finding 1.3 : key-message-1-3

Global fossil fuel emissions of CO2 increased at a rate of about 4% per year from 2000 to 2013, when the rate of increase declined to about 2% per year. In 2014, the growth in global fossil fuel emissions further declined to only 1% per year (Olivier et al., 2016). During 2014, the global economy grew by 3%, implying that global emissions became slightly more uncoupled from economic growth, likely a result of greater efficiency and more reliance on less carbon intensive natural gas and renewable energy sources. Emissions were flat in 2015 and 2016 but increased again in 2017 by an estimated 2.0% (high confidence).



This finding is from chapter 1 of Second State of the Carbon Cycle Report (SOCCR2): A Sustained Assessment Report.

Description of evidence base: Quantification of global fossil fuel emissions relies mainly on energy consumption data collected by multiple international organizations such as the International Energy Agency (IEA), the Carbon Dioxide Information Analysis Center (CDIAC), the United Nations (UN), and the Energy Information Administration (EIA). UN energy statistics are used to estimate the amount of CO2 released by gas flaring, and production statistics are used to quantify emissions from cement production. More details on estimation of global fossil fuel emissions are given by Le Quéré et al. (2016) and Ciais et al. (2013).

New information and remaining uncertainties: Uncertainty of global fossil fuel emissions is approximately 5% when expressed as a standard deviation (Le Quéré et al., 2016). This assessment of uncertainties includes the amounts of fuel consumed, the carbon and heat contents of fuels, and the combustion efficiency. Although typically considered as constant in time, the uncertainty expressed as a percentage of total emissions is in reality growing in time, as a higher fraction of total emissions come from emerging economies and developing countries with less sophisticated accounting (Le Quéré et al., 2016; Marland et al., 2009). The majority of the uncertainty is likely to be in the form of systematic errors for individual countries, resulting from biases inherent to their energy statistics and accounting methods (Le Quéré et al., 2016).

Assessment of confidence based on evidence: Energy consumption data clearly show that global fossil fuel emissions have grown over the past decades, with only slight decreases in certain individual years.

Provenance
This finding was derived from figure P.2: P.2. Likelihood and Confidence Evaluation

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