Tag Archives: Jonathan Amos

Antarctic Hotspot Under the Ice

As the ice melts all over the Earth, particular attention centers on Antarctica.  If and when the Southern ice cap melts, the oceans will rise by tens of meters, drowning much of where humans live.  When will this happen, if ever?  We need to know.

Antarctica is a continent, and that means it is big and complicated. Some places are melting fast.  Others aren’t changing much, and some may actually be accumulating more ice.

One of the unknowns is what is under the ice.  We can easily see the top of the snow and ice (at least some of the time.)  But what is going on in the kilometers deep ice, and what is at the bottom?

The is actually a critical question for several reasons.  Ice that is resting on dry, cold, rock will be solidly anchored and will generally melt only where exposed to air and ocean.  But ice resting on water will melt and slide downhill, generally ending up in the ocean, where it will melt.  And ice resting on warm rock will melt from below.

In Greenland, there are areas where volcanic heat under the ice is thinning and weakening the ice, and speeding the rate of melting.

This fall, researchers from Europe report on studies using airborne ice penetrating radar near the South Pole [2].  The study identifies an area that is a geothermal hot spot under the ice, where the overlying 2+ km deep ice cap is sagging.

The saggy spot is approximately 100 x 50 km, and the sag is consistent with melting of about 6 mm per year.  This seems to be much more than would be expected from the rocks, so the researchers suggest that there is geothermal flows of hot water from deeper rocks.

This finding is important for numerical models of the ice, which generally use a uniform, lower estimate of the heat of the rocks.  This hot spot, and other similar anomalies could have substantial effects on the changes to the ice cap.

The study is also interesting because it uses ice penetrating radar to create a three dimensional view of the ice, from which they discover the ‘sag’ and inferred the estimated rate melting.  The result gives a way to estimate the heating under the ice, even where no direct measures are available.  (And direct measures of the rock under the ice cap are very difficult to obtain.)

And, as noted, in this case the estimate is much higher—more than twice as high—as previous estimates.  It is noted that these results may explain the presence of numerous subglacial lakes in that area.

The details of the techniques are beyond my own paltry understanding of either ice or radar. Given the complex dynamics of the ice cap, there will need to be additional studies and cross validation to make sure these estimates are accurate.

These results will also guide ongoing plans to sample the ancient ice from this area.  It is thought that this area has some of the oldest ice on the planet, and examination of embedded air bubbles would reveal a history of climate far into the past.  However, the ice in this warm, sagging zone will have remelted and would not retain the ancient bubbles.  So the search for records of the climate should avoid these areas [1].


  1. Jonathan Amos, South Pole: Rock ‘hotspot’ causes ice sheet to sag, in BBC News – Science & Environment. 2018.  https://www.bbc.com/news/science-environment-46202255
  2. T. A. Jordan, C. Martin, F. Ferraccioli, K. Matsuoka, H. Corr, R. Forsberg, A. Olesen, and M. Siegert, Anomalously high geothermal flux near the South Pole. Scientific Reports, 8 (1):16785, 2018/11/14 2018. https://doi.org/10.1038/s41598-018-35182-0

 

Observing Whales From Space

I love whales, though I rarely get to see any out here in the corn fields.

The giant cattle of the sea are seriously threatened by the multiple effects of swarming humans, so it is important to learn as much as possible about them.  But it isn’t easy to observe and track individual animals in the wide blue ocean, so we have little solid information about how many whales live where.

Researchers at the British Antarctic Survey report this fall studies that demonstrate the ability to track individual whales from satellite imagery [2].

The technique uses imagery from the Worldview-3 satellite, which can deliver images of the ocean with sub-meter resolution.  At this resolution, it is possible to discern whales swimming on or near the surface with enough detail to understand some of the behavior of the whale. For example, at this resolution a whale’s fluke occupies 6-10 pixels—which opens the possibility of identifying individual whales in satellite images.

At a resolution of 31cm, species identification becomes much easier. (From [1])
The study developed automated recognition algorithms to pick out four species of whales and ignore boats and small aircraft.  The study manually identified whales and non-whales in sample images.  The study found that spectral features from the image could be used to automatically identify whales, and distinguish them from non-whales.

The paper notes that whales are easier to detect when swimming parallel to the surface, but much harder to identify in other behaviors.  They also note that the coloration of different species makes them easier or harder to detect in the water.

This work could lead to automated an automated scanning system, perhaps coupled with crowd sourced human scanning.

The research plans to follow up with a detailed survey of the Ligurian Sea protected area [1].

I have to be a little worried about this research.  If researchers can do this, then anyone can.  (Note that this uses purchased commercial imagery that is available to anyone.) The last thing our cetacean friends need is for hunting ships to have real time tracking satellite data.


