastic bags and bottles, breaks down into smaller microplastic in the sea, often invisible to the eye. The microplastics in sea spray were between 5 and 140 micrometers in size. The researchers estimated that up to 136,000 tons of microplastics could be blown onshore by sea spray every year.

Deonie Allen, the study’s co-research lead, told The Guardian that this was the result of “mismanaged waste that comes from the terrestrial environment”. She said the findings could help answer the question of where “missing” oceanic plastic goes after being dumped into the sea, a mystery scientists have been trying to solve for years.

“The transport mechanism is quite complicated” said Allen. “We know plastic comes out of rivers into the sea. Some goes into gyres, some sinks and goes into the sediment, but the quantity on the sea floor doesn’t match the amount of plastic that would make up this equation. There’s a quantity of missing plastic.”

The researchers captured water droplets from sea spray at Mimizan beach in Aquitaine, on the south-west coast of France using a “cloud catcher” and filters set up on top of a sand dune. They analyzed the water droplets for microplastics, taking samples at various wind directions and speeds.

The marine environment has generally been considered a microplastic sink. Earlier studies have identified plastic moving from cities to rivers, rivers to the sea, and — most recently — atmospheric transport of plastic across terrestrial environments out to sea.

An estimated 8 million tons of plastic enters the sea from land and coasts every year. One study estimates just 240,000 tones floats on the surface, leaving us to wonder where the rest goes. Various plastic ocean transport models have suggested “leaky basins” to explain areas that do not contain the predicted quantities of plastic.

The study was published in the journal PLOS ONE.

We could see up to 1.3m of sea-level rise by 2100 if we don’t take action now

A new study says we should be expecting an average sea-level rise in excess of 1 meter by 2100 and 5 meters by 2300 if we don’t meet current targets for the reduction of greenhouse gas emissions.

Image via Pixabay.

The analysis used projections compiled by over 100 international experts to estimate changes in sea levels under low- and high-emission scenarios, the team explains, in order to help policymakers have a better understanding of “the state of the science” on this threat.

The waters are coming

“The complexity of sea-level projections, and the sheer amount of relevant scientific publications, make it difficult for policymakers to get an overview of the state of the science,” says Professor Benjamin Horton, Acting Chair of Nanyang Technological University, Singapore (NTU Singapore) Asian School of the Environment, who led the survey.

“To obtain this overview, it is useful to survey leading experts on the expected sea-level rise, which provides a broader picture of future scenarios and informs policymakers so they can prepare necessary measures.”

The most optimistic scenario analyzed in this paper considered that global warming would only increase temperatures by 2 degrees Celsius above pre-industrial levels, which would translate to a rise of 0.5 meters (roughly 2 feet) by 2100, and 0.5 to 2 meters by 2300. The high-emission scenario would involve 4.5 degrees Celsius of warming and would cause between 0.6 to 1.3 meters (2 to 4 feet) sea rise by 2100, and 1.7 to 5.6 meters by 2300.

These estimations exceed those of the International Panel on Climate Change (IPCC), who set the current targets under the Paris Agreement. Researchers from The University of Hong Kong, Maynooth University (Ireland), Durham University (UK), Rowan University (U.S.), Tufts University (U.S.), and the Potsdam Institute for Climate Impact Research (Germany) took part in this study. They were chosen as they are some of the most active publishers or scientific studies on the topic (they all had at least six published papers pertaining to sea-level rise since 2014).

The large difference in sea level rise seen in this paper “provides a great deal of hope for the future, as well as a strong motivation to act now to avoid the more severe impacts of rising sea levels,” according to Dr. Andra Garner, Assistant Professor of Environmental Science at Rowan University and co-author of the study.

Still, the findings also underscore just how important it is for policy to be set in place in order to limit emissions and sea-level rise. How bad the outcome is depends entirely on how we act, and the decisions we make right now.

However, despite the sheer wealth of expertise that went into the study, there are still uncertainties. The team points to the Greenland and Antarctic Ice Sheets as the largest unknowns, as their behavior can have dramatic effects on how sea levels evolve in the future. Both of these ice sheets are key reference points for climate change and increases in sea levels, as they hold important quantities of water — and they’re both melting at much higher rates than they would naturally.

Yet, not all is lost. Climate systems have a great deal of inertia to them (as do all systems working on such scales) but taking proactive measures to limit greenhouse gas emissions would still have a significant effect.

So while the worst-case scenario definitely does seem bleak, it’s in no way out of our hands. We can choose to make things better, to limit the impact we have on the planet and the repercussions that will have on our society in the future.

The paper “Estimating global mean sea-level rise and its uncertainties by 2100 and 2300 from an expert survey,” has been published in the journal Climate and Atmospheric Science.

Sea level rise could displace 13 million Americans by 2100

New research from the University of Southern California (USC) looks at how rising sea levels will affect population dynamics in the US. By their estimates, 13 million people will be displaced by 2100, placing extreme strain on several cities throughout the country.

Image credits NASA.

Global warming is driving sea-levels up through two main mechanisms: increased water inflow from melting ice sheets and glaciers, and the thermal expansion of warming water. Human populations tend to mostly gravitate around coasts and waterways and, as such, it’s estimated that sea-level rise will destroy hundreds of thousands of homes in just a few decades. Current estimates place sea level increase by the end of the century at a 6-foot mark, which would redraw the coastlines of Florida, North Carolina, Massachusetts, Louisiana, and New Orleans.

Which begs the question — where will the displaced go to?

Water damage

“Sea level rise will affect every county in the US, including inland areas,” says Bistra Dilkina, an Assistant Professor of Computer Science from the USC’s Center for AI for Society.

“We hope this research will empower urban planners and local decision-makers to prepare to accept populations displaced by sea-level rise. Our findings indicate that everybody should care about sea-level rise, whether they live on the coast or not. This is a global impact issue”.

In the aftermath of Hurricane Harvey (2017), displaced residents from the coast of Texas flocked inland. The team explains that this event showcases what could happen, on a much wider scale, within a few decades. Some 13 million people could be forced to relocate due to rising sea levels by 2100 in the US alone, they found, which would place an enormous strain on the population centers they migrate to. The strain of this environmental disaster will thus ripple throughout the country, not just on the affected coastlines, as people move inland. Among the effects, the team lists more competition for jobs, increased housing prices, and huge pressure on infrastructure and social systems.

