Climate change is one of the most pressing challenges of our times: rising temperatures lead to an increase of natural hazards, such as prolonged droughts and wildfires, but also more floods and heavy rain falls. In the last IPCC report from 2023, it is mentioned that the goal of the Paris agreement to keep temperature rise to 1.5 degree Celsius is out of sight. It is, nevertheless, important that people are supported in successfully change their behaviour, and to show policy makers ways to speed up the sustainability transition and minimise the impact of climate change.

In the present talk, I will present three studies in which we investigated the effect of defaults on cognitions and behaviours related to ecological sustainability. First, focussing on e-commerce, we investigated (a) whether nudging could help consumers shift towards pick-up point delivery as a more sustainable choice, and (b) which type of nudging would be most effective. Second, I present two studies exploring whether vegetarian nudges can lead to more sustainable food choices in an online setting (study 1) and a cafeteria (study 2). Together, this work shows the huge potential defaults and different types of nudges can have to foster sustainable behaviour, and demonstrate the usefulness in our efforts to support societal change.