I don't see any problem with plotting or loading this data.
Indeed the first line is a string instead of a number and many numbers of which you want to take the Log are 0 but in general mathematica doesn't realy care about that at all.
In[88]:= alist = Import["CO2_IR_50.csv", "Data"];
In[102]:= cross = alist[[All, 2]];
logC = Log[cross];
logC[[1 ;; 10]]
Out[104]= {Log[
"cross_section"], Indeterminate, Indeterminate, Indeterminate, \
Indeterminate, Indeterminate, Indeterminate, Indeterminate, \
Indeterminate, Indeterminate}
Even plotting work ok, it just ignores values it cannot plot.
ListPlot[data]
ListPlot[Transpose[{alist[[All, 1]], logC}]]
PS use a semicolon at the end of your lines to prevent mathematica printing everything to the notebook when it is not needed.
