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 →
Anthropogenic carbon emissions have been a large factor in climate change since the start of the industrial revolution. Scientists have become increasingly concerned with warming and other effects associated with the release of carbon into the atmosphere. Currently, most world governments have set a target that limits warming to two degrees Celsius since preindustrial times. With this target in place policies are then enacted to limit carbon emissions and hopefully to mitigate anthropogenic effects on earth’s climate. Steinacher et al. (2013) set out to show that setting a target temperature is not sufficient to control many other effects of climate change such as sea level rise and ocean acidification that also result from anthropogenic carbon emissions. They find that when targets are set for these other factors, the allowable carbon emissions are much lower than current targets based on temperature alone.
Steinacher, M., Joos, F., & Stocker, T. F., 2013. Allowable carbon emissions lowered by multiple climate targets. Nature 499(7457), 197–201. http://goo.gl/iSO7tn