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Tag Archives: climate change

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.

A Feedback Loop: The Alaska Tundra

A recent NASA report Alaska tundra source of early-winter carbon emissions provides another example of a feedback loop. Global warming has slowed the refreezing of the Alaska tundra allowing for increased CO2 releases.

A new paper led by Roisin Commane, an atmospheric researcher at Harvard University in Cambridge, Massachusetts, finds the amount of carbon dioxide emitted from northern tundra areas between October and December each year has increased 70 percent since 1975.

“In the past, refreezing of soils may have taken a month or so, but with warmer temperatures in recent years, there are locations in Alaska where tundra soils now take more than three months to freeze completely,” said Commane. “We are seeing emissions of carbon dioxide from soils continue all the way through this early winter period.”

How much carbon is stored in the frozen soils. According to the report

The soils that encircle the high northern reaches of the Arctic (above 60 degrees North latitude) hold vast amounts of carbon in the form of undecayed organic matter from dead vegetation. This vast store, accumulated over thousands of years, contains enough carbon to double the current amount of carbon dioxide in Earth’s atmosphere.

April Second Warmest on Record

A NASA report notes that April 2017 was second-warmest April on record.

April 2017 was the second-warmest April in 137 years of modern record-keeping, according to a monthly analysis of global temperatures by scientists at NASA’s Goddard Institute for Space Studies (GISS) in New York.

Last month (meaning April) was 0.88 degrees Celsius warmer than the mean April temperature from 1951-1980. The two top April temperature anomalies have occurred during the past two years.

If you like the cool map here that was in the NASA report you can make your own for various time period at Global Maps from GHCN v3 Data. This is a great app and can be used for discussions about means vs distributions in stats or QL classes, for example. The article also has links to data sources.

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.

Climate Change, Melting Permafrost, and Disease

This blog has already noted a the feedback loop from melting permafrost, Methane Bubbles – A Feedback Loop. A recent BBC article, There Are Diseases Hidden In Ice And They Are Waking Up – Long-dormant bacteria and viruses, trapped in ice and permafrost for centuries, are reviving as Earth’s climate warms, is a well referenced article about the possible consequences of melting permafrost (picture from the article with caption: Bacteria have been found dormant in Antarctic ice (Credit: Colin Harris/Era Images/Alamy)).

“Permafrost is a very good preserver of microbes and viruses, because it is cold, there is no oxygen, and it is dark,” says evolutionary biologist Jean-Michel Claverie at Aix-Marseille University in France. “Pathogenic viruses that can infect humans or animals might be preserved in old permafrost layers, including some that have caused global epidemics in the past.”

If you are incorporating climate change issues in the classroom then the article provides for excellent classroom discussions with interesting science. The article concludes:

How much should we be concerned about all this?

One argument is that the risk from permafrost pathogens is inherently unknowable, so they should not overtly concern us. Instead, we should focus on more established threats from climate change. For instance, as Earth warms northern countries will become more susceptible to outbreaks of “southern” diseases like malaria, cholera and dengue fever, as these pathogens thrive at warmer temperatures.

The alternative perspective is that we should not ignore risks just because we cannot quantify them.

“Following our work and that of others, there is now a non-zero probability that pathogenic microbes could be revived, and infect us,” says Claverie. “How likely that is is not known, but it’s a possibility. It could be bacteria that are curable with antibiotics, or resistant bacteria, or a virus. If the pathogen hasn’t been in contact with humans for a long time, then our immune system would not be prepared. So yes, that could be dangerous.”

It would be nice if these articles discussed the populations most at risk. It is often the case that those of lower socioeconomic status are more vulnerable.  Many issues related to climate change have both a social justice component, as well as an ethical question related to the fact that those that contribute little to climate change are often impacted disproportionately.

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).