The desert areas should be considered for what will remain, after the shift, as much as for any other factor. Scorpions, lack of vegetation roots to grow into brush, and rock hard soil. Unless one is planning to live off supplies forever, consider where you place your camp! Desert areas with hard baked soil and scarse water should not be expected to support a large population reliant upon gardening.
Note N America Deserts commentary.
Note Arizona Lava Flows commentary.