GlacierHub News Report 05:10:18

GlacierHub News Report 05:10:18

The GlacierHub News Report is a bi-monthly video news report that features some of our website’s top stories. This week, GlacierHub news is featuring an interview with Sophie Elixhauser, a new study on the Atlantic Meridional Overturning Circulation, a discussion of hazardous development in Nepal, and a theory about snowballs and slushies!

 

This week’s news report features:

 

East Greenland’s Iivit Communities: An Interview with Sophie Elixhauser

By: Natalie Belew

Summary: GlacierHub interviewed anthropologist Sophie Elixhauser to discuss her recently published book, “Negotiating Personal Autonomy: Communication and Personhood in East Greenland.” She shared her perspective of her time observing the Inuits in East Greenland. She explained that she began her research in East Greenland with a very broad question about how people relate to their environment.

Read her full interview here.

 

A New Low for the Atlantic Meridional Overturning Circulation

By: Sabrina Ho

Summary: A new paper published in Nature has shown that the Atlantic Meridional Overturning Circulation has decreased drastically in strength, especially in the last 150 years. Increasing freshwater input from melting glaciers and ice sheets in the Nordic and Arctic Seas have contributed to the slowdown. GlacierHub interviewed Wallace Broecker, a well-known geoscience professor in Columbia University’s Department of Earth and Environmental Sciences who coined the term “the great ocean conveyor belt.” He claims that there are dozens of “water hosing experiments” that simulated freshwater input of higher magnitudes coming from Greenland. “Still they failed to shut down the AMOC,” he said.

Read more here.

 

Communities in Nepal Expand to Risk Areas, Despite Hazards

By: Jade Payne

Summary: A recently published study in the journal Land has found that more than a quarter of the new houses in Pokhara, the second-largest city in Nepal, are being built in highly dangerous areas susceptible to multiple natural hazards, including glacier lake outburst floods (GLOFs) and avalanches. The study lists a number of challenges for this rapidly-growing city, located in a region with a number of geological hazards. Most of the newly settled areas are located in agricultural areas, which are attractive to prospective residents because they are flat and have owners who permit construction. However, these locations place new houses at great risk. The researchers indicate that this growth will continue until at least 2035.

Read more here.

 

Was the Earth Frozen Solid

By: Tae Hamm

Summary: Many scientists are coming up with hypotheses about a global ice age during the Cryogenian geologic period that took place between 720 to 635 million years ago. Two main hypotheses are on the table: “Snowball Earth” theory, which argues that ice covered the entire Earth, and “Slushball Earth” hypothesis, where the sea near the equator stayed open, allowing the evaporation and precipitation of water to persist. However, neither of these hypotheses are set in stone, but are rather part of an ongoing debate that requires much clarification. Developing different climate models with many parameters is necessary to better understand what happened during the Cryogenian period, giving flexibility to the ever-unknown complexity of past climate conditions. Moreover, careful study of the organisms that survived during this period could further help us understand the truth behind the Cryogenian ice age.

Read more here.

 

Video Credits:

Presenters: Brian Poe Llamanzares & Sabrina Ho

Video Editor: Brian Poe Llamanzares

Writer: Brian Poe Llamanzares

News Intro: Truyền hình SVOL

Music: iMovie

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A New Low for the Atlantic Meridional Overturning Circulation

In a recent paper published in Nature, a team of researchers from Canada, the United States and the United Kingdom collaborated across the Atlantic to break ground on a new study that the Atlantic Meridional Overturning Circulation (AMOC) is at its lowest in the past 150 years.

Instrumental in regulating global climate, the AMOC transports heat from the tropics and southern hemisphere toward the North Atlantic and the atmosphere. The strength of the AMOC varies periodically on a 60 to 80 year timescale, which is known as the Atlantic Meridional Oscillation. Currently in its negative phase, a weakening of the AMOC is often associated with the cooling of the Northern Hemisphere. However, it has other widespread impacts on American, African and Asian monsoons.

While other studies have shown that the AMOC has been weakening in recent years, the team demonstrated that the strength of the AMOC is at its lowest in 1,500 years, a finding that is cause for great concern. The researchers also suggested that the magnitude of decline has been severely underestimated due to the lack of sensitivity toward climate (freshwater) forcing. As meltwater is added into the oceans, changes in salinity and water density occur, which disrupt oceanic circulation patterns.

The Global Thermohaline Circulation System, with the AMOC boxed in red (Source: Authorship.me / Twitter).

One such example is the weakening of the circulation in the Labrador Sea as suggested by paleo-oceanographic evidence. This was determined by sorting the size of sediment grains deposited on the ocean bed, which showed a decrease in velocity of the Labrador Sea deep western boundary current.

The deep Labrador Sea density is always used as a predictor for changes in AMOC strength. As the Labrador Sea convection weakens, the velocity of the deep western boundary current decreases, which in turn decreases AMOC strength. This is attributed to freshwater inputs as Arctic and Nordic sea ice, ice sheets, and glaciers started to melt, which is usually thought to have been the outcome of the end of the Little Ice Age in the mid-nineteenth century.

Meanwhile, various methods and models were also used to reconstruct the surface temperatures of regions affected by the AMOC. In an interview following the publication of the study, lead author David Thornalley, a senior lecturer at University College London. stated that the “AMOC has weakened over the past 150 years by approximately 15 to 20 percent.”

Yet, the researchers results indicate the onset of AMOC weakening during the late Little Ice Age, coinciding with the industrial era. At that time, increased activity of exporting Arctic and Nordic sea ice occurred, coupled with melting circum-Arctic ice shelves.

In the same interview, Thornally had asserted that “warming and melting are predicted to continue in the future due to continued carbon dioxide emissions.” This comes as no surprise, with many studies already proving that global temperatures have been steadily increasing since the Industrial Revolution.

As the AMOC represents a dynamic coupled ocean-atmosphere system, it can be viewed as both a driver or a responder to climate change. In this case, the study believes that the AMOC has largely responded to the recent century and a half of climate change. Nonetheless, as stated in their report the AMOC may have “modified northward ocean heat transport, as well as atmospheric warming by altering ocean–atmosphere heat transfer, underscoring the need for continued investigation of the role of the AMOC in climate change.”

Thankfully, the AMOC is unlikely to completely shutdown. In an interview with GlacierHub, Wallace Smith Broecker, a well-known geoscience professor in Columbia University’s department of Earth and Environmental Sciences, said, “For what it’s worth, there are dozens of ‘water hosing’ experiments” that simulated freshwater input of higher magnitudes coming from Greenland. “Still they failed to shutdown the AMOC,” Broecker added.

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