Nestled among the dry eucalypt forests behind Nagambie, north of Melbourne, the 36-metre metal ''flux tower'' looks out of place.
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The tower sends out an infrared beam that, 20 times a second, measures the transfer of carbon dioxide between the atmosphere and the landscape. The project is part of efforts to better understand one of the big unknown questions in climate science: will soil, trees and plants continue to soak up large amounts of carbon dioxide as the planet warms?
Readings from flux towers are one of many sources of data that help shape scientists' understanding of the climate. The latest understanding will become clearer with the release of a major report by the United Nations' Intergovernmental Panel on Climate Change on Friday.
While the towers are monitoring present day conditions, at one site near Sydney native trees are being doused with high levels of CO2 via giant metal rings to simulate the future impact of dangerously high atmospheric concentrations of greenhouse gases.
David Ellsworth, from the University of Western Sydney, said the project was key to understanding whether fertilisation would continue if emissions reached high concentrations, or whether trees would reach CO2 saturation.
Monash University researcher Ian McHugh said the cycling of CO2 between landscapes and the atmosphere was complex and not well understood, but critical.
CSIRO estimates the landscape soaked up a third of the CO2 emitted from burning fossil fuels in Australia over the past two decades. In wet years trees and plants tend to draw in huge amounts of CO2 as they grow. Roughly the same amount is expelled in dry years as they wither or burn.
Mr McHugh said Australian ecosystems were taking in a little more greenhouse gas than they send out - in part because previously cleared vegetation is growing back, but also because extra CO2 in the atmosphere is making plants grow faster and larger.
But as the planet warms further and rainfall becomes less reliable, landscapes could become less efficient emissions sinks, and vegetation might reach CO2 saturation.
CSIRO terrestrial carbon expert Pep Canadell said over time the data on how the landscape absorbs CO2 would improve and be fed into models, giving a better projection of what emissions cuts would give the best chance of keeping warming to relatively safe levels.
