Methods
We used an iterative process to develop the alternate futures for our
Grand Challenge. For full details of the methods please see Nash et al.
(in review). Here, we provide methods specific to our challenge. We
identified 70 drivers, which were initially grouped into 12 umbrella
drivers (Extended Data 1). To select drivers for incorporation into the
alternate futures narratives, all authors were asked to evaluate each
umbrella driver with respect to importance to the challenge and
potential for society to influence the behaviour of the umbrella driver.
A discussion of the results of this exercise highlighted that only those
umbrella drivers that were directly linked to both human and ocean
health had been selected as important with respect to the impact of the
umbrella driver on the challenge. For example, ‘innovations in human
health’ was considered to have a moderate to important impact on human
health but was not perceived to have an important impact on ocean
health. As a result, this umbrella driver only had a low to moderately
important impact on the challenge overall. This result revealed a
potential weakness of this step in the process, as it didn’t explicitly
account for the indirect interactions arising from feedbacks between
human and ocean health. As a consequence, we refined the umbrella
drivers to an updated list of 5 umbrella drivers (in the main text, just
termed ‘drivers’) for use in developing the alternate futures: (1)
Worldview, decision-making context and approach to behaviour change; (2)
Power and agency; (3) Human development and industry; (4) Food system;
and (5) Lifestyle and connectedness to the oceans. We explored the
potential trajectories of these drivers from Business-as-Usual to
pathways that were more in line with the SDGs. Using published research
relevant to each driver, we identified a series of descriptors of the
drivers under the two 2030 scenarios (Table S1), based on likely and
possible trajectories for the drivers. It should be noted that these
drivers are not mutually exclusive, and overlap in many ways, as shown
in the section on ‘Exploring the drivers that influence these alternate
futures’.