Following are illustrative numbers indicating benefits and costs to Country A of taking specific actions on an international treaty to reduce $\mathrm{CO}_2$ emissions. The choice is either to adhere to the $\mathrm{CO}_2$ emissions cutbacks called for by the treaty or to disregard the treaty.
$$
\begin{array}{lccc}
\hline & \text { Costs } & \text { Benefits } & \text { Net Benefits } \\
\hline \text { All countries adhere to treaty } & 10 & 20 & 10 \\
\begin{array}{l}
\text { No countries adhere to treaty } \\
\begin{array}{l}
\text { Other countries adhere to treaty, } \\
\text { Country A does not }
\end{array}
\end{array} & 0 & -5 & -5 \\
\hline
\end{array}
$$
What is the incentive for Country A to free ride on the abatement efforts of other countries? If all countries become free riders, what is the result?