How will climate change influence phosphorus systems? An expert elicitation approach.

Phosphorus (P) sustainability is a "wicked problem," due to complex environmental and societal challenges. This will be further exacerbated by climate change, although interdisciplinary evidence on effects and adaptation are lacking. Our knowledge of how climate change may impact agricultural-systems P dynamics is challenged by our understanding of baseline versus managed system responses, complex biophysical and societal process interactions, and thresholds. This challenge was discussed at the 10th International P Workshop, gathering academia and industry experts. This perspective paper shows this community's current state of knowledge and understanding on the impacts of climate change on P across soils, waters, and humans within agricultural systems. Participants discussed topic knowledge and data availability, and positioned their responses on a matrix with importance (relevance of the impact according to their understanding and knowledge) and confidence (about the data availability regarding that impact) as axes. The 320 statements were digitized and categorized into themes, reported here in the context of contemporary literature. While we do not address all topics across agriculture, our analysis highlights the community's developing state of knowledge on connections between P systems and climate. Although the depth of topic-specific knowledge varied greatly, this analysis emphasizes that P must become more visible in climate change discourse and addressed by establishing transdisciplinary relationships. We recommend further data collection regarding circular economy and climate adaptation, and modeling and policy development to anticipate risks and support adaptive P management, including attention to thresholds and socioeconomic linkages, where consequences of inaction may be abrupt and widespread.