The team is the first to use machine learning to project future migration patterns resulting from sea-level change. According to their findings, land-locked cities such as Atlanta, Houston, Dallas, Denver, and Las Vegas will see the highest number of refugees. Suburban areas in the Midwest are also likely to see a disproportionately large number of refugees relative to their current local populations.

For the study, the team took existing sea-level projections and combined them with population data and their projections until the end of the century. Migration pattern data recorded after Hurricane Katrina and Hurricane Rita was used to train machine learning models to predict where people would relocate in the simulated world.

“We talk about rising sea levels, but the effects go much further than those directly affected on the coasts,” said Caleb Robinson, a visiting doctoral researcher from Georgia Tech and the study’s first author.

“We wanted to look not only at who would be displaced, but also where they would go.”

Inland areas immediately adjacent to the coast bore the brunt of the migration, the team found, as did urban areas in the southeastern US. However, their model showed that more migrants would flock to Houston or Dallas than previous studies on the topic — these identified Austin as the top destination for climate refugees from the southeastern coast.

The study suggests that climate-change-induced migrations won’t necessarily follow previous patterns of movement. The authors hope that their findings will help policymakers and city planners reinforce infrastructure to ensure that the influx of refugees will have a positive impact on local economies and communities.

“When migration occurs naturally, it is a great engine for economic activity and growth,” said co-author Juan Moreno Cruz, an economist and professor at the University of Waterloo. “But when migration is forced upon people, productivity falls and human and social capital are lost as communities are broken apart.”

“Understanding these migration decisions helps economies and policy makers prepare for what is to come and do as much as possible to make the influx of migration a positive experience that generates positive outcomes.”

The paper “Modeling migration patterns in the USA under sea level rise” has been published in the journal PLOS ONE.

Greenland is losing ice seven times faster than in the 1990s

Greenland’s rate of ice loss is increasing faster than expected, a new metastudy reports.

The increased influx of water from Greenland’s ice sheet puts us on track for sea-level rise consistent with the Intergovernmental Panel on Climate Change’s (IPCC) high-end climate warming scenario. Projections for this scenario estimate that coastal flooding will displace 400 million people by 2100.

Image credits Jean-Christophe Andre.

The study is a collaboration between 96 polar scientists from 50 international organizations — The Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) team — and takes the most complete look at Greenland’s long-term ice loss to date. It combined 26 separate surveys to track changes in the ice mass of Greenland between 1992 and 2018. Data from 11 different satellite missions was used to measure the ice sheet’s changing volume, flow, and mass.

Melting quick

“On current trends, Greenland ice melting will cause 100 million people to be flooded each year [by 2100], so 400 million in total due to all sea level rise,” says Professor Andrew Shepherd at the University of Leeds, one of the study’s co-lead authors.

Melt rate in Greenland has risen from 33 billion tons, on average, per year in the 1990s to 254 billion tons per year over the last decade. In total, the island lost roughly 3.8 trillion tons of ice since 1992.

The IPCC mid-warming scenario set out in 2013 estimated 60 centimeters of sea-level rise by 2100, with associated coastal flooding displacing an estimated 360 million people. The rates of melt reported on in this study push those estimates by an additional 5 to 12 cm — consistent with the projection for the high-warming climate scenario.

“As a rule of thumb, for every centimeter rise in global sea level another six million people are exposed to coastal flooding around the planet,” Professor Shepherd explains.

The report shows that half of the ice losses recorded between 1992 and today have been caused by higher average temperatures, which promoted surface melting. The rest, around 48% of the total ice mass lost, was caused by increased glacier flow into the ocean due to warmer waters. Melting peaked 335 billion tonnes per year in 2011 but has since decreased to 238 billion tonnes per year “as atmospheric circulation favored cooler conditions”.


The team notes that this lower rate is still seven times higher than that in the 1990s, and that the dataset didn’t include all of 2019. Higher rates of melt expected in the summer could push Greenland to see record quantities of ice loss.

“Satellite observations of polar ice are essential for monitoring and predicting how climate change could affect ice losses and sea level rise” said Erik Ivins at NASA’s Jet Propulsion Laboratory in California, and co-lead author of the study.

Researchers from the European Space Agency (ESA) and the US National Aeronautics and Space Administration (NASA) also took part in the IMBIE report.

The paper “Mass balance of the Greenland Ice Sheet from 1992 to 2018” has been published in the journal Nature.

New fossil rewrites the evolutionary history of sea lilies

New research into the evolutionary history of sea lilies is setting wrong assumptions from the 1800’s right.

A modern-day sea lily.
Image credits Ryan Somma / Flickr.

Sea lilies, or ‘crinoids’, are part of an ancient lineage. Our earliest evidence of them come from around 480 million years ago, way before the dinosaurs popped in. Sea lilies are related to sea urchins and starfish, and are formed from a long slender stalk and feathery arms.

Over the last two centuries, the prevailing theory around sea lilies was that they were directly descended from ancient organisms that resembled them in shape and structure (cystoids). However, that theory has been challenged over time. The current paper aims to put that debate to rest by describing a newly-discovered species of extinct sea lily, and how it fits in the family’s evolutionary history.

A song of plates and lilies

“These early fossils provide new key evidence showing that what we had thought about the origin of sea lilies since 1846 is wrong,” says Tom Guensburg, the paper’s lead author and a research associate at the Field Museum in Chicago. “It’s not very often that we’re challenging ideas that are almost two hundred years old.”

Crinoids spend their adult lives anchored to the seafloor. Their stalks end in a cluster of feather- or fern-like arms that handle feeding: they filter plankton floating around in the water. They come in many colors and quite a variety of shapes and sizes, making them look very flower-like (hence the name).

“They look plant-like, but when you actually look at their bodies, you find all the usual anatomy of complex animals like a digestive tract and nervous system–they’re closer to vertebrates, and us, than almost any other invertebrate animals,” says Guensburg.

In 1846, researchers working on piecing together the family tree of the echinoderms — a phylum including sea lilies, starfish, sand dollars, sea urchins, sea cucumbers, and a number of extinct species — found cystoid fossils and assumed they must be closely related to today’s sea lilies. Around 100 years later, the team writes, this theory was called into question, as the similarities between the two species seemed to only be superficial.

In the paper, Guensburg and his colleagues describe a new kind of fossil sea lily named Athenacrinus broweri after the Greek goddess Athena. They chose this name as Athena is “often depicted with rangy, almost gangly limbs on ancient Greek vases”, and the fossil’s arms resemble that.

