An 11-million-ton iceberg is threatening a tiny village in Greenland

photo : Ritzau Scanpix / Karl Petersen / via Reuters
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From The Washington Post by Cleve R. Wootson Jr.

An 11-million-ton iceberg is parked precariously close to the tiny village of Innaarsuit — a glacial faceoff that pits 169 residents of Greenland against the biggest iceberg many have ever seen.

Their fate could be entirely dependent on the weather forecast.

If a strong enough wind blows at the right time, the berg could be dislodged from the spot where it has grounded, and float harmlessly into Baffin Bay.
Crisis over.

Cpernicus Emergency Management Service EMSR297: Iceberg in Greenland

But if Mother Nature brings enough rain, the relatively warm precipitation could further destabilize the iceberg, potentially sending a chunk of it into the ocean and creating a tsunami that could wash away part of the town.
“We are very concerned and are afraid,” Karl Petersen, chair for the local council in Innaarsuit, told the Canadian Broadcasting Corp.
So far, 33 people have been moved to safer places inland.
Others have been encouraged to move their boats away from the iceberg.

Innaarsuit on the West coats of Greenland (DGA nautical chart with the GeoGarage platform)

Innaarsuit is about 600 miles north of Nuuk, the country's capital.
The village's residents are mostly hunters and fishermen in an isolated area most easily reached by boat or helicopter.

The iceberg is 650 feet wide — nearly the length of two football fields — and rises 300 feet above sea level, according to the New York Times.
In terrifying pictures, it literally casts a shadow on a hilly outcropping of Innaarsuit, dwarfing boats, homes and businesses.

 Sentinel-2 09-07-2018

Residents don't need lengthy memories to know the effect even a small tsunami could have on the country that doubles as the world's biggest island.

Last June, according to Quartz, a landslide caused by a 4.1-magnitude earthquake that struck 17 miles north of the village of Nuugaatsiaq partly triggered a tsunami that washed away 11 homes and killed four people.
Video posted online showed villagers sprinting away from approaching waves washing over seaside homes.

Tsunamis caused by landslides in bays can rise to incredible heights, travel at devastating speeds, and cause massive destruction, according to Quartz.
A similar giant wave was thought to have destroyed the city of Geneva in 563 AD, the Economist wrote.

Of course, even if there isn't some giant city-destroying Hollywood-style tsunami, there are other dangers from rising water.
Nearby rivers could overflow their banks, for example, threatening homes and other buildings that don't face the sea.
And Innaarsuit's power plant is also on the coast, meaning flooding in a very specific place could send Innaarsuit into the Dark Ages.

A Danish Royal Navy ship is standing by, according to the CBC, in case the situation sours.
“We can feel the concern among the residents,” Susanna Eliasson, a member of the village council, told CBC.
“We are used to big icebergs, but we haven’t seen such a big one before.”

For now, the residents of Innaarsuit are watching the weather.
The area will see relatively sedate winds for the next week.
And on Sunday, July 22, it's supposed to rain.

Links :

• NPR : Massive Iceberg Looms Over A Village In Greenland

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NYU scientists capture 4-mile iceberg breaking in Greenland

A team of NYU scientists has captured on video a four-mile iceberg breaking away
from a glacier in eastern Greenland.

This phenomenon, known as "calving", is a force behind the rise of global sea water levels.

“Global sea-level rise is both undeniable and consequential,” observes David Holland, a professor at NYU’s Courant Institute of Mathematics and NYU Abu Dhabi, who led the research team.

“By capturing how it unfolds, we can see, first-hand, its breath-taking significance.”

Holland’s research team has studied the waters off the coast of Greenland for more than a decade by measuring subtle changes in water temperature and wave formation.

Video Credit: Denise Holland, Logistics Coordinator/NYU’s Environmental Fluid Dynamics Laboratory (Video shot June 22, 2018- Real time length: 30 minutes)

 Helheim glacier DGA nautical chart with the GeoGarage platform

Helheim glacier observed by NASA 

Links :

• Washington Post : Watch 10 billion tons of ice fall into the ocean
• Eather : An Iceberg the Size of Lower Manhattan Just Broke off Greenland 

Australia (AHS) layer update in the GeoGarage platform

7 nautical raster charts updated

see GeoGarage news

 "New Holland and New Guinea" 1798

Stanford study reveals the pulse of the polar vortex – and a key to mapping future storms

ESA’s Aeolus mission scientist, Anne Grete Straume explains how winds are generated, how they affect our weather, and how Aeolus will measure the wind and how this information will be used to improve weather forecasts and climate models.

From Standford University by Josie Garthwaith


A new analysis of how air moves between two layers of Earth’s atmosphere reveals a deep system that could enable long-term weather forecasts and better climate models.

