I can't help wondering if their consideration of climate change as a covariate factor has been rigorous enough.

Climate change is happening everywhere but it is quite noticeable in Japan with summers getting hotter and winters getting milder.

California and North Carolina too. Back when I lived in Socal; we would have at two weeks of heavy rain during April-May with flooding. Now it's only a few days of lighter rain. The air used to be very dry since it would be so cold. Now it is becoming more humid before I left.

Raleigh used to have more snowy winters from what I was told. Now a days winters have a 1 in 4 chance of giving snow you might see in the morning for most of the area.