  Climate change is an ongoing topic in nearly all areas of society since many
years. A discussion of climate change without referring to scientific results
is not imaginable. This is especially the case for policies since action on the
macro scale is required to avoid costly consequences for society. In this
study, we deal with the question of how research on climate change and policy
are connected. In 2019, the new Overton database of policy documents was
released including links to research papers that are cited by policy documents.
The use of results and recommendations from research on climate change might be
reflected in citations of scientific papers in policy documents. Although we
suspect a lot of uncertainty related to the coverage of policy documents in
Overton, there seems to be an impact of international climate policy cycles on
policy document publication. We observe local peaks in climate policy documents
around major decisions in international climate diplomacy. Our results point
out that IGOs and think tanks -- with a focus on climate change -- have
published more climate change policy documents than expected. We found that
climate change papers that are cited in climate change policy documents
received significantly more citations on average than climate change papers
that are not cited in these documents. Both areas of society (science and
policy) focus on similar climate change research fields: biology, earth
sciences, engineering, and disease sciences. Based on these and other empirical
results in this study, we propose a simple model of policy impact considering a
chain of different document types: the chain starts with scientific assessment
reports (systematic reviews) that lead via science communication documents
(policy briefs, policy reports or plain language summaries) and government
reports to legislative documents.
