Blurring evidence with advocacy: a systematic review of policy recommendations for net zero.

Policy recommendations (PRs) now play a crucial role in tackling the climate crisis, underscoring the need for evidence-based, objective and transparent communication. Scientific studies often put forward PRs, but their quality has not yet been evaluated. Here, we systematically appraised the quality of PRs in areas of green energy and transportation for tackling climate change. Four databases were searched from 2019. Over three thousand papers were considered, and 23 studies are included. Quality rating, based on the Evidence Communication Rules for Policy (ECR-P) critical appraisal tool, indicated poor quality in PRs across all studies. There was a clear trend towards advocacy as opposed to providing neutral information, further exacerbated by inadequate disclosure of uncertainties. Communication quality was markedly better regarding study findings and conclusions compared to PRs. Researchers should use the same scientific rigour and reporting standards in PRs as in any other aspect of their research. A reporting guideline for scientific-based PRs could greatly assist in this area, elevating the standards of communication for both academic publishing and global policymaking while reducing potential criticism that scientists simply put forward their own opinions.