Its study into environmental, social and governance (ESG) priorities found that employee activism is a key driver for achieving goals in these areas, with 86% of HR directors believing staff to have an influential role.
The findings follow another survey published in The Times in January, which found that four in 10 believe ESG change lies with employees rather than executives or investors.
Customers are the main influencer for integrating sustainability into corporate activities, Mercer found: 93% of HR directors in the UK thought this was the case, compared to 87% across Europe.
More than three-quarters (77%) felt shareholders had a significant influence on ESG activities, and 64% felt politics was driving more investment in this area.
