PLEA Network

23 January 2019, Carbon Brief, Climate change’s impact on soil moisture could push land past ‘tipping point’. The impact of climate change on soil moisture could push the land past a “tipping point” – turning it from a net carbon “sink” to a source of CO2, a study finds. The research, published in Nature, shows that levels of soil moisture – which are impacted by rising temperatures and extreme events such as droughts – can have a “large negative influence” on the land’s ability to store carbon. It finds that the rate at which land absorbs carbon is likely to increase until the second half of this century as a result of the “CO2 fertilisation effect” – a phenomenon where increased CO2 levels in the atmosphere bolsters the growth and, therefore, carbon uptake of plants. However, after this point, the fertilisation is expected to “reach a peak”, the lead author tells Carbon Brief. This peak – combined with the negative impact of soil moisture changes – could turn the land “from a carbon sink to a carbon source, greatly accelerating climate change”, she says. The findings represent “a big step forward to show that soil moisture changes play a really important role” in how the land stores carbon, another scientist tells Carbon Brief. Read more here