Athenacrinus broweri fossil.
Image credits Field Museum, Kate Golembiewski.

Athenacrinus‘ arm structure helped the team piece together the evolutionary history of crinoids, which is linked to some of the earliest-known echinoderms, some of them up to 515 million years old. This group of animals hadn’t evolved arms yet, but their bodies did have plate structures seen in the arms of early crinoids. Past 450 million years ago, these structures had completely disappeared in sea lilies, being replaced with a different type of arm plating.

What modern sea lilies do have, the team explains, are tissue remnants inherited from echinoderms. As such, the team says that that early sea lilies from 480 million years ago are the missing link between their earliest ancestors and what we see in living crinoids. Cystoids, in contrast, have different arm structures entirely — suggesting that crinoids and cystoids are related only at the most primitive level in echinoderm history, when their lineages split.

“These new fossils provide for the first time an accurate picture of what the earliest crinoid arms were like, and they are unlike any cystoid in important ways,” says Guensburg; “No cystoid has such anatomy.”

“One of the most fascinating branches of the tree of life, echinoderms, needs rearranging,” he notes. “That’s a big deal.”

The paper “Athenacrinus n. gen. and other early echinoderm taxa inform crinoid origin and arm evolution” has been published in the Journal of Paleontology.

Stop climate change or the Emperor penguins die, a new paper warns

Unless we get a grip on climate heating, the emperor penguin is going the way of the dodo — extinct.

Image credits Christopher Michel / Flickr.

An international study led by researchers at the Woods Hole Oceanographic Institution (WHOI) reports that warming climate conditions might cause emperor penguins (Aptenodytes forsteri) to become extinct by the end of the century.

The Emperor’s new environment

“If global climate keeps warming at the current rate, we expect emperor penguins in Antarctica to experience an 86% decline by the year 2100,” says Stephanie Jenouvrier, a seabird ecologist at WHOI and lead author on the paper.

“At that point, it is very unlikely for them to bounce back.”

Emperor penguins live and die by sea ice, which is where they breed and molt. The animals build their colonies on spans of ice that satisfy very specific conditions: it must be locked to the Antarctic shoreline but close to open seawater (giving the birds access to food). Climate heating is melting sea ice, however, which effectively destroys the birds’ habitat, food access, and ability to reproduce.

For their study, the team combined a global climate model (created by the National Center for Atmospheric Research, NCAR) and a model of the penguin populations themselves. The first gave the team a rough idea of how sea ice will evolve in the future, especially in terms of where and when it will form or melt in the future. The second one worked to predict how colonies might react to the changes in their environment.

“We’ve been developing that penguin model for 10 years,” says Jenouvrier. “It can give a very detailed account of how sea ice affects the life cycle of emperor penguins, their reproduction, and their mortality. When we feed the results of the NCAR climate model into it, we can start to see how different global temperature targets may affect the emperor penguin population as a whole.”

The compound model was then used to examine three different scenarios. The first assumes an increase in global average temperatures of only 1.5 degrees Celsius (the goal set out by the Paris climate accord). The second involves a temperature increase of 2 degrees Celsius. The final scenario assumes no action was taken against climate change, leading to temperature increases of 5 to 6 degrees Celsius.

The first one led to a loss of around 5% of sea ice by 2100, causing a roughly 20% drop in the penguin population. The 2-degree warming scenario led to around 15% ice loss and a 30% drop in penguin numbers. The business as usual scenario was by far the most damaging, leading to almost complete loss of the penguin colonies.

“Under that scenario, the penguins will effectively be marching towards extinction over the next century,” she says.

The paper “The Paris Agreement objectives will likely halt future declines of emperor penguins” has been published in the journal Global Change Biology.

Sea level rise by 2300 is unavoidable, despite the Paris agreement

We’re set on the path of rising sea levels, even if the pledges made for the Paris climate agreement are met and global temperatures stabilize, a new paper reports.

Image via Pixabay.

The Paris agreement on climate change mitigation was adopted in December 2015 and aims to limit the rise of global average temperatures to a maximum of 2°C compared to pre-industrial levels. The ideal scenario under the agreement would be to limit this figure to 1.5°C, and the countries that signed into the agreement are expected to make efforts towards this goal.

While a successful Paris agreement would do wonders for our efforts against climate heating and environmental degradation, we’re already set for rising sea levels around the world by 2300, a new study reports.

We’re already there

“Even if we were to meet these initial goals of the Paris agreement, the sea level commitment from global warming will be significant,” said Peter Clark, an Oregon State University climate scientist and a co-author of the study.

“When we pump more carbon into the atmosphere, the increase in temperature is almost immediate. But sea level rise takes a lot longer to respond to that warming. If you take an ice cube out of the freezer and put it on the sidewalk, it takes some time to melt. The bigger the ice cube, the longer it takes to melt.”

The authors say this is the first effort to quantify how sea levels will rise from carbon emissions (both past and future) released since the agreement was signed. In the first 15 years following the agreement, they report, will cause a rise of roughly 20 centimeters (7.9 in) by 2300. The estimate does not take into account the effect of irreversible melting in parts of the Antarctic ice sheet, the team adds, which is already underway.

A one-meter rise is expected by 2300, caused by emissions dating back to the year 1750. Around 20% of that rise can be traced back to emissions released since after the Paris agreement was signed. Around half of it (so 10% of the total projected rise) is attributable to the world’s top five polluters, the team found: the United States, China, India, Russia, and the European Union

Sea level rise is a huge threat to coastal ecosystems and human communities, with the potential to affect and/or displace hundreds of millions around the world (coastal areas are the most heavily-inhabited regions on Earth). Sea level rise is mostly driven by melt from glaciers and ice sheets draining into the ocean. But these are massive structures strewn all over the world, and they each respond to climate heating in their own time, ranging from decades to millennia.

“Much of the carbon dioxide we’ve emitted into the atmosphere will stay up there for thousands of years,” said Clark, who is on the faculty of OSU’s College of Earth, Ocean, and Atmospheric Sciences.

“So our carbon emissions this century are not only committing our planet to a warmer climate, but also to higher sea levels that will also persist for thousands of years.”

The paper “Attributing long-term sea-level rise to Paris Agreement emission pledges” has been published in the journal Proceedings of the National Academy of Sciences.