  1. Jonathan Amos, Scientists count whales from space, in BBC News – Science & Environment. 2018. https://www.bbc.com/news/science-environment-46046264
  2. Hannah C. Cubaynes, Peter T. Fretwell, Connor Bamford, Laura Gerrish, and Jennifer A. Jackson, Whales from space: Four mysticete species described using new VHR satellite imagery. Marine Mammal Science, 0 (0) 2018. https://doi.org/10.1111/mms.12544

The Polar Plantscape Is Changing Rapidly

As the Anthropocene climate changes accelerate, we are seeing life forms (with the exception of humans) responding to the changing conditions.  Animals are moving uphill and northward, following the warming trends.

At the same time, plants are “migrating” and adapting.  Oak trees and other species are “moving” north, inhabiting areas that were previously too cold, and dying out in over heated southern ranges.

Even in polar regions, the inhabitants are adapting to the melting ice and warming air.  Penguins seem to be shifting nesting grounds, presumably following changing conditions.

This fall two studies report on how the plant (or at least non-animal) life is “moving” in the Arctic and Antarctic.


Until recently, some areas of Antarctica had large areas of moss that was covered by snow and ice in the winter.  In the summer, the cover melted these beds were exposed to the sun.  In this very wet, very sunny situation, the moss greened and thrived.  In fact, the beds seem to have persisted in the same location for years, probably centuries.

These are the “miniature old growth forests” of East Antarctica.  They are also home to many (small) animals and other species such as fungus.

A new report shows that some of these beds are rapidly dying out, apparently because the climate is drying out [4].  (Growing moss is all about water.)  Other more tolerant mosses are invading the area.

Tiny as they are, this rapid change to the “moss forest” is a huge ecological shift.

At the same time, another study reports that in northern regions tundra plants such as grasses have grown taller, and larger species are moving north [2].  In fact, getting on twice as tall.  There are no trees in these harsh locations, so these ankle high species are the “miniature old growth forests” of the tundra.  And they are bulking up in response to warmer, wetter conditions.

compare it to the ecosystems around your house like the forest nearby – if you imagined that forest getting twice as tall; that is a pretty dramatic change,” (Isla Myers-Smith, quoted in [1])

The presence of these taller plants might create a positive feedback, insulating the soil (e.g., by trapping blowing snow) and lowering the albedo (due to foliage sticking above the snow).  These effects could contribute to more melting of ice and permafrost, further warming the area.


Not only are the old growth forests shrinking and dying, these “miniature” old growths, mosses and grasses and such, are also changing rapidly.

It’s kind of a cool image, “miniature old growth forests”.


(For the record, the data is available from “Team Tundra” and the Austrailian Antarctic Data Center (AADC) )


