How can causal loop diagrams help us make sense of complex issues?

At the Plastic Waste Innovation Hub we often say that we use system thinking and systems approaches, but you might be wondering what do we really mean by that? According to Donella Meadows systems thinking is a way of understanding the world that focuses on the interconnections and feedback loops within systems, rather than just isolated events. 

We worked with artist Luke Demarest and Wellcome Trust Fellow at UCL's Institute for Global Health Dr. Alys McAlpine to create a simple causal loop diagram that explores the interconnections and feedback loops between nappy/diaper plastic waste, pollution, health, economic impacts and policy guidance. A causal loop is a concept from systems thinking that represents how different variables in a system influence each other through feedback. 

We start by describing the current state of the system where we have delayed toilet training start and end age leading to high nappy/diaper use which in turn leads to higher waste, pollution and costs associated with waste disposal and health care.

We then look at how feedback loops from increased clarity and evidence use in UK toilet training guidance by the NHS can create feedback loops within the system.

We observe the interconnections between health and education guidance and the impact those could have to decrease toilet training start and end ages leading to reduction of waste and costs and increase in health outcomes.

Watch Professor Mark Miodownik explain the interconnections in this short video. Image below by James Gifford-Mead of Prof. Miodownik with MP Caroline Voaden during Evidence Week 2025.

Or have a play yourself by visiting https://demare.st/evidence-week/