Researchers have solid proof that the sea is rising — five islands have been lost so far, six more underway in the Solomon Islands

Sea level rise threatens to gulp up coasts and islands in the future; a new study shows that the future is already here in that regard.

A vista from Visale, Solomon Islands.
Image via Wikimedia.

At least five islands in the Solomon Islands chain have been completely lost to rising seas and coastal erosion. These islands have completely vanished under the surface, and the authors note at least two cases where entire human populations have had to relocate to avoid the waves.

This is the first scientific evidence that confirms anecdotal accounts from across the Pacific of the dramatic impacts of climate change on coastlines and communities.

Et tu, Atlantis?

“Using time series aerial and satellite imagery from 1947 to 2014 of 33 islands, along with historical insight from local knowledge, we have identified five vegetated reef islands that have vanished over this time period and a further six islands experiencing severe shoreline recession,” the authors write.

The five lost islands ranged in size from one to five hectares and supported dense tropical vegetation, the study explains. Some of the islands that are in the process of disappearing are inhabited. Nuatambu Island, home to 25 families, has lost more than half of its habitable area (and 11 houses) into the sea since 2011.

The findings are both surprising and worrying, as previous research had estimated that islands in the Pacific can keep pace with sea-level rise, and maybe even expand. However, the team notes that those studies focused on areas of the Pacific where sea levels rise by only 3-5 mm per year – broadly in line with the global average of 3 mm per year. The Solomon Islands have experienced a much more rapid sea level rise over the last two decades, at almost three times the global average.

This higher local rate is partly the result of natural climate variability. However, they’re a good indication of how fast sea levels will rise around the world in a warmer future. While natural variations and geological activity will affect future rates of sea level rise, if we don’t dramatically slash greenhouse emissions, what’s happening in the Solomons right now will become the new normal.

It’s not just that the sea is creeping up — it’s also slowly breaking apart the islands. The team says that rates of coastal erosion in the Solomon Islands are ‘dramatic’ and point to increased wave energy as the likely culprit. Those islands that had to contend with both higher wave energy and sea-level rise fared the worst out of all the islands in the study. Around 12 islands in a low wave-energy area showed very little change in their shorelines, while out of 21 exposed islands 5 disappeared completely and 6 showed substantial levels of erosion.

Twelve islands that were studied in a low wave energy area of Solomon Islands experienced little noticeable change in shorelines despite being exposed to similar sea-level rise. However, of the 21 islands exposed to higher wave energy, five completely disappeared and a further six islands eroded substantially.

The paper “Interactions between sea-level rise and wave exposure on reef island dynamics in the Solomon Islands” has been published in the journal Environmental Research Letters.

Greenland set to accelerate sea level change in the near future

Greenland’s contribution to sea-level rise is increasing, as climate change makes the region release meltwater into the ocean.

Image via Pixabay.

Greenland’s ice sheet is experiencing an increase in ice slab thickness at its interior regions. These ice sheets are normally porous, allowing meltwater to percolate (drain through) them, but the extra thickness makes them impermeable — so all the meltwater is draining into the ocean.

The process could see the country’s contribution to sea level rise increase by as much as 2.9 inches by 2100.

Thicc ice

“Even under moderate climate projections, ice slabs could double the size of the runoff zone by 2100,” said Mike MacFerrin, a CIRES (Cooperative Institute for Research In Environmental Sciences) and University of Colorado Boulder researcher who led the new study. “Under higher emissions scenarios, the runoff zone nearly triples in size.”

Runoff from ice slabs only amounts to a one-millimeter increase in global sea levels so far, the team explains, but that contribution will expand substantially under climate warming.

In the year 2000, Greenland’s runoff zone — the region of the ice sheet where runoff contributes to sea level rise — was roughly equivalent to the size of New Mexico. Between 2001 and 2013, it expanded by an average of two American football fields per minute, reaching roughly 65,000 sq km.

Even under a moderate emissions scenario, the team adds, it could reach the size of Colorado by 2100. That would raise sea levels by an extra 7-33 mm (one-quarter to one inch) by the same timeframe. Under a high emissions scenario, the situation looks even bleaker: the runoff zone could increase by the size of Texas, according to the new paper, contributing an extra 17-74 mm (half-inch to nearly three inches) of sea-level rise.

The runoff estimates from ice slabs are in addition to other sources of sea-level rise from Greenland, such as calving icebergs.

The team explains that Greenland’s ice sheets are made of layers with different textures. Fresh snow that falls each winter either melts into surface lakes or builds-up and helps compact older snow into glacial ice. Snow that partially melts over summer later re-freezes into thin ice “lenses” between 2 to 5 mm (one or two inches) thick within the compacted snow.

Normally, meltwater can percolate through and around ice lenses, refreezing in place without running off to sea. As mean temperatures over the Arctic increase and melting events become more frequent and extreme, however, these ice lenses solidify into slabs between 1 and 16-meter (3- to 50-foot) thick. These slabs block water from flowing through, which ends up flowing downhill into the ocean.

Climate warming is also increasing the quantity of meltwater in Greenland. In July of 2012, snow and ice melted from 97% of Greenland’s ice sheet surface, which the team says has never before been seen the 33-year-long satellite record. This spring, which was particularly warm and sunny in Greenland, resulted in a record-setting 80 billion tons of Greenland ice melted.

“As the climate continues to warm, these ice slabs will continue to grow and enhance other meltwater feedbacks,” said Mahsa Moussavi, a coauthor on the paper. “It’s a snowball effect: more melting creates more ice slabs, which create more melting, which creates again more ice slabs.”

All in all, this process will fundamentally alter the ice sheet’s equilibrium. The team warns that we need to understand Arctic feedbacks like this one because they show just how much, and how quickly, a warming climate can change Earth’s most vulnerable regions.

“Humans have a choice about which way this goes,” MacFerrin said.

The paper “Rapid expansion of Greenland’s low-permeability ice slabs” has been published in the journal Nature.


Some seagulls will steal your food unless you stare them in the eyes

If you want to keep your snacks safe at the beach, be ready to stare down bold seagulls.


Image via Pixabay.

Researchers at the University of Exeter report that looking straight at a gull that’s stalking your food can help dissuade the bird from approaching. The team placed a clear plastic bag filled with chips in front of herring gulls and tested how long it took the birds to approach when a human was watching them, compared to when they were looking away.

