Is the 136 K calorimetric step the glass transition of water
In plain words
Glassy water made by very fast cooling shows a small heat-capacity step near 136 K, long taken as its glass transition, and a second step near 116 K was reported in high-density amorphous ice. Whether these steps mark glasses turning into ultraviscous liquids or something else is disputed.
Precise statement
Hyperquenched glassy water and low-density amorphous ice show a weak calorimetric step near $136\,\mathrm{K}$ at ambient pressure, and pressure-annealed high-density amorphous ice a step near $116\,\mathrm{K}$ (2013). Determine whether each step is a glass transition to a diffusive ultraviscous liquid (LDL or HDL) with translational relaxation time about $1\mathrm{e}2\,\mathrm{s}$, or an orientational or sub-$T_{g}$ relaxation with $T_{g}$ of water higher (near $165\,\mathrm{K}$, as argued from comparison with hyperquenched inorganic glasses in 2004). An answer is a measurement of translational diffusion or viscous flow just above each step.
What would settle it
Direct measurement of translational diffusion (isotope intermixing, viscous flow, or dielectric response tied to translation) just above 136 K and 116 K, showing liquid-like or glass-like mobility.
Status in the literature
Two glass transitions were reported in 2013 (Amann-Winkel et al., PNAS, https://doi.org/10.1073/pnas.1311718110) against the 2004 reassignment of $T_g$ near 165 K (Yue and Angell, Nature, https://doi.org/10.1038/nature02295).