If you can predict the path of the jet stream, the upper atmosphere’s undulating river of wind, then you can predict weather – not just for a week or two, but for an entire season.
A new Stanford study moves toward that level of foresight by revealing a physical link between the speed and location of the jet stream and the strength of the polar vortex, a swirl of air that usually hovers over the Arctic.

“The jet stream sets everything,” said Aditi Sheshadri, lead author and assistant professor of Earth System Science in the School of Earth, Energy, & Environmental Sciences (Stanford Earth).
“Storms ride along it.
They interact with it.
If the jet stream shifts, the place where the storms are strongest will also shift.”

The research, published in the Journal of Atmospheric Sciences, identifies two distinct modes in how air flows within the jet stream and the layers of atmosphere that sandwich it.

 Alex (IK MetOffice) explains the Polar Vortex.

The atmosphere’s deep system

In one mode, changes in wind speed and direction start close to the equator in the troposphere, the wet, stormy layer of atmosphere below the jet stream and closest to Earth’s surface.
Shifts of wind in this mode quickly propagate up through the jet stream and into the polar vortex in the dry, upper layer of atmosphere known as the stratosphere.

In the other mode, the strength of the stratosphere’s polar vortex influences the path and strength of the jet stream – and how it interacts with storms in the troposphere.
In this mode, the polar vortex sends a signal all the way down to the surface like a pulse.
A weaker vortex produces a weak jet stream that slips toward the equator; a stronger vortex intensifies the jet stream while drawing it poleward.

“These deep vertical structures haven’t been shown before,” Sheshadri said.
“It’s something fundamental about the system itself.” Her analysis could help explain the surface weather impacts of an event that occurred in early 2018, when the vortex weakened so much that it ripped in two – a phenomenon that scientists know can blast up to two months of extreme weather into western Europe.
Until now, understanding of these interactions has been based on observations and statistical modeling rather than knowledge of their physical foundation.

These modes could be key to predicting the long-term effects of certain environmental changes on Earth’s surface.
While air is thought to flow relatively independently within the troposphere and stratosphere in normal winters, depleted ozone, high levels of greenhouse gases, ocean warming, reduced snow cover, and other disturbances can rattle this independence, affecting both the vortex and jet stream in complex ways.
Greenhouse gas emissions, for example, can strengthen the vortex while simultaneously boosting waves that propagate up from the troposphere and weaken the vortex as they break.

“We don’t know which of these two effects of increasing greenhouse gases will win out,” Sheshadri said.

Changes in wind speed and direction that start in the troposphere close to the equator quickly propagate up toward the stratosphere and poles.

(Image credit: Aditi Sheshadri)

Building better climate models

To help find answers, Sheshadri’s team set out to understand the climate as a system that responds in a predictable way to known forces, despite internal dynamics that are a mix of random and systematic fluctuations.
They took a mathematical theorem used for nearly a century to predict seemingly random behavior in quantum mechanical systems and applied it to data representing Earth’s atmosphere in wintertime.

“We have 35 years of wind data,” Sheshadri said.
“Can we say something just from those observations about how the winds will change if, for instance, you increase carbon dioxide? That’s what got this whole thing started.”

Current climate models excel at showing temperature changes throughout the atmosphere’s layers over time and with varying levels of substances like ozone or carbon dioxide.
“We’re pretty certain about how the temperature structure of the atmosphere is going to change,” Sheshadri said.
“However, if you look at changes in things like wind or rain or snow – anything that’s a dynamical quantity – we really have very little idea of what’s going on.”

And yet, these are some of the most vivid metrics for a changing climate.
“No one feels the global mean temperature,” Sheshadri said.
“How many times over the next 10 years are we going to have to deal with floods or cold snaps in a particular region? That’s the sort of question this might help answer.”

By revealing the physical processes that underpin some of these dynamic variables, the method developed in this study could also help weed out flaws in climate models.

“The way that we currently do this is that you take a model and you run it forward,” checking the model’s predictions against observed data, Sheshadri explained.
But many models built upon the same historic data produce different predictions for the future, in part because they make different assumptions about how the troposphere and stratosphere interact and how the jet stream fluctuates.
Until now there has not been a way to check those assumptions against the atmosphere’s actual variability.

“We need to be sure the models are right, and for the right reasons,” Sheshadri said.
The new work provides a way to resolve that uncertainty – and to anticipate storms months into the future.

Links :

• Forbes : Splitting Of The Polar Vortex: The Arctic Is Melting In The Dead Of Winter
• GeoGarage blog : What happened to the Polar Vortex? / Arctic warming: scientists alarmed by 'crazy ... / Warming Arctic may be causing Jet Stream to lose ...