Bertler then moved to New Zealand to commence her PhD in geology at the Victoria University of Wellington under the supervision of Peter Barrett, then director of the Antarctic Research Centre.

During her PhD Nancy established collaborations with international partners in Germany and the US and initiated New Zealand's ice core research capability in the Ross Sea.

Peter Barrett, Tim Naish, Alex Malahoff, Bertler went on to establish major infrastructure in support of ice core research in New Zealand.

Since her joint appointment with Victoria University of Wellington and GNS Science in 2004, Bertler has led and managed the National Ice Core Research Programme.

[1] Bertler was awarded a Rutherford Discovery Fellowship in 2011[4] and is Chief Scientist and Field Leader of Roosevelt Island Climate Evolution Programme (RICE), 9 nation ice core drilling project (NZ, USA, Denmark, Germany, United Kingdom, Italy, Australia, China, Sweden).