Explain why scientists believe that warm climates provide greater biodiversit

because they do and they feel like it

Warm climate can be called a tropical climate.
because in warm climates it is a temperature that is suitable for living and developing plants so it is not surprising if in warm climates many biodiversity grows ..
Or also you can put Warm climates allow for a year-round growing season. Plants are more available as a food resource, which can support more organisms. Hope this helps :))