On average, gulls took 21 seconds longer to make a run for the chips when a human was looking at them.

To unboldly steal snacks

“Gulls are often seen as aggressive and willing to take food from humans, so it was interesting to find that most wouldn’t even come near during our tests,” said lead author Madeleine Goumas, of the Centre for Ecology and Conservation at Exeter’s Penryn Campus in Cornwall.

“Of those that did approach, most took longer when they were being watched. Some wouldn’t even touch the food at all, although others didn’t seem to notice that a human was staring at them.

The team attempted to run the test with 74 herring gulls (Larus argentatus) in coastal towns in Cornwall, but most flew away or would not approach. Only 27 finally made a pass at the chips, and out of these, only 19 tried both when watched by a researcher (the experimental condition) and when the researcher looked away (the test condition). Those 19 gulls make the object of this study — so its sample size is quite small.

Staring at the birds did seem to work, they report. Gulls took longer to approach the food when a human was staring at them, and some didn’t even dare attempt to steal the snacks. However, there was significant variation between individual birds’ behaviors. “We found that only 26% of targeted gulls would touch the food, suggesting that food-snatching is likely to be conducted by a minority of individuals,” the paper reads.

The results show that it’s overkill to treat all gulls as being alike, as most are too wary to come near humans. However, it does pay to stare down those few very bold ones, as that might just be the difference between getting your snack stolen or enjoying it yourself.

“We didn’t examine why individual gulls were so different. It might be because of differences in “personality” and some might have had positive experiences of being fed by humans in the past — but it seems that a couple of very bold gulls might ruin the reputation of the rest,” explains senior author Dr. Neeltje Boogert added.

What Dr. Boogert recommends, especially during beach season when gulls are “looking for an easy meal,” is for people to keep an eye on their surroundings for approaching gulls. They often fly down or come from behind people, snatch up food, and run away — but if you can spot them coming and look directly at them, they might just get cold feet.

“Gulls learn really quickly, so if they manage to get food from humans once, they might look for more,” Dr. Boogert explains.

“It seems that just watching the gulls will reduce the chance of them snatching your food.”

The UK’s herring gulls are in decline, the paper further reports, although their numbers are increasing in urban areas. Gulls’ natural diet consists of fish and invertebrates. Both of which are, understandably, hard to get in the city, so the gulls resort to stealing food from humans quite frequently. In the future, the team wants to investigate how eating human foods affects the gulls, and their chicks, in the long term.

The paper “Herring gulls respond to human gaze direction” has been published in the journal Biology Letters.

Magnetic coils, the new way to deal with microplastics

Flowing through rivers and oceans, plastic waste has become an important environmental threat across the globe. Trying to deal with the problem, researchers in Australia developed a way to purge water sources of microplastic without harming microorganisms, using a set of magnets.

Credit: Flickr


Microplastics are ubiquitous pollutants. Some are too small to be filtered during industrial water treatment, such as exfoliating beads in cosmetics, while others are produced indirectly when larger debris like soda bottles or tires weather amid sun and sand.

“Microplastics adsorb organic and metal contaminants as they travel through water and release these hazardous substances into aquatic organisms when eaten, causing them to accumulate all the way up the food chain,” said senior author Shaobin Wang, a professor at the University of Adelaide (Australia).

Wang and the research team generated short-lived chemicals, called reactive oxygen species, which trigger chain reactions that chop the polimers (long molecules) that makeup microplastics into tiny and harmless segments that dissolve in water. The study was published in the journal Matter.

The problem was reactive oxygen species are often produced using heavy metals such as iron or cobalt, which are dangerous pollutants in their own right and thus unsuitable in an environmental context. To get around this, they used carbon nanotubes laced with nitrogen to help boost the generation of reactive oxygen species.

“Having magnetic nanotubes is particularly exciting because this makes it easy to collect them from real wastewater streams for repeated use in environmental remediation,” says Xiaoguang Duan, a chemical engineering research fellow at Adelaide who also co-led the project.

The carbon nanotube catalysts removed a significant fraction of microplastics in just eight hours while remaining stable themselves in the harsh oxidative conditions needed for microplastics breakdown. Their coiled shape increased stability and maximized reactive surface area. Chemical by-products of this microplastic decomposition, such as aldehydes and carboxylic acids, aren’t major environmental hazards. The team, for example, found that exposing green algae to water containing microplastic by-products for two weeks didn’t harm the algae’s growth.

The next step of the research will be to ensure that the nano springs work on microplastics of different compositions, shapes, and origins, as all microplastics are chemically different. They also think that the byproducts of microplastic decomposition could be harnessed as an energy source for microorganisms.

“If plastic contaminants can be repurposed as food for algae growth, it will be a triumph for using biotechnology to solve environmental problems in ways that are both green and cost-efficient,” Wang says.



Antarctic instability could raise sea levels by half a meter in 150 years

We’re seriously underestimating Antarctica’s ability to push global sea level rise, a new study reports.


Image credits Luis Valiente.

Ice masses in the southern continent are becoming extremely unstable due to climate change, the authors explain, but this isn’t readily apparent. The team behind the study, with members from the Georgia Institute of Technology, NASA Jet Propulsion Laboratory, and the University of Washington, says that this hidden instability will likely accelerate water flow into the ocean and raise sea levels much faster than previously estimated.

Thawing the Antarctic

Five Antarctic glaciers have doubled their rate of ice loss over the last six years, according to the study, with at least one (the Thwaites Glacier) being in danger of collapse. While we can’t accurately estimate exactly how glacier runoff will evolve over the coming 50 to 800 years yet (this is dependant bot on our choices and on unknown factors such as topography), the team have done their best to cover all possible outcomes. For this, they’ve run 500 ice flow simulations for Thwaites’ evolution. While there was a wide range of variation between the scenarios, they all ended in the eventual collapse of Thwaites.

Glacier collapse has a lot to do with the geometry of the bedrock underpinning the ice. Glaciers whose leading edge ‘hangs’ in the ocean instead of being supported by bedrock are called tidewater glaciers. The point at which they glaciers start to float is the grounding line. Glacier instability/collapse first starts here.

Glacier shelf interaction.

Image credits Ted Scambos, Michon Scott / National Snow and Ice Data Center.

