This manuscript is well-organized contribution to our understanding of how early Eocene paleogeography shaped mid-latitude circulation, cyclone activity and blocking. The modeling setup is appropriate, and the comparison between pre-industrial (PI) and early Eocene conditions is clearly motivated. The main conclusions are convincing and broadly consistent with earlier DeepMIP work. That said, some sections are quite dense, a few claims could use clearer supporting evidence,and there are places where the writing becomes a bit repetitive. With some tightening and clarification.. the paper will be even stronger.

Major Comments

1. Lines 5–10: The abstract is informative but a bit crowded. You could shorten the background on DeepMIP so the focus stays on what this study finds.

2. Line 10: The phrase “In parallel, a decrease in heat transport…” reads abruptly. Maybe say something like: “Motivating our blocking analysis, previous DeepMIP results showed…”

3.  The core message.. more cyclones in the Northern Hemisphere and fewer in the Southern Hemisphere.. Is clear and well placed.  The paleogeographic background (Lines 15–30) is good, but dense. A single summary line linking the geological setup to atmospheric circulation would help.

4. Line 21: The “C-shaped distribution of landmass” might confuse some readers. Adding a short explanation or pointing to a figure would help.

5. Lines 24–31: This section jumps quickly between monsoons, carbon cycle changes, and ice ages. Tightening it around “how paleogeography shapes climate circulation” would improve the flow.

6. Lines 35–45: The EECO description is well supported, but the number of proxies cited slows the narrative. You could trim a bit here.

7. Lines 45–55: When referring to Kelemen et al. (2023), it would help to briefly restate what changed in the heat transport components (e.g., stronger transient eddy transport in NH).

8. Lines 60–63: The goals are clear but could be merged to avoid repeating ideas.

9. Lines 75–90: Good justification for using 6-hourly data. If any spin-up was discarded, mention that explicitly.

10. Lines 80–85: Clarify whether atmospheric initial conditions came directly from the DeepMIP runs or were re-initialized.

11. Lines 95–101: The tracking thresholds ( ( >1 day) 20 hPa, 1000 kmdistance ) are standard, but a short sentence explaining why these values are chosen would help readers not familiar with cyclone tracking.

12.  The blocking index description is long in lines 103–112. Consider moving most of it to supplementary material and keeping a short summary here.

13. Line 110: Explain why you remapped to 2.5° resolution; readers may wonder whether this reduces blocking sensitivity.

14. Lines 115–125: The explanation of NH vs SH cyclone changes is clear. Refer explicitly to Fig. 3a–d in the text to guide readers.

15. Line 120: 36% increase and 32% decrease are large values. Clarify whether these are annual averages or seasonal means? or include uncertainty if possible.

16. Since you used cyclones as a stand-in for transient eddies (Line 125).. it may help to point that out more directly

17. Lines 124–130: The eastward shift in NH blocking is interesting. A short explanation of why the West Siberian Sea environment favors blocking (thermal contrast ? moisture? ) would strengthen the argument.

18. Line 129: When you say “similar intensity,” specify whether this means statistically similar or just visually comparable.

19. Lines 130–140: The moisture transport explanation is good. Adding a mention of storm-track–orography interaction would make it even clearer.

20.  Increased precipitation over western North America deserves a bit more detail @Line 134. It is likely linked to orographic lifting combined with more incoming tracks.

21. Lines 141–150: Nice summary of heat transport changes. You might add a simple clarifying sentence like: “These differences appear despite similar total MHT, due to Bjerknes compensation.”

22. Lines 155–160: The reason for increased NH baroclinicity could be elaborated—does it come mostly from stronger thermal contrasts or increased moisture supply?

23. Line 160: When discussing the absence of the ACC, briefly explain the physical tie between ACC, baroclinicity, and storm-track strength.

24. Lines 165–170: The statement that the Southern Hemisphere jet is weaker should be backed by a figure or numbers.

25. The link between OHT changes and deep-water formation is well made; one extra sentence tying this to energy balance constraints would be helpful (Line 170)

26. Lines 183–190: This summary is strong. A simple schematic showing the West Siberian Sea’s influence on baroclinicity would make the mechanism clearer.

27. Line 190: Instead of “We hypothesise…,” you might soften to “These results suggest…”

28. Line 195: The mention of future high-CO₂ simulations is good. Briefly state what specific questions those runs will address.

29. Figures 3 and 5: These are strong figures. Adding contour lines of precipitation would sharpen this spatial feature.

30. Figure 8: Latent + sensible heat fluxes are important, but splitting them or showing anomalies might make interpretation easier.

31. Figure 9: Adding wind vectors or streamlines would help readers visualize circulation, not just magnitude.

Minor:

1. Line 128: “More dispersed distribution” Lets specify whether you mean geographically or in frequency.

2. Throughout....: The explanation of OHT/AHT compensation appears multiple times; consider reducing repetition!!

3. References: Solid overall, though a couple more recent studies on Eocene storminess and SST gradients could be helpful.

The authors investigated the role of paleogeography on large-scale circulation during the early Eocene. They analyzed cyclone tracks and blocking systems of the early Eocene in an atmosphere-only CESM1.2 simulation. The results show that, paleogeographic features of the early Eocene enhanced cyclonic activity at northern mid-latitudes while reduced it at southern mid-latitudes compared to modern conditions. Overall, this paper has clear structure with enough contents. I think it can be published after revision.

Lines 3-4, Apart from these two, are there any other factors?

Lines 8-9, the details of experiments can be deleted in the abstract.

Line 38, ‘At this time in the past’, it is unclear.

Line 65, for the first part, this paper does not separate the signals related to paleogeography and CO2, please check.

Line 85, why the authors use the results from the atmosphere-only model but not the coupled CESM, please state the advantages.

Line 120, what is the relationship between cyclone distribution and the number of cyclones? For example, under early Eocene conditions, the distinction between two sets of Northern Hemispheric cyclone paths becomes less pronounced, and the number of cyclones decreases in the Northern Hemisphere.

Figure 6c and d, in the northern high latitudes, the cyclone track density and high precipitation do not completely overlapping, why?

Line 153, how to compare the latent and sensible heat fluxes over the Eurasian region?