Observations from Orbit
NASA's Orbiting Carbon Observatory (OCO) has reported that carbon dioxide levels spiked during its observation period of 2015 to 2016. It's thought that this fluctuation comes as a result of the major El Niño event that took place in that time frame.
The data correlated the increase with the effect of heat and drought on tropical forests. As a result of these conditions, forests were less able to take up carbon dioxide and turn it into oxygen.
"If future climate is more like this recent El Niño, the trouble is the Earth may actually lose some of the carbon removal services we get from these tropical forests, and then CO2 will increase even faster in the atmosphere," said OCO science team member Scott Dennin, according to a report from the BBC.
In a normal year, the concentration of carbon dioxide in the atmosphere increases by two parts per million by volume (ppmv) of molecules in the air. During this El Niño period, it rose by three ppmv, the equivalent of six gigatonnes of the gas.
The 2015-16 El Niño brought widespread weather changes that boosted carbon dioxide levels. In South America, it was widespread drought, which impeded plant life's ability to consume the gas. In Africa, above-average temperatures meant that carbon dioxide was released into the atmosphere as dead plant material decomposed. Meanwhile, conditions in Asia meant that wildfires ran rampant, burning peat carbon that had built up over thousands of years.
The El Niño/La Niña oscillation is a natural climate cycle on Earth, and these environmental contributors likely couldn't have been prevented. However, this shouldn't downplay the human component in rising carbon dioxide levels on earth; everything from the production of cement to the use of fossil fuels contributes to the amount of carbon dioxide in the atmosphere. Additionally, some research has suggested that climate change and rising greenhouse gas levels are making El Niño events more intense, contributing to a rather vicious cycle.
These findings demonstrate that we can't rely on the ability of Earth's vegetation to counteract our carbon dioxide production. And as climate change rolls forward, it will be important that we continue to monitor CO2 levels closely.
While the OCO is a valuable tool to scientists, its scope is rather narrow. It's capable of taking very accurate readings, but can only look at a 10 kilometer tract of land as it floats above the planet. The European Space Agency plans to deploy a set of satellites known as Sentinel-7 to provide similarly precise measurements that can span a much wider area. These instruments could allow authorities to check in on the carbon emissions of individual countries.