by Makari Krause

With climate change proceeding full-bore, questions are continuously raised about how the carbon cycle will react and whether climate change will be a negative or positive feedback loop. As atmospheric CO­₂ concentrations increase, most scientists agree that the rate of photosynthesis will increase leading to an increase in stored carbon. This same increase in atmospheric CO­₂, however, will increase soil respiration, releasing additional CO­₂ into the atmosphere. The balance between these two effects is crucial in determining what the net effect of increasing atmospheric CO­₂ will be on the carbon cycle. Cox et al. (2013) use a number of different models to identify a linear relationship between the sensitivity of tropical land carbon storage to warming and the sensitivity of the annual growth rate of atmospheric CO­₂ to tropical temperature anomalies. The study focuses on land between latitudes 30˚ north and 30˚ south; their established linear relationship estimates that in this area warming will release 53±17 gigatonnes of carbon per Kelvin. While this sounds like a staggering amount, it is much lower than current estimates and suggests that tropical forests will not experience as much warming-induced dieback as was previously thought. Continue reading →