In E2, which MUST be confirmed with Ctrl+Shift+Enter:

=SQRT(MIN(((D2 - $A$2:$A$722)^2 + (C2 - $B$2:$B$722)^2)))

Copy down.

That gives some numbers like this:

        --A-- --B-- --C-- --D-- --E--
  335   0.363 16.65 3.996 2.121 0.217
  336   0.355 16.70 4.007 2.119 0.216
  337   0.348 16.75 4.019 2.118 0.216
  338   0.339 16.80 4.030 2.116 0.216
  339   0.331 16.85 4.041 2.114 0.217
  340   0.324 16.90 4.053 2.112 0.217
  341   0.316 16.95 4.064 2.111 0.216
  342   0.308 17.00 4.075 2.109 0.216
  343   0.299 17.05 4.086 2.107 0.217
  344   0.292 17.10 4.098 2.105 0.218
  345   0.286 17.15 4.109 2.104 0.218
  346   0.277 17.20 4.120 2.102 0.218