Global carbon budget 2014

Accurate assessment of anthropogenic carbon dioxide (CO2)emissions and their redistribution among the atmosphere, ocean, andterrestrial biosphere is important to better understand the globalcarbon cycle, support the development of climate policies, and projectfuture climate change. Here we describe datasets and a methodology toquantify all major components of the global carbon budget, includingtheir uncertainties, based on the combination of a range of data,algorithms, statistics and model estimates and their interpretation by abroad scientific community. We discuss changes compared to previousestimates, consistency within and among components, alongsidemethodology and data limitations. CO2 emissions from fossilfuel combustion and cement production (EFF) are based onenergy statistics and cement production data, respectively, whileemissions from Land-Use Change (ELUC), mainly deforestation,are based on combined evidence from land-cover change data, fireactivity associated with deforestation, and models. The globalatmospheric CO2 concentration is measured directly and itsrate of growth (GATM) is computed from the annual changes inconcentration. The mean ocean CO2 sink (SOCEAN) isbased on observations from the 1990s, while the annual anomalies andtrends are estimated with ocean models. The variability inSOCEAN is evaluated with data products based on surveys ofocean CO2 measurements. The global residual terrestrialCO2 sink (SLAND) is estimated by the difference ofthe other terms of the global carbon budget and compared to results ofindependent Dynamic Global Vegetation Models forced by observed climate,CO2 and land cover change (some including nitrogen-carboninteractions). We compare the variability and mean land and ocean fluxesto estimates from three atmospheric inverse methods for three broadlatitude bands. All uncertainties are reported as ±1σ,reflecting the current capacity to characterise the annual estimates ofeach component of the global carbon budget. For the last decadeavailable (2004-2013), EFF was 8.9 ± 0.4 GtCyr-1, ELUC 0.9 ± 0.5 GtC yr-1,GATM 4.3 ± 0.1 GtC yr-1, SOCEAN2.6 ± 0.5 GtC yr-1, and SLAND 2.9 ±0.8 GtC yr-1. For year 2013 alone, EFF grew to 9.9± 0.5 GtC yr-1, 2.3% above 2012, contining the growthtrend in these emissions. ELUC was 0.9 ± 0.5 GtCyr-1, GATM was 5.4 ± 0.2 GtCyr-1, SOCEAN was 2.9 ± 0.5 GtCyr-1 and SLAND was 2.5 ± 0.9 GtCyr-1. GATM was high in 2013 reflecting a steadyincrease in EFF and smaller and opposite changes betweenSOCEAN and SLAND compared to the past decade(2004-2013). The global atmospheric CO2 concentration reached395.31 ± 0.10 ppm averaged over 2013. We estimate thatEFF will increase by 2.5% (1.3-3.5%) to 10.1 ± 0.6 GtCin 2014 (37.0 ± 2.2 GtCO2 yr-1), 65% aboveemissions in 1990, based on projections of World Gross Domestic Productand recent changes in the carbon intensity of the economy. From thisprojection of EFF and assumed constant ELUC for2014, cumulative emissions of CO2 will reach about 545± 55 GtC (2000 ± 200 GtCO2) for 1870-2014,about 75% from EFF and 25% from ELUC. This paperdocuments changes in the methods and datasets used in this new carbonbudget compared with previous publications of this living dataset (LeQuéré et al., 2013, 2014). All observations presented herecan be downloaded from the Carbon Dioxide Information Analysis Center(doi:10.3334/CDIAC/GCP_2014). Italic font highlights significant methodological changesand results compared to the Le Quéré et al. (2015)manuscript that accompanies the previous version of this living data.