Warmer temperatures also heat up the ocean water, which starts eating away at the bottom of the glacier (which raises sea levels). This process also accelerates the rate at which glaciers fragment and float out into the sea. This is perhaps the most worrying process from a sea-level perspective: these bits of ice eventually melt in the wider ocean, but the process also speeds up the rate at which glaciers slide into the waters (as they’re no longer buoyed up by the ocean), leading to more and more melting.

“Once ice is past the grounding line and just over water, it’s contributing to sea level because buoyancy is holding it up more than it was,” says Alex Robel, an assistant professor in Georgia Tech’s School of Earth and Atmospheric Sciences and the study’s lead author. “Ice flows out into the floating ice shelf and melts or breaks off as icebergs.”

The simulations show that even if we do stop climate warming in the future, instability in Thwaites will keep feeding water into the global ocean at extremely fast rates compared to the baseline value. These results are based on present-day ice melt rates, meaning that higher rates of global warming will lead to faster and stronger melt rates than identified in this paper.

Worst of all, if Thwaites does collapse, it will trigger a feedback loop leading to more and more melt as it slides into the ocean at faster rates.

“If you trigger this instability, you don’t need to continue to force the ice sheet by cranking up temperatures. It will keep going by itself, and that’s the worry,” said Robel.  “Climate variations will still be important after that tipping point because they will determine how fast the ice will move.”

“After reaching the tipping point, Thwaites Glacier could lose all of its ice in a period of 150 years. That would make for a sea level rise of about half a meter (1.64 feet),” adds NASA JPL scientist Helene Seroussi, a co-author of the paper. “The process becomes self-perpetuating”.

Currently, sea levels are 20 cm (almost 8 inches) above pre-industrial levels. Sea ice doesn’t raise sea levels as it melts — all that ice is already in the water so it already contributes a volume to the global ocean — but land-borne glaciers do. Antarctica holds the most land-supported ice, so it can have a very sizeable contribution to sea levels.

“There’s almost eight times as much ice in the Antarctic ice sheet as there is in the Greenland ice sheet and 50 times as much as in all the mountain glaciers in the world,” Robel explains.

It’s not yet clear whether Thwaites has reached the tipping point or not, but its outer edge is sinking into the ocean faster than previously recorded. The findings are particularly worrying as the success of current efforts to proof cities and installations against sea level rise are wholly dependent on having accurate predictions. However, the current study shows that our current forecasts aren’t very reliable.

“You want to engineer critical infrastructure to be resistant against the upper bound of potential sea level scenarios a hundred years from now,” Robel said. “It can mean building your water treatment plants and nuclear reactors for the absolute worst-case scenario, which could be two or three feet of sea level rise from Thwaites Glacier alone, so it’s a huge difference.”

Another surprising finding made by the team is that when climate conditions fluctuate strongly, Antarctic ice evens out the effects. Ice flow in such conditions will increase gradually, not wildly, but the instability produced the opposite effect in the simulations.

“The system didn’t damp out the fluctuations, it actually amplified them. It increased the chances of rapid ice loss,” Robel said.

“[Almost total ice loss in Thwaites] could happen in the next 200 to 600 years. It depends on the bedrock topography under the ice, and we don’t know it in great detail yet,” Seroussi said.

The paper “Marine ice sheet instability amplifies and skews uncertainty in projections of future sea-level rise” has been published in the journal Proceedings of the National Academy of Sciences.


Our emissions could melt all the ice in Greenland by the year 3000 — and raise sea levels by 24 ft

Greenland may actually be green by the end of the millennium if greenhouse emissions continue unabated.


Image credits Marcel Prueske.

New research shows that, if greenhouse gas emissions continue on their current trajectory, Greenland could lose 4.5% of its ice by the end of the century, and all of it by the year 3000. That 4.5% loss of ice is equivalent to roughly 13 inches of sea level rise, the team explains.

Actually Green land

“How Greenland will look in the future — in a couple of hundred years or in 1,000 years — whether there will be Greenland, or at least a Greenland similar to today, it’s up to us,” said first author Andy Aschwanden, a research associate professor at the University of Alaska Fairbanks Geophysical Institute.

Greenland houses a lot of ice — around 660,000 square miles of solid ice sheet, which contains around 8% of all the planet’s fresh water. Between 1991 and 2015, melting here has added about 0.02 inches per year to the sea level. Needless to say, we need to know how all that ice is faring and whether there’s any cause for concern. Turns out that there is.

The team used recent topography (landscape) data of Greenland’s terrain today to model how its ice sheets will evolve in the future. This data was recorded by a NASA airborne science campaign (Operation IceBridge) during which aircraft fitted with a full suite of scientific instruments scanned Greenland’s ice sheets recording its surface, the individual layers within, and the shape of the bedrock. On average, Greenland’s ice sheet is 1.6 miles thick, but there was a lot of variation.

A wide range of scenarios concerning ice loss and changes in sea level are possible based on how greenhouse gas concentrations and atmospheric conditions evolve. The team ran 500 simulations for each emission scenario using the Parallel Ice Sheet Model, developed at the Geophysical Institute, to create a picture of how Greenland’s ice would respond to different climate conditions. The model included parameters on ocean and atmospheric conditions as well as ice geometry, flow, and thickness.

Under a business as usual scenario, we could see around 24 feet to global sea level rise by the year 3000 due to melting in Greenland alone — which would put much of San Francisco, Los Angeles, New Orleans and other cities under water. However, if we do manage to slash greenhouse gas emissions significantly, the prospects improve. Reduced emission scenarios showed between 8% to 25% melting of Greenland’s ice, which would lead to approximately 6.5 feet of sea level rise

Projections for both the end of the century and 2200 tell a similar story. A wide range of outcomes are possible, including saving the ice sheet, but it all depends on emission levels, the team explains.

The team explains that modeling ice sheet behavior is tricky because ice loss is primarily driven by the retreat of outlet glaciers. These are the glaciers at the margin of the ice sheets, and they ‘drain’ ice from deeper in the sheets through through-like structures in the bedrock. This study was the first to include these outlet glaciers in its modeling and found that their discharge could contribute as much as 45% of the total mass of ice loss in Greenland by 2200. Outlet glaciers come into contact with water, the team explains, which makes ice melt much faster than air. The more ice that comes into contact with water, the faster the rate of melting — which creates a feedback loop that dramatically affects the ice sheet’s stability.

Previous research lacked data as comprehensive as that recorded by IceBridge, so it couldn’t simulate the ice sheets’ evolution in such detail.

