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Author Topic: Glaciers of New Guinea  (Read 958 times)

ArcticMelt2

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Glaciers of New Guinea
« on: June 09, 2019, 09:41:08 AM »
This year may be the last for the glaciers of one of the largest islands on the planet.

https://en.wikipedia.org/wiki/Carstensz_Glacier
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The remaining remnant glaciers on Punkak Jaya were once part of an icecap that developed approximately 5,000 years ago. At least one previous icecap also existed in the region between 15,000 and 7,000 years ago, when it also apparently melted away and disappeared.[1]

https://earthobservatory.nasa.gov/images/91716/glaciers-in-the-tropics-but-not-for-long

November 3, 1988



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The top image shows that, as of 1988, five masses of ice rested on the mountain slopes.

October 9, 2009



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By 2009, the Meren and Southwall glaciers had disappeared, and the Carstensz, East Northwall Firn, and West Northwall Firn had retreated dramatically.

December 5, 2017



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By the time OLI acquired the 2017 image, the West Northwall Firn had also disappeared. Turn on the image comparison tool to see the changes.

ArcticMelt2

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Re: Glaciers of New Guinea
« Reply #1 on: June 09, 2019, 09:42:43 AM »
In general, out of 5 glaciers in 1988, in 2017 only a couple of glaciers remained.

ArcticMelt2

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Re: Glaciers of New Guinea
« Reply #2 on: June 09, 2019, 10:09:27 AM »
In 2010, the glaciers were drilled.

https://etd.ohiolink.edu/pg_10?::NO:10:P10_ETD_SUBID:74839#abstract-files

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A field expedition to Papua highland was conducted in May - June 2010 to drill ice cores from these glaciers and to collect rain samples from different elevation in the vicinity.

Three ice cores were drilled, two to bedrock measuring 32.13 m (D1) and 31.25 m (D1B) in length and the third measuring 26.19 m (D2) in length. The stable isotope records were reproducible between the longer cores with significant δ18O variability of 5 to 6‰. High aerosol events were identified between 20 and 29 meters depth and in the top eight meters. This suggests that there is no melting throughout the glacier. The dating of D1 core has not been completed yet. Low tritium concentration in D1 core and high tritium concentration recorded in precipitation at the northern sites of Papua suggests that the glaciers may have melted below the 1950s/1960s bomb horizons.

ArcticMelt2

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Re: Glaciers of New Guinea
« Reply #3 on: June 09, 2019, 10:16:41 AM »
Presumably the glaciers already completely melted in the 20-30s of the 20th century.

https://etd.ohiolink.edu/pg_10?0::NO:10:P10_ACCESSION_NUM:osu1449155469

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The age of the D1 (D1B) core is ~90 yrs (~77 yrs) with a bottom age of 1920 (1933). The ice core dating is based on tritium analysis which provides an absolute time marker of 1964 at a depth of 23.4 m in Core D1, and δ18O reference-matching with NINO3.4 sea surface temperature (SST). On decadal to interdecadal timescales, dust and major ions concentration in the ice cores are modulated by El Niño-Southern Oscillation (ENSO) activity and Pacific Decadal Oscillation (PDO) phases. On an interannual timescale peaks of dust, ammonium and potassium are associated with El Niño-linked drought and biomass burnings. The D1 δ18O time series shows an increasing trend from 1920 to 2010 with a slope of 0.012‰ per year which is identical with the trend of the regional temperatures over Papua region suggesting that atmospheric warming controls δ18O variation. In contrast, annual precipitation rate shows contemporaneous positive trend that contradicts the amount effect as a major factor. During El Niño, precipitation 18O is enriched, aerosol deposition on the glacier surface is enhanced due to the exposure of more dust sources, and accumulation is low with most precipitation falling as rain rather than snow. During La Niña, precipitation 18O is depleted, higher precipitation and cooler temperatures prevail in the highland which results in higher snow accumulation.

Previous studies indicates that the total ice area near Puncak Jaya has decreased at a rate of ~0.15 km2 per year since ~1850, which implies that these glaciers will disappear by ~2017-18. This is consistent with personal observations made during the 2010 ice core drilling campaign where ice around a tent at the campsite had melted a 30 cm after ~3 weeks camping on the ice field, suggesting a thinning rate of ~5.2 m/yr. A recent accumulation stake measurement on the ice surface indicates that the ice thickness has thinned by ~5.26 m between 2010 and 2015 (~1.05 m/yr), which provides the upper bound of the date for the glaciers disappearance by ~2040. The south ice front of the East Northwall Firn has experienced an accelerated retreat rate from ~14 m/yr between 1936 and 2006 to ~51 m/yr between 2006 and 2015 which is most likely due to atmospheric warming.

ArcticMelt2

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Re: Glaciers of New Guinea
« Reply #4 on: June 09, 2019, 10:25:30 AM »
Presumably the glaciers already completely melted in the 20-30s of the 20th century.

Although it is very doubtful. Glaciers at that time existed and were much larger than they are now (probably the ice has great mobility).