  1. Jonathan Amos, Taller plants moving into warmer Arctic, in BBC News – Science & Environment. 2018. https://www.bbc.com/news/science-environment-45652152
  2. Anne D. Bjorkman, Isla H. Myers-Smith, Sarah C. Elmendorf, Signe Normand, Nadja Rüger, Pieter S. A. Beck, Anne Blach-Overgaard, Daan Blok, J. Hans C. Cornelissen, Bruce C. Forbes, Damien Georges, Scott J. Goetz, Kevin C. Guay, Gregory H. R. Henry, Janneke HilleRisLambers, Robert D. Hollister, Dirk N. Karger, Jens Kattge, Peter Manning, Janet S. Prevéy, Christian Rixen, Gabriela Schaepman-Strub, Haydn J. D. Thomas, Mark Vellend, Martin Wilmking, Sonja Wipf, Michele Carbognani, Luise Hermanutz, Esther Lévesque, Ulf Molau, Alessandro Petraglia, Nadejda A. Soudzilovskaia, Marko J. Spasojevic, Marcello Tomaselli, Tage Vowles, Juha M. Alatalo, Heather D. Alexander, Alba Anadon-Rosell, Sandra Angers-Blondin, Mariska te Beest, Logan Berner, Robert G. Björk, Agata Buchwal, Allan Buras, Katherine Christie, Elisabeth J. Cooper, Stefan Dullinger, Bo Elberling, Anu Eskelinen, Esther R. Frei, Oriol Grau, Paul Grogan, Martin Hallinger, Karen A. Harper, Monique M. P. D. Heijmans, James Hudson, Karl Hülber, Maitane Iturrate-Garcia, Colleen M. Iversen, Francesca Jaroszynska, Jill F. Johnstone, Rasmus Halfdan Jørgensen, Elina Kaarlejärvi, Rebecca Klady, Sara Kuleza, Aino Kulonen, Laurent J. Lamarque, Trevor Lantz, Chelsea J. Little, James D. M. Speed, Anders Michelsen, Ann Milbau, Jacob Nabe-Nielsen, Sigrid Schøler Nielsen, Josep M. Ninot, Steven F. Oberbauer, Johan Olofsson, Vladimir G. Onipchenko, Sabine B. Rumpf, Philipp Semenchuk, Rohan Shetti, Laura Siegwart Collier, Lorna E. Street, Katharine N. Suding, Ken D. Tape, Andrew Trant, Urs A. Treier, Jean-Pierre Tremblay, Maxime Tremblay, Susanna Venn, Stef Weijers, Tara Zamin, Noémie Boulanger-Lapointe, William A. Gould, David S. Hik, Annika Hofgaard, Ingibjörg S. Jónsdóttir, Janet Jorgenson, Julia Klein, Borgthor Magnusson, Craig Tweedie, Philip A. Wookey, Michael Bahn, Benjamin Blonder, Peter M. van Bodegom, Benjamin Bond-Lamberty, Giandiego Campetella, Bruno E. L. Cerabolini, F. Stuart Chapin, William K. Cornwell, Joseph Craine, Matteo Dainese, Franciska T. de Vries, Sandra Díaz, Brian J. Enquist, Walton Green, Ruben Milla, Ülo Niinemets, Yusuke Onoda, Jenny C. Ordoñez, Wim A. Ozinga, Josep Penuelas, Hendrik Poorter, Peter Poschlod, Peter B. Reich, Brody Sandel, Brandon Schamp, Serge Sheremetev and Evan Weiher, Plant functional trait change across a warming tundra biome. Nature, 562 (7725):57-62, 2018/10/01 2018. https://doi.org/10.1038/s41586-018-0563-7
  3. Victoria Gill, Climate change kills Antarctica’s ancient moss beds, in BBC News – Science & Environment. 2018. https://www.bbc.com/news/science-environment-45629395
  4. Sharon A. Robinson, Diana H. King, Jessica Bramley-Alves, Melinda J. Waterman, Michael B. Ashcroft, Jane Wasley, Johanna D. Turnbull, Rebecca E. Miller, Ellen Ryan-Colton, Taylor Benny, Kathryn Mullany, Laurence J. Clarke, Linda A. Barry, and Quan Hua, Rapid change in East Antarctic terrestrial vegetation in response to regional drying. Nature Climate Change, 8 (10):879-884, 2018/10/01 2018. https://doi.org/10.1038/s41558-018-0280-0

 

ICESat2 Launches – its Space Lasers, man!

One of the most pressing scientific questions is “what is happening to the ice?”  There is abundant evidence that much of the Earth’s ice is melting, and melting at a rate not seen for a long time.

But this is not a simple process, the ice is not melting everywhere ,at least not at the same speed.  In particular, some parts of Antarctica seem to be thinning, while others are not.  And the ice is moving, and ending up in the ocean, which affects the rate of melting.

We really need to know what’s going on. If and when the Antarctic ice melts, all of human civilization will be flooded—among other exciting implications.

Measuring ice is difficult, especially measuring whole continents worth of ice cover. <<link>>  To do it well, it is necessary to combine information from multiple sources, measurements from ground, air and space.

Satellite observation has the advantage that it can cover vast areas, though in less detail. In the last decades several satellites have measured the height of the ice with radar, aiming to estimate how thick the ice is.  This is a tricky inference, because the height of the ice may be affected by other factors, including fresh snow.

This fall, NASA has launched a new satellite that will add new measurements that, combined with radar altimetry and other data, will give a better estimate of ice thickness.  The ICESat-2  uses space lasers, bright green space lasers.

Green lasers. From space.  Dude!  Its so trippy!

The method is simplicity itself.  Zap a bunch of green photons, pick up the one in a million that bounces straight back, and record its time of flight.  Piece of cake. (Not.)  This information should be able to give a measure of the height of the ice where the photon hit to better than a centimeter accuracy (!), measuring every meter or so.  With repeat measurements every 90 days, it will be possible to build up a history of the seasonal and ongoing changes.

According to the web, the instrument will also be useful on cloudy days, providing data for studies of weather and storms.  It also can measure sea and land in the rest of the world.

 

This data is specifically designed to combine with existing radar data. As Jonathan Amos explains, the laser reflects off the top of the snow, while the microwave radar penetrates deeper into the snow [1].  Combining the two will make it possible to understand the snow-covered-ice situation more clearly, and get a better estimate of the thickness of the ice.

Cool!


  1. Jonathan Amos, ICESat: Space will get unprecedented view of Earth’s ice, in BBC News – Science & Environment. 2018. https://www.bbc.co.uk/news/science-environment-45523524

Iceberg finally moving north

We’ve been watching the huge chunk of the Larsen ice shelf in Antarctica which rapidly broke free. Renamed iceberg A-68, it is recorded as the sixth largest iceberg ever.  She’s a big girl.

