All we have to do is plant trees. Millions of trees, and reduce beef farming.
The desertification of Europe has already started.
It looks like you are more right. Without environmental moisture to capture, the trees are effectively straws depleting ground water and losing it to evaporation.
The Yucatan has enough moisture blowing in that trees aid in capturing moisture and increasing rainfall. Without an outside source of moisture, the false desert forests are likely making things worse water wise.