He was instrumental in publishing the Annual Carbon Budget, which draws on a large amount of scientific data to determine the level of imbalance and options for addressing it.
[2] He worked for the Commonwealth Scientific and Industrial Research Organisation before becoming the director of the Australian National University's Climate Change Institute in 2014.
In 2009–2010 he chaired the Expert Working Group on Challenges at the Intersection of Carbon, Energy and Water, reporting to the Prime Minister's Science, Engineering and Innovation Council and the Office of the Chief Scientist of Australia.
In the 1990s, his focus began to shift to global ecosystems when he became a member of the scientific steering committee of the Biospheric Aspects of the Hydrological Cycle core project of the IGBP (International Geosphere-Biosphere Programme).
His research contributed to addressing that question, through his work on turbulent fluxes near the land surface, boundary-layer budgeting and quantifying the water balance at broader scales.