yeah, treeline near 5000m at equator (given rainfall) and sea level in the arctic, so sealevel in the arctic must be the same as 5000m at the equator right
seriously though, earth is an oblate spheroid, atmosphere is a spheroid, so atm. is a tiny bit thinner over the some lattiudes... cold air tends to higher pressure thus increasaing av. air pressure at poles... all these effects are synergistic but the claims I have read by some that Denali without 02s is harder than Everest without 02s, are so much
not saying anyone here is claiming this but claims about elevational differences with latitude tend to be about as reliable as Squamish Chamber of Commerce statistics about the Chief "second largest granite monolith in the world!!!!"