On: The USDA's gardening zones shifted, this map shows...

[smolder]

Yes, it is. Percentages don't mean anything in temperature unless it is Kelvin where 0 is truly 0.

1 to 4 degrees Celsius is not a 300% increase in anything but the integer representing temp. Try that in Fahrenheit or with a negative value.

Edit: I think I initially missed your point that percentages are kind of silly to use anyway.

[dragonwriter → smolder]

> Percentages don’t mean anything in temperature unless it is Kelvin where 0 is truly 0.

Well, technically any absolute scale: Kelvin is the most common, but Rankine has the same feature. (It just uses Fahrenheit-sized degrees instead of Celsius-sized.)

[smolder → dragonwriter]

I wondered if there might be others but left it up to you to correct me. :)