Australia’s land mass and its vegetation is playing a bigger role than thought in taking carbon dioxide out of the atmosphere.
Over half of the carbon taken up by land in 2011 has been attributed to three Southern Hemisphere semi-arid regions, with the Australian ecosystem being the most influential, international research has found.
A 6% increase in plant cover over Australia since 1981 has quadrupled the sensitivity of Australia’s net carbon uptake to rain.
Semi-arid ecosystems may become increasingly important drivers of inter-annual carbon cycle variability in the future, a report in the journal Nature suggests.
Land and ocean carbon sinks absorb around half of the fossil fuel emissions produced each year, thereby slowing the rise of atmospheric carbon dioxide concentrations.
The new study finds that an unusually large land carbon sink reported in 2011 can be mostly attributed to semi-arid vegetation activity in the Southern Hemisphere.
Benjamin Poulter of Montana State University and colleagues establish that vegetation became greener in Southern Hemisphere semi-arid ecosystems in 2011, which they suggest explains why that year saw the largest uptake of land carbon since atmospheric carbon dioxide measurements began in 1958.
These regions experienced up to six consecutive seasons of increased rainfall and since 1981 a 6% expansion of vegetation cover over Australia quadrupled the sensitivity of continental net carbon uptake to precipitation.
The authors of the study note that as the dynamics of semi-arid ecosystems, which cover 45% of the Earth’s land surface, increase in global importance more research is needed to estimate the contribution of these systems to carbon uptake.