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Author Topic: Kilimanjaro Glaciers  (Read 941 times)

ArcticMelt2

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Kilimanjaro Glaciers
« on: June 09, 2019, 07:45:39 AM »
It is believed that this is one of the oldest glaciers on the planet.

https://en.wikipedia.org/wiki/Mount_Kilimanjaro
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Because of the exceptionally prolonged dry conditions during the subsequent Younger Dryas stadial, the ice fields on Kilimanjaro may have become extinct around 11,500 years BP.[81] Ice cores taken from Kilimanjaro's Northern Ice Field (NIF) indicates that the glaciers there have a basal age of about 11,700 years,[83] although an analysis of ice taken in 2011 from exposed vertical cliffs in the NIF supports an age extending only to 800 years BP.[84] Higher precipitation rates at the beginning of the Holocene epoch (11,500 years BP) allowed the ice cap to reform.[81] The glaciers survived a widespread drought during a three century period beginning around 4,000 years BP.[81][85]

Now this 12-thousand-year-old ice is on the verge of total destruction.

http://kiboice.blogspot.com/2019/02/19-years-on-northern-icefield.html

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This week marks 19 years since AWS measurements began on Kilimanjaro's Northern Icefield (NIF). With enthusiastic help from our Tanzanian crew, Mathias Vuille and I installed a tower into the ice and connected the electronics. Remarkably, the same datalogger continues measurement and control functions, and the same solar panels continue to provide power. Most sensors have been swapped out for recalibration or replacement, yet the original barometric pressure sensor continues reliable measurements every hour.

Ice ablation since 2000 has substantially reduce the areal extent of all glaciers on the mountain. However, this portion of the NIF has "only" thinned by ~5 meters, because the low surface gradient retards meltwater runoff - which then refreezes in place as superimposed ice. Other portions of the NIF, and other glaciers, have thinned more dramatically. For example, ice no longer remains at February 2000 drill sites on the Furtwängler and Decken Glaciers, which were 9.5 and ~20 m thick at the time (respectively).

For comparison, the length of the longest cores of the Northern glacier does not exceed 50 meters:
https://byrd.osu.edu/research/groups/ice-core-paleoclimatology/projects/tanzania/kilimanjaro
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In January and February of 2000, six ice cores were drilled to bedrock from the three remnant ice fields on the rim and summit plateau atop Kilimanjaro (3° 03.7' S; 37° 21.2' E; 5893 m asl). The three longest cores (NIF1, NIF2, NIF3) were drilled to depths of 50.9, 50.8, and 49.0 meters, respectively, from the Northern Ice Field (NIF), the largest of the ice bodies.

Now this glacier is 5 meters thinner.

The radar in 2015 confirms that the thickness of this glacier is not more than 50 meters.

https://www.the-cryosphere.net/11/469/2017/

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The GPR profiles reveal an ice thickness ranging between (6.1 ± 0.5) and (53.5 ± 1.0) m. Combining these data with a very high resolution digital elevation model we spatially extrapolate ice thickness and give an estimate of the total ice volume remaining at NIF's southern portion as (12.0 ± 0.3) × 106 m3.

ArcticMelt2

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Re: Kilimanjaro Glaciers
« Reply #1 on: June 09, 2019, 07:59:02 AM »
The radar in 2015 confirms that the thickness of this glacier is not more than 50 meters.

https://www.the-cryosphere.net/11/469/2017/

Quote
The GPR profiles reveal an ice thickness ranging between (6.1 ± 0.5) and (53.5 ± 1.0) m. Combining these data with a very high resolution digital elevation model we spatially extrapolate ice thickness and give an estimate of the total ice volume remaining at NIF's southern portion as (12.0 ± 0.3) × 106 m3.

In this work, there is a graph of how the thickest part of the oldest glacier falls.

This definitely proves that critical temperatures have already been reached, which are maximum for at least the last 12 thousand years.

ArcticMelt2

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Re: Kilimanjaro Glaciers
« Reply #2 on: June 09, 2019, 08:13:50 AM »
Map of the thickness of the last and oldest pieces of African ice.

ArcticMelt2

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Re: Kilimanjaro Glaciers
« Reply #3 on: June 09, 2019, 08:25:51 AM »
The last map shows that in 2000 they drilled not in the thickest part of the glacier. In this regard, the ice Kilimanjaro may even be older than 12 thousand years. Theoretically, it could survive since the last interglacial time 140 thousand years ago.

I hope scientists will have time to re-drill the glacier before it finally melts.