I was looking into the code which is used to apply Knutson's criteria to generate future TC event sets and I stumbled upon something that I find very weird (a bug I would say).

Knutson's work provides change in frequency and in intensity for each TC category and basin. These changes are however inherently related to each other as they, in the end, aim to describe shifts in frequency curves from two different standpoints:

• Intensity: how does the curve shift up or down.
• Frequency: how does the curve shift left or right.
  In reality, the curve is shifted and you can describe this shift as one of the above. For instance, increasing intensity by 10% will imply that some category 4 storms will become category 5. This indirectly will hence also change the frequency of each category (in this case, increasing cat5 storms frequency and decreasing cat4 storms; of course cat4 storms frequency might still increase due to some of the cat3 storms becoming cat4 after applying the intensity change).

In the code, changes in frequency and in intensity are BOTH applied. This is fundamentally wrong.

For the avoidance of doubt, I made a quick search and stumble upon this paper, which also describes this feature of Knutson's analysis:
https://rmets.onlinelibrary.wiley.com/doi/epdf/10.1002/qj.4299
This also provides some recommendation on the application of Knutson's change estimates.

I think that anyway the application of the Knutson's criteria need to be revised at some point (Knutson 2015 is kind of outdated and the same author published more recent and comprehensive estimates), but in the meantime at least this clear bug should be fixed in my opinion.

I am not sure who in CLIMADA's community is using or working with climate change for TC though.