Halvorsen is Director of the Center for International Climate and Environmental Research, based in Oslo, Norway. Sheis also head of Bioteknologirådet and chairman of the board for the Natural History Museum.

Halvorsen is a former politician and was a member of the Norwegian government between 2005 and 2013. From 2005 to 2009 she was Norway’s first female Minister of Finance, and from 2009 to 2013 she was Minister of Education and Research. From 2005 to 2012 she served as deputy prime minister. 

She was elected Member of Parliament in 1989 and was leader of the Socialist Left Party from 1997 to 2012. From 1989 to 2005 she was a member of the Standing Committees on Finance and Economic Affairs, Scrutiny and Constitutional Affairs, and Foreign Affairs and Defence. She was Parliamentary leader for the Socialist Left Party from 1997 to 2005. 

Halvorsen has published two books: “Gjennomslag” (2012) co-authored with Lilla Sølhusvik and “Rett fra hjertet” (2004) co-authored with with Ingolf Håkon Teigene.