Nature's Black Boxes

By Claire Eamer

Whenever an airplane crashes, you hear about investigators retrieving the plane's black box. It's a device that records essential information about the plane's operation, and it can help investigators reconstruct what happened to bring the plane down.

Tree rings show a tree's history. Claire Eamer photo

Well, there are black boxes in nature too -- lots of them. And they are important tools for scientists who are trying to figure out how Earth's climate changes and what impact those changes have had on the organisms that live on the planet. They're called climate proxies -- essentially indirect clues that let us deduce what past climates were like.

One of the best known black boxes is tree rings. Each year, a tree puts on a ring of new growth. In a good year, the growth ring will be wider, in a bad year, narrower. The science of studying what tree rings can tell us is called dendrochronology, and it has provided a huge amount of information about both natural and human history.

Trees aren't the only organisms that save information in rings. So do fish -- but their growth rings are in their ears. Tiny, disc-shaped bones in fishes' ears -- called otoliths or ear stones[PDF] -- add a ring of growth for every year of a fish's life. As with tree rings, the otolith rings vary, depending on the conditions the fish encountered that year. Even the chemistry of the annual rings changes, so they can hold information about the water the fish traveled through.

The annuli are visible as ridges on this ram's horns.
Pixabay photo

Mountain sheep have a slightly different kind of black box. The rams' horns grow longer and thicker each year, and the ridges that mark each year's growth are called annuli. Like tree rings and otolith rings, the annuli are larger or smaller depending on the conditions the animal experienced that year. In the Yukon, a long-term study of the horns of thinhorn sheep [PDF] revealed a climate fluctuation that repeats every 10 or 11 years and affects the larger ecosystem in which they live.

The biggest natural black box of all is Earth's ice. The great icefields in places like Greenland and Antarctica have been frozen for hundreds of thousands of years -- or even longer. But that ice didn't arrive all at once. It built up year by year with layers of snow that fell and then were compressed into ice by the layers that followed. Digging straight down into a massive icefield is like digging into the past.

Greenland glaciers like this one contain ice more than 100,000 years old.
Pixabay photo.

And that's what icefield scientists do. They drill into glaciers and icefields and extract long cores of ice. Then they analyze the thin layers, examining the chemistry of the water and bubbles of trapped air, the dust and pollen that settled on the glacier's surface, and anything else that might be frozen in the ice. The oldest ice found so far came from Antarctica and is an amazing 2.7 million years old. Ice cores are among the most powerful climate proxies we have, and much of our knowledge of very ancient climates comes from them.

For more information about dendrochronology, explore the EnvironmentalScience.org website.

For some of the things we can learn from fish otoliths, watch the short video on this page.

For a detailed explanation of ice core science, browse through Ice Core Basics.

And for more on climate proxies, try this NOAA site or this page on Palaeoclimatology.

Investigating Ocean Currents in a Rotating Swimming Pool

By Mirjam Glessmer

Have you ever wondered what happens when you put a 13-m-diameter swimming pool on a merry-go-round? Probably not. But I am here to tell you today about what happens when you do just that, and what you can learn from doing so.

I am part of an international group of scientists, doing research on currents in the ocean (and you can read more about who we are and what you do on our blog: http://skolelab.uib.no/blogg/darelius). Specifically, we are interested in how warm water is transported towards an Antarctic ice shelf. As you can imagine, Antarctica is not the easiest place to travel to and measure the ocean, especially not during winter. There are some observations of warm water reaching the ice shelf and contributing to melting the ice, but it is not known yet under what conditions this happens.

Why a pool?

In order to understand how water behaves in the ocean, we are reproducing real-world features that we suspect have an important influence on the current's behaviour, but in miniature, and inside our water-filled tank. Then we can modify those features and observe which parts of them actually determine how the water flows, and which parts are not as important. In our case, we are changing the miniature coastline of Antarctica to see what makes the current turn and flow into a canyon instead of just going straight ahead.

Why rotation?

We need to rotate the tank to represent the Earth's rotation. This is because the Earth's rotation influences all large-scale movements on Earth, including ocean currents: Moving objects get deflected to their left on the Southern Hemisphere. Below is a short video of the rotating, empty tank, to show you what happens when you roll a ball in the rotating tank: It does not go straight ahead but just curves to the side!

Coriolis from Mirjam Glessmer on Vimeo.

Before Nadine, the scientist shown in the video, climbed into the tank, you saw her walking alongside it. Even though the tank was turning very slowly (only one rotation per 50 seconds), she had to walk quite fast to keep up! This is how fast we need to spin the tank in order to have it rotate at the right speed for the size of our Antarctica.

How does it all work?

