Complex sentence: Some scientific bodies have recommended specific policies to governments and science can play a role in informing an effective response to climate change, however, policy decisions may require value judgements and so are not included in the scientific opinion.
Split into simpler sentences: Some scientific bodies have recommended specific policies to governments and science can play a role in informing an effective response to climate change. Policy decisions, however, may require value judgements and so are not included in the scientific opinion.