An overly centralized economy, not the changes in the climate, is responsible for the poor agricultural production in Country X since its new government came to power. Neighboring Country Y has experienced the same climatic conditions, but while agricultural production has been falling in Country X, it has been rising in Country Y.
The statement 'The crops that have always been grown in Country X are different from those that have always been grown in Country Y' would most weaken the argument above.