There is only one tank of this size -- 13 meter diameter! -- in the world, and it is situated in Grenoble, France. Researchers from all over the world travel to France to do their experiments in this tank for a couple of weeks each. In the gif below, you see the tank rotating: First, you see an office moving past you (yes, there are several floors above the water, including the first one with an office, computers, desks, chairs and all! That's where we are during experiments, rotating with the tank) and then you can see the water below, lit in bright green. 

There is a huge amount of effort and money going into running research facilities like this, and everybody working with the tank needs to be highly specialized in their training.

What do experiments look like?

When there is water in the tank, we need some special tricks to show how the water is actually moving inside the tank. This is done by seeding particles, tiny plastic beads, into the water and lighting them with a laser. Then special cameras take pictures of the particles and using complicated calculations, we can figure out exactly how the currents are moving. Below, you see a gif of one of our experiments: The current starts coming in from the right side of the image, flowing along our model Antarctica, and then some of it turns into the canyon, while most of it just goes straight ahead.

Depending on the shape of our Antarctica, sometimes all the water turns into the canyon, or sometimes all of it goes straight ahead.

What have we learned?

That's a difficult question! We are still in the middle of doing our experiments, and the tricky part with research is that doing the experiments (even though that can be a huge undertaking as you see when you look at what a huge structure our tank is, or what enormous effort it requires to go to Antarctica with a research ship) is only a tiny step in the whole process. Nadine, who you saw in the movie above, is one of several people who will work on the data we are currently gathering for the next four years! But even though we are not finished with our research, there are definitely things we have learned. For example, the length of Antarctica's coast line that the current flows along before the canyon interrupts its flow is very important: The shorter it is, the larger the part of the current that turns into the canyon. How all our individual observations will fit together in a larger picture, however, will still take months and years of work to figure out.

Where can I learn more about this?

If you have any questions, we would love to hear from you! We are hosting an "Ask Me Anything" event on October 18th but you can also leave questions on our Facebook page or directly on our blog.

Science in Art

Spoiler warning: this post mentions artistic items people are making for sale -- but they're all about science!

This summer I have run into a few people who are inspired by science to make beautiful things. One is a potter looking at living cells through a microscope. One is a graduate student studying Earth Sciences, who inspires kids learning how science and art overlap in this way. And the third is making large pictures showing melting glaciers -- more colourful than you'd think!

Here's a photo I took this summer at the farmer's market in Sooke, BC, where Sydnie Nicole sells her ceramic art. She's studying Art Education, and the surfaces and glazes of her pottery show designs based on the images she sees of living cells through a microscope. Check out her website at this link, where you can see see photos of her work, and her artist's statement which reads in part:

Carved and stamped by hand, Sydnie’s functional and sculptural work reveals a dedication to detail that bridges the disciplines of craft and science into the everyday world.

One particularly charming oval platter is designed to show what a pine needle looks like when you cut a slice across the needle and focus a microscope on the slice. Along with mugs and bowls and plates she makes from clay, Sydnie also has this interesting panel of wall art you can see on the easel behind her, called "Biomedical Artistica." She teamed up with biomedical grad researcher Andrew Agbay for this piece, which shows small spheres delivering medication to the network of living stem cells turning into neurons.

This pair of pottery pieces is a particular favourite of hers -- it's salt and pepper shakers, that sit on her dining table. The nifty part is that the salt cellar is shaped like salt crystals are, in a cube. The pepper shaker is shaped like a black peppercorn, round with wrinkles. Charming!

I found another science artist, but this time online. Jill Pelto is studying for her Masters degree in Earth Sciences at University of Maine. You can check out her Twitter feed at this link, which shows some of her interesting drawings. "I create field sketches of places I have researched, and environmental illustrations," wrote Jill Pelto on her Twitter profile. Y'see, Jill not only makes drawings in the field when she's out gathering data on glaciers and doing research in places as far away as the Falkland Islands, or New Zealand and Antarctica. She makes art based on the jagged lines and curves made when her data is printed in a graph. Sometimes a zigzag line will look to her like a melting glacier, other times it will be part of her drawing of a forest fire. 

Here is an image of her work "Proxies for the Past" which appeared on Yale Climate Connections website. You can read what they wrote about Jill Pelto and her art at this link. To see more of Jill Pelto's art, check out this link to where she sells some of her Glaciogenic Art, including that image.

 

On Twitter, there's a link to images created by students who were inspired by Jill Pelto's art. It's nice to see emerging art as well as her polished pieces.

And if you're a fan of science-inspired art and want to see more, check out the pastel drawings done by Zaria Forman at this link, where she is making a striking series of images based on photographs of glaciers in Antarctica. She makes drawings and paintings using pastels, a chalk-y medium, on large sheets of white paper and large canvases. In the video shown at the link, she is working on a drawing big enough that she is using her fingers to apply the pastels. Melting glaciers means more than just statistics to me when I can see so many shades of blue and white in the ice she draws!

