Nielsen enthusiastically advocated for a comprehensive repository of data on species and their characteristics, recognising informatics as a key to understanding and managing biodiversity. During the 1990s, he and other scientists pushed for an extensive global biodiversity resource, designed to utilise up-to-date informatics software and capable of collating data held on various separate databases. In 1999, the Organisation for Economic Co-operation and Development endorsed a proposal for the establishment of 'a global biodiversity information facility',FINAL REPORT OF THE OECD MEGASCIENCE FORUM WORKING GROUP ON BIOLOGICAL INFORMATICS, January, 1999 and on 1 March 2001, the Global Biodiversity Information Facility was officially launched. As Australia's Head of Delegation for the GBIF and a founding member, Nielsen was en route to Montreal to attend the first meeting of the governing board when he died of a heart attack.
