Reviewer Comments

This is a valuable paper that enhances evapotranspiration estimates by incorporating CO₂ physiological feedback and CMIP6 scenarios, which is of great significance for understanding hydrological processes under climate change. The study contributes to improving the accuracy of future ET projections and provides insights for related research.

The data and methodology are generally sound, and the manuscript is well-structured and comprehensive. This study extends previous research by updating the Penman-Monteith model based on CMIP6 data, and it fits within the scope of relevant journals, which will be of interest to readers.

I recommend this work for publication after some minor revisions.

Comments

1. In the Abstract, the phrase "reduces the deviation in projected ET trends by approximately 15–20%" should be revised to "reduces the deviation in projected ET trends by approximately 15–20% compared to CMIP5-based frameworks" for improved clarity.
2. The keywords are relevant, but it is suggested to add "Penman-Monteith model" to better reflect the methodological core.
3. In the Introduction, when describing "Yang et al. (2019) model", it is recommended to supplement a brief note on its key parameter (e.g., original coefficient 2.4×10⁻⁴) to lay a clearer foundation for the subsequent update to 1.9×10⁻⁴.
4. In Section 2.1, when mentioning "resampled to a uniform spatial resolution of 0.25° × 0.25°", it is suggested to specify the resampling method (e.g., bilinear interpolation) for reproducibility.
5. In Section 2.2, the criteria for "non-water-limited regions" (e.g., "ET/P ratio < 2.0") are clear, but it is recommended to add a brief explanation of why this threshold is chosen (e.g., based on previous studies) to improve rigor.
6. The formulas in Sections 2.3.2–2.3.4 use symbols like "s", "γ", and "u". It is suggested to add a unified list of symbols at the end of the paper or in an appendix to avoid confusion for readers.
7. Figure 1 (Taylor diagrams) lacks explicit units for variables (e.g., relative humidity in %). It is recommended to add units in the figure caption to enhance clarity.
8. In Section 3.2, "Ep intensification rates vary by scenario: under SSP5-8.5, the decadal increase is approximately 2.1%" – it is suggested to specify the reference period (e.g., relative to 2015–2025) for this rate.
9. Figure 5 (time series decomposition) has subplots labeled (a)–(d) corresponding to SSP scenarios, but the caption does not explicitly link each subplot to the scenario (e.g., "(a) SSP1-2.6, (b) SSP2-4.5..."). It is recommended to add this correspondence to help readers.
10. In Section 4.1, "low-emission scenarios exhibit more dispersed distribution across models", but it is suggested to briefly cite 1–2 relevant studies (e.g., Pan et al., 2020) to support this observation and strengthen the discussion.
11. The limitations section (4.2) notes that the model "assumes fixed vegetation responses to CO₂". It is suggested to add a short sentence on how future work could relax this assumption (e.g., integrating species-specific parameters) to make the prospects more concrete.
12. In the Conclusion, "improved consistency with CMIP6 data" is suggested to be rephrased as "improved consistency with CMIP6 simulations" to align with terminology used in the main text.