Monitoring atmospheric composition & climate
MACC-II CO2 flux estimates appear in Nature publication

Carbon32dioxide_small.gifEach year, terrestrial ecosystems take up a significant fraction of anthropogenic CO2 emissions, thereby slowing the increase in greenhouse gases and global warming. In 2011, global land carbon uptake was estimated to be a record breaking 40% of annual fossil fuel and land-cover change CO2 emissions.

Based on a range of datasets and modelling approaches, including the MACC-II CO2 atmospheric inversion, research published last week in Nature demonstrates that enhanced semi-arid ecosystem productivity across the Southern Hemisphere, in particular Australia, explains much of this strong land sink. The emerging role of semi-arid ecosystems on inter-annual global carbon budget dynamics is unexpected and due to a combination of greater than average rainfall in 2010 and 2011 related to a La Niña episode, and also long-term changes in dryland vegetation. These surprising interactions between vegetation-greening trends and climate extremes requires an expansion of ecological research beyond the well-studied tropical and high-latitude biomes to include the emerging role of dryland systems in the Earth system.

The results presented in Nature are especially timely with monthly mean atmospheric CO2 concentrations now reaching unprecedented levels of 400 parts per million in the Northern Hemisphere, as announced earlier this week by the World Meteorological Organization (WMO).