Emissions of CO₂ from fossil fuels and industry did not change from 2014 to 2016, yet there was a record increase in CO₂ concentration in the atmosphere. This apparent inconsistency is explained by the response of the natural carbon cycle to the 2015–2016 El Niño event, but it raises important questions about our ability to detect a sustained change in emissions from the atmospheric record. High-accuracy calibrated atmospheric measurements, diverse satellite data, and integrative modelling approaches could, and ultimately must, provide independent evidence of the effectiveness of collective action to address climate change. This verification will only be possible if we can fully filter out the background variability in atmospheric CO₂ concentrations driven by natural processes, a challenge that still escapes us.

… Now that we see signs of a sustained change in emission trajectory away from the high growth rates of the first decade of this millennium, independent verification of global emissions takes on a new imperative. Providing independent verification in the context of the Paris Agreement, with its global stocktake every five years, leads to a new urgency for the scientific community to focus on reducing key uncertainties and quantifying natural variability in all components of the carbon cycle so that it can collectively meet the demands of policymakers and society.

—Peters et al.

The data point to China as the main cause of the renewed growth in fossil emissions, with a projected growth of 3.5%. CO₂ emissions are expected to decline by 0.4% in the US and 0.2% in the EU, smaller declines than during the previous decade. Increases in coal use in China and the US are expected this year, reversing their decreases since 2013.

Some had previously hoped that emissions might soon reach their peak after three stable years. The GCP comment is published in the journal Nature Climate Change, as well as in Earth System Science Data Discussions and Environmental Research Letters.

Other key findings are that CO₂ emissions decreased in the presence of growing economic activity in 22 countries, representing 20% of global emissions. Renewable energy has also increased rapidly at 14% per year over the last five years—albeit from a very low base.

Resources

• Glen P. Peters, Corinne Le Quéré, Robbie M. Andrew, Josep G. Canadell, Pierre Friedlingstein, Tatiana Ilyina, Robert B. Jackson, Fortunat Joos, Jan Ivar Korsbakken, Galen A. McKinley, Stephen Sitch & Pieter Tans (2017) “Towards real-time verification of CO₂ emissions” Nature Climate Change doi: 10.1038/s41558-017-0013-9