EPRU Researchers contribute to major international study identifying “a private solution trap” in collective global challenges like climate change.

Researchers from the Environmental Policy Research Unit (EPRU) at the University of Cape Town (UCT), Professor Martine Visser and Max Baard, contributed to a new international study, published in Proceedings of the National Academy of Sciences (PNAS), that finds a consistent pattern in collective action problems such as climate change. When wealthier actors have the option to protect themselves through private solutions, they tend to invest less in public solutions that protect everyone, with the result that inequality grows and many are left exposed.

The study, led by the University of Nottingham and conducted by an international team of 72 economists and psychologists, invited 7,504 participants across 34 countries to take part in a collective action game. In small groups, participants could allocate resources to a public solution that benefits everyone, or a private solution that benefits only themselves. The setup captures a real policy dilemma, where governments can invest in global emissions reductions (a public solution) or focus on local adaptation and protection (a private solution).

Across all 34 countries, participants given higher budgets adopted private solutions far more often than those given lower budgets and contributed proportionally less to public solutions. This dynamic increased inequality within groups over the course of the game and often left lower budget participants unprotected when public solutions were not provided.

Dr Eugene Malthouse, Research Fellow at the University of Nottingham and corresponding author, said: “Our results highlight the potential consequences of the private solution trap whereby the existence and widespread adoption of private solutions undermine the provision of public solutions, while also increasing wealth inequality and leaving less-wealthy individuals and nations unprotected against collective risks.” 

The researchers also found that cultural values help explain cross-country differences in the balance between private and public investment. Countries where harmony with the natural world is more strongly emphasised were more likely to invest in public solutions, while countries with stronger hierarchy-oriented values tended to show higher private solution adoption. At the same time, two behavioural patterns supported public solutions across contexts. Groups were more likely to succeed when early contributions to the public solution were higher, and when participants reciprocated one another’s contributions over time.

EPRU and UCT played a vital role in the South African implementation of the study. Prof Visser and Max Baard secured local funding, obtained required ethics and institutional approvals, and supported survey material adaptation for the South African context in line with the projects harmonisation approach. Baard then ran the experimental sessions at UCT with 240 student participants over two days. The South African results align with the broader international pattern, reinforcing that the private solution trap can emerge across very different national settings.

While the primary focus of the study was on climate change, these findings are applicable to any collective problem where there are both public and private solutions, such as education, healthcare or security. 

The study was jointly funded by the University of Warwick’s Global Research Priorities, the European Research Council, the Spanish Ministry of Science and Innovation, and local universities within the participating countries. 

More information is available from Dr Eugene Malthouse in the School of Economics, via eugene.malthouse@nottingham.ac.uk; or Liz Goodwin, Media Relations Manager for the Faculty of Arts and Social Sciences, via liz.goodwin@nottingham.ac.uk or 0115 748 5133.