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Tag Archives: ice

Glacier Pairs

NASA’s Global Ice Viewer for Glaciers provides stunning pairs of images of glaciers taken many years apart at the same location. The viewer starts with a map of the world with links for seven locations. Each link brings you to glacier pair images from that location with information about the images. For example, here is a pair of images from Bear Glacier in the Alaskan Range. The top image was taken on July 20, 1909 and the second on Aug 5, 2005. Here is what the site says about glaciers:

Glaciers are sentinels of climate change. Ice that took centuries to develop can vanish in just a few years. A glacier doesn’t melt slowly and steadily like an ice cube on a table. Once glacial ice begins to break down, the interaction of meltwater with the glacier’s structure can cause increasingly fast melting and retreat.

Widespread loss of glaciers would likely alter climate patterns in complex ways. Glaciers have white surfaces that reflect the sun’s rays.  This helps keep our current climate mild. When glaciers melt, darker surfaces are exposed, which absorb heat.  This raises temperatures even more.

Larsen C Update

Project MIDAS recently posted Larsen C takes another step towards calving.

In the largest jump since January, the rift in the Larsen C Ice Shelf has grown an additional 17 km (11 miles) between May 25 and May 31 2017. This has moved the rift tip to within 13 km (8 miles) of breaking all the way through to the ice front, producing one of the largest ever recorded icebergs. The rift tip appears also to have turned significantly towards the ice front, indicating that the time of calving is probably very close.

STEM folks are presented with challenging problems modeling and predicting changes in ice and glaciers due to climate change.

Arctic Sea Ice Visual

Thanks to the folks at the NASA Scientific Visualization Studio for this visualization of Annual Arctic Sea Ice Minimum 1979-2015 with Area Graph (click on the visual to play). Arctic ice data is available in the calculus and statistics sections. A recent Economist article The thawing Arctic threatens an environmental catastrophe adds some context.

The Arctic has been warming at twice the rate of the rest of the world for decades because of feedback loops that have reduced the albedo effect, a measure of the way Earth reflects heat. Unlike the rest of the planet the polar regions release more heat into space than they absorb, in effect cooling the planet, because sunlight is reflected by ice and snow. When it is replaced by water or dark ground, more heat is retained. That is precisely what is happening in the Arctic’s defrosting landscape.

Larsen C in the News

The crack in the Larsen C ice shelf has been in the news recently. For instance Newsweek’s Another Huge Crack has Appeared on the Antarctica’s Larsen C Ice Shelf or the BBC’s The Crack that is Redrawing the World’s Map. Both articles seem to stem from the Project Midas news release A new branch of the rift on Larsen C (they made the map here).  The Newsweek article notes:

Current projections indicate that if the Larsen C ice shelf disintegrates, it could raise sea levels by up to 10cm.

A NASA report, Breaking the ice: Antarctic rifts and future sea level is a little more precise:

Yet even if the whole ice shelf were to break up, Fricker said, the resulting sea level rise would be minimal. The glaciers held back by the shelf are not so imposing.

“The Larsen C ice shelf only holds back about one centimeter of global sea level rise,” she said.

Still, the crack in Larsen C could be a bellwether for ice shelves elsewhere on the continent, Rignot said.

“What we are seeing on Larsen C has implications for the big ice shelves farther south that hold considerable (sea level) potential,” he said. The loss of these larger ice shelves and the resulting acceleration of glacial calving could amount to meters of sea level rise in the decades and centuries to come.

The NASA article does provide some balance:

Ice shelf demise, or business as usual?

The crack could be the start of a period of sustained retreat, similar to what happened to Larsen B, said Ala Khazendar, a JPL scientist who has investigated both Larsen B and Larsen C. An increasingly weakened ice shelf allows glaciers to speed their flow into the ocean, and the shelf, unable to recover its former bulk and solidity, disintegrates.

Or, this could turn out to be a normal calving episode.

“We have no way yet of knowing whether Larsen C is doing what Larsen C has been doing for thousands of years, or whether we are witnessing the beginning of the end of Larsen C,” he said.

If you are talking about climate change in the classroom, the NASA article is excellent for further readings and discussion as well as the Project Midas site. There is some interesting science here in understanding ice.

Greenland Ice Mass and Data

Vital Signs of the Planet from NASA is a place for graphs and data. The graph here is change in the mass of the Greenland Ice Sheet. On the Land Ice page there is also a graph of changes in the Antarctica Ice. Underneath each graph is a link to data (HTTP), which will give you data for both Greenland and Antarctica ice as well as sea level change. All three sets can be used for linear regression or multiple regression predicting sea level change based on both ice mass changes (recall that melting sea ice doesn’t raise sea levels but land ice does).

Antarctica Ice Hits a Record Low

The WunderBlog has an excellent summary of the current state of Antarctica Ice in their post Sea Ice Extent in Antarctica Bottoming Out at Lowest on Record.  The chart here comes from the NSIDC Interactive Chart and is a full version of the one in the article.

A few tips on using the interactive chart.  On the top left you can click to get a chart for Antarctic or the Arctic. In the top right of the years menu there is a button to press that allows you to download the chart you create as a jpeg or png file. The bottom of the years menu has a scroll down button to get to more recent years. The chart is updated daily.