“Ice is in very remote locations,” says Mark Fahnestock, a researcher at the University of Alaska Fairbanks Geophysical Institute and paper co-author. “You can go there and make localized measurements. But the view from space and the view from airborne campaigns, like IceBridge, has just fundamentally transformed our ability to make a model to mimic those changes.”

“What we know from the last two decades of just watching Greenland is not because we were geniuses and figured it out, but because we just saw it happen,” he adds. As for what we will see in the future, “it depends on what we are going to do next.”

The paper “Contribution of the Greenland Ice Sheet to sea level over the next millennium” has been published in the journal Science Advances.

Skinny seals and hungry cod point to trouble in the Baltic Sea

Not all is well in the Baltic Sea, new research suggests — the local food networks are in trouble.

Baltic sea sky.

Image credits Michal Jarmoluk.

The top predators of the area, gray seals and cod, are losing weight, the study reports. This development is linked to the worsening health of the cornerstones of the Baltic’s local food networks: bottom-living crustaceans, isopods, and amphipods.

Sinking food stocks

“It is important that you understand how the food web works when managing a fishery. It is not enough to manage how the fish and fisheries are changing. The availability and quality of food is at least as important,” explains Lena Bergström, researcher at the Department of Aquatic Resources at the Swedish Agricultural University and the study’s corresponding author.

The study, a collaboration between several universities, looked at the health and abundance of key species over the last two decades in the Bothnian Sea and the Baltic Proper. Seal, cod, herring, sprat, isopods, amphipods, and zooplankton all made the object of this study, as they are important players at different levels of the local food webs. These networks are very complex, the team writes, and the same species can be both prey and predator — for example, herrings eat zooplankton and bottom fauna while being hunted by cod and seals in turn.

The authors show that there is a link between the health of cod and seals, the top predators in this ecosystem, and that of bottom-dwelling species, which are the lowest rung on the ladder. Seals are indirectly linked to these bottom-feeders, as they dine on herrings (who in turn dine on the bottom-dwelling species). The worsening health of both cod and seals, the authors explain, is tied to climate change and eutrophication. Eutrophication is an excess of nutrients in a body of water, frequently due to run-off from land, which causes a dense growth of bacteria and algae.

“Oxygen levels in Baltic Sea have reduced since the 1990s, in big part due to eutrophication, creating vast oxygen-free areas. This leads to less living space for the bottom-living prey animals,” says Agnes Karlsson, lead author and researcher at the Department of Ecology, Environment, and Plant Sciences (DEEP) at Stockholm University.

“This has, among other things, led to the fact that the isopods have become fewer and smaller, making them a poorer food choice for cod.”

The team explains that, while the mean weight and fat content of herring in the Bothnian Sea have recently been on the uptick — made possible by an increase in the quantity of bottom-living amphipods — this isn’t an improvement; it’s a recovery. These crustaceans were almost wiped out by a period of extremely heavy rains in the early 2000s which changed the quality of local waters.

“The upturn is relative, because the amphipod in the Bothnian Sea collapsed in the early 2000s and what we now see are signs of a recovery,” Karlsson adds.

“With climate change it is likely that we will see similar extreme events more frequently in the future,” Bergström adds. “If activities that lead to eutrophication are not reduced, oxygen shortage in the Baltic Sea will likely continue, leading to further reductions in the numbers of bottom-living animals. This can have far reaching effects for the economy, with reference to the fish species that are important commercially. To manage a fishery, we must also manage the environment and the food web.”

The paper “Linking consumer physiological status to food-web structure and prey food value in the Baltic Sea” has been published in the journal Ambio.

Tufted puffin.

Massive puffin die-off in the Bering Sea likely due to climate change, study reports

A mass dying of tufted puffins (Fratercula cirrhata) in the Bering Sea is at least partially the result of climate change, a new study reports.

Tufted puffin.

Image credits Gregory “Slobirdr” Smith / Flickr.

A collaborative research effort between members of the Aleut Community of St Paul Island Ecosystem Conservation Office and citizen scientists at the University of Washington’s COASST program reports that the birds seem to have died from starvation. Tufted puffins feed on fish and smaller marine invertebrates, which in turn feed on plankton — stocks of which are declining due to warming climate conditions.

Puff! You’re dead

“This paper is a successful application of citizen science in the real world. Island residents collected high-quality data in real time and provided COASST with a detailed context for their analysis,” explains Lauren Divine, one of the paper’s co-authors.

“Without the positive and mutually beneficial relationship built over years of collaboration, this massive die-off of Tufted Puffins would have gone unreported in the scientific community.”

Tufted puffin colonies in the Bering Sea have experienced a massive die-off that the team attributes, at least in part, to man-made climate change. The team documented a four-month-long dying off of tufted puffins in the region. They further report that the Crested auklet (Aethia cristatella), another species which nests on the St. Paul Island more to the south of the Bering Sea, is also experiencing a similar decline.

Since October of 2016, local community (including tribal communities) members have recovered over 350 ‘severely emaciated’ carcasses of puffins and auklets, a press release of the paper explains. Most of these birds were adults in the process of molting, which the researchers note is a known nutritional stressor of their life cycle.

The timing also hints to the cause of their demise: a reduction in food resources in the area just before the birds entered molt. The team used wind data in the region to model beachings and calculated that between 3,150 and 8,500 birds could have died in the event. Roughly 87% of these deaths represented puffins, they add, in an area where previously, puffins made up less than 1% of the carcasses recovered in the region. Based on the sheer number of recovered carcasses, the team adds, it’s highly likely that the event affected the species throughout its colonies in the Bering Sea.

They suggest that climate-driven shifts in the availability and/or distribution of prey hit the colony at the onset of molt, causing the die-off. Rising sea temperatures are causing substantial shifts in ocean ecosystems the world over, the team explains, shifts that have previously been linked to mass mortality events in marine bird species. The Bering Sea didn’t escape such changes, with increased atmospheric temperatures and declining winter sea ice cover recorded since 2014. Such changes led to declines in key, energy-rich species in the region, and caused others to shift more northward — all of which left puffin colonies in the southern stretches of the sea hard-pressed to find food.

Further climate variability in this region is probable, according to the team, which suggests that this problem will only get worse — for puffins and other species of marine birds. We simply don’t know if these species will be able to adapt to their rapidly-changing environment in time, so we should do our best to monitor their situation, the team concludes.

