Complex sentence: Considerable debate exists about the size of the rebound in energy efficiency and the relevance of Jevons paradox to energy conservation; some worry that it may be self-defeating to pursue sustainability through increasing energy efficiency.
Split into simpler sentences: Considerable debate exists about the size of the rebound in energy efficiency and the relevance of Jevons paradox to energy conservation. Some dismiss the paradox, while others worry that it may be self-defeating to pursue sustainability by increasing energy efficiency.