A berg this large takes a lot to get moving, so it has not moved far—until recently.

As BBC puts it, “The monster Antarctic iceberg A-68 looks finally to be on the move.”  It is pivoting and moving out to sea. This movement probably gouged out the sea bottom as she struggled free.  Expeditions are on the way to examine the area.

https://www.bbc.co.uk/news/av/embed/p06kbhq0/45421315

The berg will drift north, melting and breaking up. Remnants will probably still be seen for a year or more.


  1. Jonathan Amos, Monster iceberg’s pivot and turn, in BBC News – Science & Environment. 2018. https://www.bbc.co.uk/news/science-environment-45421315

 

Where is the Larsen C iceberg now?

Last year there was great interest as a huge piece of the Larsen C Ice Shelf off Antarctica “suddenly” broke off and became a huge floating iceberg the size of Delaware.  (The separation happened over months—which is extraordinarily fast for continental scale processes….)

From the rapid break, we were all prepared for the new berg, tagged A-68, to cruise North, ravaging the sea lanes, frightening penguins, menacing villages, and generally raising havoc.

Iceberg attacks Innaarsuit Greenland ( Credit Reuters) This is not A-68–yet.

So what has happened since?

As BBC reports, A-68 has not moved far, nor has it melted [1].

She’s a pretty big girl, and it takes a while to get a trillion tonnes of ice up to much speed.  In addition, there are winds and tides pushing in many directions and the sea floor is shallow and not necessarily flat that near shore.

Time-series of Sentinel-1 satellite radar imagery showing the rift, calving, and subsequent journey of Iceberg A-68 (From [2]
But models indicate that eventually old ’68 will reach the Atlantic and start moving with the currents. A-68 will sail north, past the equator into the North Atlantic, probably shedding lots of smaller bergs as she breaks up in the heat.

Equally interesting is what will happen to the ice she left behind.  The departure of such a large hunk presumably makes way for more ice to shift and break off into the sea.  The question remains whether A-68 is part of an accelerated breakup of the sea and shore ice at that part of Antarctica.  The situation is being carefully monitored. [2]


  1. Jonathan Amos, The ‘monster’ iceberg: What happened next?, in BBC News – Science & Environment. 2018. https://www.bbc.com/news/science-environment-44745734
  2. Adrian Luckman, Martin O’Leary, and Project MIDAS, Iceberg A68 one year on, in MIDAS blog. 2018. http://www.projectmidas.org/blog/A-68-Anniversary/

 

Big Expedition to Antarctic Glacier

At the same time that the bees are disappearing and dying out, the ice is melting—everywhere.

In recent years, there have been a number of careful studies using remote sensing data and computational simulations of ice in Greenland and Antarctica.  These studies show that Greenland is melting everywhere at an accelerating pace.  This trend has been confirmed by close up, in situ, studies of the ice and sea.

The studies of Antarctica show a more complex picture, with some areas experiencing rapid retreat of glaciers, and other areas apparently holding steady.  There have been relatively few in situ studies—Antarctica is a huge space, very far away, and very hard to visit.

This spring the US National Science Foundation and UK Natural Environment Research Council announced a joint expedition to intensely study the Thwaites Glacier in Antarctica.   The International Thwaites Glacier Collaboration (ITGC) will include measurements of the surface and interior of the ice, the ocean, and the local atmosphere.

Thwaites Glacier has been observed from space to be changing rapidly, shedding ice into the ocean, and apparently thinning.

This expedition will flesh out a much more detailed picture of what is really happening, and possibly better predictions of the future of this ice.

The BBC indicates that if this rapid change leads to a complete collapse, the melt water from Thwaites would raise the average sea level by 80cm—knee deep.  It would be nice to know if such a collapse is immanent, no?

The research activity will include a variety of studies including drilling (to study the history of the ice, rock, and sediments), measurements of the ocean (including deployment of the submersible Boaty McBoatface and sensors attached to marine species), and radar and other sensors.  Cool!

One of the key questions remains the interaction of the relatively warm ocean and the ice.  Studies have shown that in some cases the ocean is invading farther under the ice, changing the grounding line.  The expedition will collect close up measurements of the glacier, to determine what is happening under the ice.

I don’t know if this actually is the “Biggest ever Antarctic field campaign”, but it is certainly a major effort, and the biggest in recent decades.

It will be interesting to see the results from these studies in the coming years.


  1. Jonathan Amos, Thwaites Glacier: Biggest ever Antarctic field campaign, in BBC News – Science & Environment. 2018. http://www.bbc.com/news/science-environment-43936372
  2. National Science Foundation, US and UK join forces to understand how quickly a massive Antarctic glacier could collapse, in NSF News Release. 2018. https://www.nsf.gov/news/news_summ.jsp?cntn_id=245261