The paper “Unusual mortality of Tufted puffins (Fratercula cirrhata) in the eastern Bering Sea” has been published in the journal PLOS ONE.

Scuba Diver.

Robots and AI can help us better understand deep sea species, study reports.

Robots and artificial intelligence may be just what we need to meet the denizens of the ocean floor, a new study reports.

Scuba Diver.

Image via Pixabay.

Artificial intelligence (AI) has an important role to play in helping us understand the large variety of species living on the ocean floor, new research from the University of Plymouth reports. Such systems could finally allow marine researchers to push past the efficiency bottleneck created by human users analyzing recordings from the depths of the sea.

Davy Jones’ locker

“Autonomous vehicles are a vital tool for surveying large areas of the seabed deeper than 60m [the depth most divers can reach],” says PhD student Nils Piechaud, lead author on the study. “But we are currently not able to manually analyse more than a fraction of that data.”

“This research shows AI is a promising tool but our AI classifier would still be wrong one out of five times, if it was used to identify animals in our images.”

The new study analyzed the effectiveness of a computer vision (CV) system in taking over the role of humans in analyzing deep-sea images. All in all, the team found, such as system is around 80% accurate in identifying various animals in images of the seabed but can be up to 93% accurate for specific species if enough data is used to train the algorithm. The authors say that such results suggest CV could soon be routinely employed to study marine animals and plants. In such a case, it would lead to a major increase in data availability for conservation research and biodiversity management, they add.

“But we are not at the point of considering it a suitable complete replacement for humans at this stage,” Piechaud notes.

The team used Google’s Tensorflow, an open access library, to teach a (pre-trained) neural network to identify individuals of deep-sea species found in images taken by autonomous underwater vehicles (AUV). One of these AUVs, known as Autosub6000, was deployed back in May 2016 on the north-east side of Rockall Bank, UK, and collected over 150,000 images in a single dive. Around 1,200 of these images were manually analyzed, containing 40,000 individuals of 110 different kinds of animals (morphospecies), most of them only seen a handful of times.

Manual annotation ranged from 50 to 95% on this dataset; however, it was very slow. And, as you guessed from that ‘ranged’ part, it was quite inconsistent across different teams and work intervals. The automated method reached around 80% accuracy, approaching the performance of humans with a clear speed and consistency advantage. The software worked particularly well for certain morphospecies. For example, it correctly identified a type of xenophyophore 93% of the time.

So should we just use it instead of marine biologists? Well, the authors of this present study don’t think that would be a good idea. The study makes a case for automated systems working in tandem with marine biologists, not replacing them. The AIs could greatly enhance the ability of scientists to analyze the data before them.

And combining the ability of high-tech AUVs to survey large areas of the seabed, the fast data-crunching ability of AI, and expertise of marine biologists together could massively speed up the rate of deep-ocean exploration — and with it our wider understanding of marine ecosystems.

“Most of our planet is deep sea, a vast area in which we have equally large knowledge gaps,” says Dr Kerry Howell, Associate Professor in Marine Ecology and Principal Investigator for the Deep Links project.”

“With increasing pressures on the marine environment including climate change, it is imperative that we understand our oceans and the habitats and species found within them. In the age of robotic and autonomous vehicles, big data, and global open research, the development of AI tools with the potential to help speed up our acquisition of knowledge is an exciting and much needed advance.”

The paper “Automated identification of benthic epifauna with computer vision” has been published in the journal Marine Ecology Progress Series.


Sea level change isn’t constant across the East Coast — because of long-past glaciers

A new study explains why different areas along the U.S. East Coast see significantly more sea level change than others.


Image credits Dimitris Vetsikas.

Seas and oceans across the globe are creeping ever so slowly upwards as climate change warms them up and melts glaciers big and small. However, local sea levels aren’t (surprisingly) the same everywhere — and this holds true for the U.S. East Coast as well. A new study published by researchers from the Woods Hole Oceanographic Institution (WHOI) comes to explain why.

Been under a lot of pressure lately

Over the last century, coastal communities near Cape Hatteras (North Carolina) and the Chesapeake Bay (Virginia) have seen about a foot and a half of sea level rise.  New York City and Miami, in contrast, have only seen roughly two-thirds of that rise (i.e. one foot) over the same period. Farther north in Portland, Maine, for example, sea levels only rose only about half a foot.

Which is weird, right? I mean, all the Earth’s oceans are linked together so, their water should be level, right? Not if you’re on a period of post-glacial rebound, says lead author Chris Piecuch.

Vast areas of land in the Northern Hemisphere, including Canada and parts of the Northeast U.S, were covered in massive glaciers during the last Ice Age, he explains. This effectively squashed the lands, pushing them down into the mantle (the crust is essentially a jigsaw puzzle of solid pieces floating on molten rock — see here). These ice sheets peaked in size and mass during the Last Glacial Maximum some 26,500 years ago, and then started melting to the state we see today. As they did so, the pressure they exerted on the ground also disappeared — and these areas started to rebound. Neighboring lands, meanwhile, started sinking, creating sort of a seesaw effect.

That effect continues to this day, Piecuch explains.

For the study, Piecuch and his team gathered tidal gauge measurements of sea levels in areas such as Norfolk Naval Station in Virginia and the Outer Banks in North Carolina. They also drew on GPS satellite data to see how much local landmasses had moved up and down over time, and looked to fossils recovered from salt marshes (which are a good indicator of past coastal sea levels). They combined all of this observational data with complex geophysical models to produce a more complete view of sea level changes since 1900 than ever before.

Post-glacial rebound, they found, accounted for most of the variation in sea level rise along the East Coast. Interestingly, however, when that factor was removed from the dataset, the team found that “sea level trends increased steadily from Maine all the way down to Florida.”

“The cause for that could involve more recent melting of glaciers and ice sheets, groundwater extraction and damming over the last century,” Piecuch says. “Those effects move ice and water mass around at Earth’s surface, and can impact the planet’s crust, gravity field and sea level.”

“Post-glacial rebound is definitely the most important process causing spatial differences in sea level rise on the U.S. East Coast over the last century. And since that process plays out over millennia, we’re confident projecting its influence centuries into the future. But regarding the mass redistribution piece of the puzzle, we’re less certain how that’s going to evolve into the future, which makes it much more difficult to predict sea level rise and its impact on coastal communities.”

The paper “Origin of spatial variation in US East Coast sea-level trends during 1900–2017” has been published in the journal Nature.