Emacs text-scale-adjust causes line numbers column to incrementally shrink and disappear

Here is a workaround. It works on my emacs 23.1.1. This same question came up again (months later), and I'd learnt a bit about elisp in the mean time, so I had a go at it. See the following link for my answer there. Font size issues with Emacs in linum-mode.

The easiest, most straightforward solution I've seen just to set the line numbers to a fixed height. This can be accomplished easily, in accordance with user78810's answer: Font size issues with Emacs in linum-mode

To wit, add the following line in your emacs config (or to your dotspacemacs/user-config function, if you're spacing out evil style):

(eval-after-load "linum"
  '(set-face-attribute 'linum nil :height 100))