Clear ice in January, 2013: Ice thick enough to support a person’s weight, but clear enough to see through. Creating this beautiful shock pattern took a lot of time and concerted effort.
In January, the creek froze over after a few days of below zero (Celcius) temperatures. However, we’d missed the snow that usually accompanies a drop in temperature (it had hit to the south of us), so the ice froze clear and firm. Since they’re used to seeing the whiter ice — on lakes and ice rinks, for example — my students wondered why the ice was so clear.
In February, we got both the snow and cold, which incorporated air bubbles into the ice, resulting in a very different, cloudier ice.
Snow incorporated into the ice makes it cloudier and, I think, somewhat ethereal. Note the same fallen walnut tree trunk as in the picture above.
It was quite neat to see the contrast, and made me wonder about the ecological impact. After all, clear ice lets sunlight through much more efficiently than cloudy ice.
While not quite as dramatic as drilling through four kilometers of ice to find signs of live in an Antarctic lake that’s been isolated from the rest of the world for over 100,000 years, we observed filamentous algae blooming under the clear ice on the creek earlier this winter.
Algae under the microscope (40x magnification).
I collected some of the algae and put it into the fish tank; I was hoping I could use it when we looked at plant cells because aquatic plants tend to have larger cells that are easier to see under the microscope.
However, one of my students is keeping tadpoles (also from the creek) in the fish tank. She noticed that the tadpoles were hanging out on top of the algae, and the algae was disappearing. Well, at least we’d solved her problem about what to feed the tadpoles.
Unknown microbe hanging out in the algae.
While the filamentous algae might not be as good as the Egeria densa for plant-cell microscopy, it does host quite a number of other microbes that are fascinating to look at.
Ecological Role of Algae
Based on these observations, ecologically the filamentous algae does not just provide habitat for protists and other microbes, it also appears to be a significant source of food for larger animals, like the tadpoles, and probably also the small fish that live in the creek. Bubbles trapped under the ice. With all the algae growing in the water, and the clear ice, these bubbles may well be made of oxygen.
Therefore, I’d hypothesize that in the winter, when the fish disappear, and most of animal life is quite subdued, the algae blooms because it’s not being grazed on nearly as much (see the picture above). When the weather warms, however, it’s the turn of the algae to repressed.
It would be interesting to have a student monitor the algae growth, and the fish/tadpole population, over the course of the school year to see if the relationship is more than just coincidence.
P.S. After our last snowfall, the melting snow has put a lot of water into the creek, and all the algae appears to have been washed away.
The Australian Bureau of Meteorology recently had to add two new colors to their temperature maps because the previous colors did not go high enough.
Andrew Sullivan pulls together commentary on a recent research paper that shows that the costs of waiting to act on climate change, far outweigh the costs of acting now. The longer we wait, the more it’s going to cost to prevent the most dangerous effects of climate change. Unfortunately, the costs of waiting will be paid in the future (as will the benefits), so there’s less motivation to act now.
Two degrees is the level that is currently supported by over 190 countries as a limit to avoid dangerous climate change …
“Ultimately, the geophysical laws of the Earth system and its uncertainties dictate what global temperature rise to expect,” said Rogelj. “If we delay for twenty years, the likelihood of limiting temperature rise to two degrees becomes so small that the geophysical uncertainties don’t play a role anymore.”
On top of this, Fiona Harvey reports on an International Energy Agency report that suggests:
The world is likely to build so many fossil-fuelled power stations, energy-guzzling factories and inefficient buildings in the next five years that it will become impossible to hold global warming to safe levels, and the last chance of combating dangerous climate change will be “lost for ever”, according to the most thorough analysis yet of world energy infrastructure.
Both [thermometer and proxy] records also show that the global warming in the last 15 years of the record (1980–1995) is significantly faster than that of the long-term trend (1880–1995).
To figure out what the weather and climate were like in the past, before things like thermometers were invented, scientists use proxies such as: the change in tree ring thickness; differences in the isotopic composition of shells and rocks; records of species change in the oceans; gases in bubbles trapped in glacial ice (as well as the character of the ice itself). Paleoclimatologists at NOAA have analyzed 173 different proxy records to provide a lot more evidence that the increase in temperature we’ve been measuring for the last 150 years (with thermometers) is real.
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We took a school trip to the ski slopes in Hidden Valley. It was the interim, and it was a day dedicated to taking a break. However, it would have been a great place to talk about gradients, changes in slopes, and first and second differentials. The physics of mass, acceleration, and friction would have been interesting topics as well.
Calculus student about to take the second differential.
This year has been cooler than last year, but they’ve still struggled a bit to keep snow on the slopes. They make the snow on colder nights, and hope it lasts during the warmer spells. The thermodynamics of ice formation would fit in nicely into physics and discussion of weather, while the impact of a warming climate on the economy is a topic we’ve broached in environmental science already.
The blue cannon launches water into the air, where, if it’s cold enough, it crystallizes into artificial snow. The water is pumped up from a lake at the bottom of the ski slopes.
The footage was taken [on February 14th] in the Urals, where over 200 were injured from the impact. The meteor was likely related to the asteroid 2012 DA14, which is scheduled to graze our planet [on the 15th] at 7.25 pm EST.
Environmental Science students have been working on a wide range of term projects. They’re required to use real data. Some are using the long term weather, climate and socioeconomic records from national and international data repositories. Others are collecting their own measurements — the ability to connect temperature, pH, and conductivity sensors to the new calculators have proven invaluable.
One project that I’ve been particularly happy that someone has taken up, because of its potential future use, has been to assemble a specimen collection cataloging the vegetative biodiversity in the area around the creek. With the help of TFS parent Scott Woodbury, who works for the Missouri Botanical Gardens, she’s collected, identified, and preserved dozens of specimens. She’s also compiled them all into an online phylogenetic tree (using mind42) that should serve as a wonderful reference for future class and student projects.