Penguin Enthusiasm

No, I'm not a penguin scientist -- though I am applying to join an Antarctic expedition as a writer-in-residence. But I did enjoy finding this pair of photos of a penguin who appears to be trying to join an expedition of his own:

Hair Ice and Singing Lakes and Icebergs: Fabulous Ice Phenomena

Jan Thornhill

Hair ice growing from twig.

Antarctic sea ice (NASA)

My friend Ulli called one chilly morning a couple of weeks ago and said she’d found a stick in the woods for me. “A stick?” I said.

“You want it,” she said cryptically.

She was right. Though what she brought over ten minutes later looked like an ordinary piece of a dead alder branch, part of it was not ordinary in the least. One end had sprouted a glorious tuft of long silky white hair. Ulli had found hair ice!

Hair ice starting to melt. (Jan Thornhill)

Though you might think at first glance that hair ice is some kind of peculiar frost – it’s not. Frost forms when moisture in the air freezes on objects. Hair ice, on the other hand, starts from the inside and moves outwards. Moisture in a stick or twig is exuded through minute pores on the surface, and when this moisture hits humid sub-zero air the result is very fine filaments of ice that can grow up to five centimeters in length – filaments that look just like hair. It’s an uncommon phenomenon, and not just because weather conditions must be absolutely perfect. Here's the real glitch: the appearance of hair ice seems to be dependent on, of all things, fungi.

Hair Ice and Fungi

So what do fungi have to do with it? The idea that “a fungus participates in a decisive way” in the formation of hair ice, was first suggested in 1918 by the brilliant interdisciplinary scientist Alfred Wegener (who developed the theory of continental drift), but was unproven. Recently though, Gerhart Wagner and Christian Mätzler from the University of Bern have been studying "haareis" and its relationship to fungi. In one experiment they collected a number of twigs that had previously grown hair ice and treated them variously with three agents known to suppress the growth of fungi – heat, alcohol, and fungicide – while keeping a portion of each twig aside as a control. Afterwards, they froze all the samples under identical conditions, then compared the results. Sure enough, only the untreated pieces re-grew luxuriant manes of ice. 

The two scientists theorize that the living mycelium of various fungi within the wood (i.e. Exidia glandulosa or Tremella mesenterica) continues to metabolize at near freezing temperatures, producing heat and gases that force moisture outwards. When this moisture escapes through pores and comes into contact with humid below-freezing air, hair ice grows.

Hair ice that grew overnight. (Jan Thornhill)

After reading about Wagner and Måtzler's success at coaxing hair ice to grow in the laboratory, I decided to try to try a simple experiment of my own. I soaked the stick Ulli had brought me in water (its original hair ice having quickly melted). I then laid it on a wet paper towel on a plate and put it out in our unheated boot room, then waited for the temperature to drop. By the 10:00 pm the whole stick was sprouting hair ice. By morning I had a new pet!

The end of the twig  formed solid globules of ice, possibly
because moisture was released too quickly to form hair ice. (Jan Thornhill) 

Singing Lakes

A few days later, another friend was talking about how much he loves the quality of the human voice outside on cold winter days. The topic of walking on frozen lakes came up. I asked if he’d ever heard a frozen lake “sing.”

Frozen lakes sing! (Nentori)

I’ve heard it several times – haunting, otherworldly sounds caused by ice expanding and contracting, which is most common when there are major fluctuations in temperature. The best sounds, and the ones that carry the furthest, occur when there is no snow cover – rare conditions on the lakes near where I live, but not unheard of. Listen to Andreas Bick’s extraordinary recording of this phenomenon on a lake in Germany here. Turn up the volume and brace yourself!

Antarctic Ice & Animal Sounds

Weddell seals whistle and chirp.

And then I discovered something even more wonderful: The Alfred Wegener Institute (yes! that's the same Alfred Wegener as mentioned above!) that co-ordinates German polar research in both the Arctic and Antarctic has an acoustic laboratory in Antarctica. They are always recording – and on their website they offer this MP3 audio livestream of Antarctic ice and animal sounds from near the Neumayer Station on the ice shelf of Atka Bay. You can listen to the under-ice sounds of the Antarctic in real time! I can't turn it off!

All of this icy stuff is so cool it warms my heart. 

More Links:

This page from the Alfred Wegener Institute has sound files of various seal and whale noises to listen for on the live audio feed, as well as rubbing ice, singing icebergs, and some “mystery” sounds that are truly astonishing.

Download Gerhart Wagner and Christian Mätzler"s paper,  "Haareis auf morschem Laubholz als biophysickalisches Phanomen"  or  "Hair Ice of Rotten Wood of Broadleaf Trees – A Biophysical Phenomenon" – lots of pictures, though only some parts are in English.




Weddell seals source: http://commons.wikimedia.org/wiki/File:Diving_weddell_seals.jpg