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Global Carbon Budget
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Carbon dioxide (CO2) emissions from fossil fuel burning and cement production increased by 2.1% in 2012, with a total of 9.7±0.5 GtC (billion tonnes of carbon) emitted to the atmosphere, 58% above 1990 emissions (the Kyoto Protocol reference year). Emissions are projected to increase by a further 2.1% in 2013. In 2012, the ocean and land carbon sinks respectively removed 28% and 23% of total (fossil fuel and land use change) CO2. The land sink in 2012 was much less than in 2011, a year of a strong La Niña weather pattern.

coal mine

Emissions from fossil fuels and cement

Carbon dioxide (CO2) emissions from fossil fuel burning and cement production increased by 2.1% in 2012, with a total of 9.7±0.5 GtC emitted to the atmosphere. These emissions were the highest in human history and 58% higher than in 1990 (the Kyoto Protocol reference year). In 2012, coal burning was responsible for 43% of the total emissions, oil 33%, gas 18%, cement 5.3%, and gas flaring 0.6%. Emissions are projected to increase by 2.1% in 2013, to a record high of 9.9±0.5 GtC (36 billion tonnes of CO2), 61% above emissions in 1990.

Uncertainty of the global fossil fuel CO2 is estimated at ±5% (±1 sigma bounds based on the 10% at ±2 sigma bounds published by Andres et al. 2012).

The growth of the global Gross Domestic Product (GDP) for 2012 was 3.2%. The fossil fuel carbon intensity of the economy declined (improved) by -1.0%yr-1. The 2013 projection of 2.1% growth is based on the world GDP projection of 2.9% made by the International Monetary Fund and our estimate of improvements in the fossil intensity of the economy of -0.8%.

CO2 emissions from fossil fuel and other industrial processes are calculated by the Carbon Dioxide Information Analysis Center of the US Oak Ridge National Laboratory. For the period 1959 to 2010 the calculations were based on United Nations Energy Statistics and cement data from the US Geological Survey. For the years 2011 and 2012, the calculations are preliminary and based on BP energy data. Uncertainty of emissions from individual countries can be significantly larger than the global uncertainty.

world showing Asia

Regional fossil fuel emissions

In 2012, global CO2 emissions were dominated by emissions from China (27%), the USA (14%), the EU (28 member states; 10%) and India (6%). Growth rates of these countries from 2011 to 2012 were 5.9% for China, −3.7% for the USA, −1.3% for the EU28, and 7.7% for India. The per-capita CO2 emissions in 2012 were 1.4 tC person-1 yr-1 for the globe, and 4.4, 1.9, 1.9 and 0.5 tonnes of C person-1 yr-1 for the USA, the EU, China, and India, respectively.

The countries contributing most to the 2012 change in emissions were China (71% increase), USA (26% decrease), India (21% increase), and Japan (11% increase).

In 1990, 62% of global emissions were emitted in Annex B countries (developed countries), 34% in non-Annex B (developing countries), and 4% in bunker fuels used for international shipping and aviation. In 2012, 37% of emissions were emitted in Annex B countries, and 57% in non-Annex B countries.

cargo ship

Consumption-based fossil fuel emissions

Consumption-based emissions allocate emissions to where goods and services are consumed, not where they are produced and emissions released. Territorial-based emissions in Annex B (developed countries) countries remained stable from 1990-2011, while consumption-based emissions grew at 0.5% yr-1. In non-Annex B countries, territorial- and consumption-based emissions grew at 4.3% yr-1 and 4.0% yr-1, respectively.

This accounting framework addresses the growing outsourcing of CO2 emissions by countries that consume goods manufactured elsewhere.

The difference between territorial-based and consumption-based emissions (the net emission transfer via international trade) from non-Annex B to Annex B countries has increased from 0.05 GtC yr-1 in 1990 to 0.46 GtC in 2011, with an average annual growth rate of 12% yr-1.

In 2011 (the latest year with consumption data), the biggest emitters from a consumption-based perspective were China (22% of the global total), USA (17%), EU (14%), and India (5%).

ocean waves

Emissions from land use change

CO2 emissions from deforestation and other land use change were 0.9±0.5 GtC on average during 2003-2012, accounting for about 8% of all emissions from human activity (fossil fuel, cement, land use change). The data suggest an overall decrease trend in land use change emissions particularly since 2000. Emissions were 1.4±0.5 GtC yr-1 during the decade of 1990s.

The implementation of new land policies, higher law enforcement to stop illegal deforestation, and new afforestation and regrowth of previously deforested areas could all have contributed to the decline since 2000. The uncertainty for all land use change emission estimates remains large. CO2 emissions from land use change are mainly based on forest statistics of the Food and Agriculture Organization and a bookkeeping method by Houghton, updated to also include emissions from peat fires.


Emission pathways

Current trajectories of fossil fuel emissions are tracking some of the most carbon intensive emission scenarios used in the Intergovernmental Panel on Climate Change (IPCC). The current trajectory is tracking the Representative Concentration Pathway 8.5 (of the latest family of IPCC scenarios) that takes the planet's average temperature to about 3.2°C to 5.4°C above pre-industrial times by 2100.

Long-term scenarios of emissions or atmospheric concentrations are designed to represent a range of plausible future trajectories as input for climate change research. The IPCC process has resulted in four generations of emissions scenarios: Scientific Assessment 1990 (SA90), IPCC Scenarios 1992 (IS92), Special Report on Emissions Scenarios (SRES), and the evolving Representative Concentration Pathways (RCPs) used in the IPCC Fifth Assessment Report (2013-2014).

ocean waves

CO2 removals by natural sinks

Of the total emissions from human activities during the period 2003-2012, about 45% accumulated in the atmosphere, 27% in the ocean and 27% on land. During this period, the size of the natural sinks has grown in response to the increasing emissions, although year-to-year variability of that growth is large.

The ocean sink is estimated by using observations for the period 1990-2000, and an ensemble of six global ocean biogeochemistry models for the trend and variaiblity. The models were normalized to the observed mean ocean sinks for the 1990s. Models were forced with meteorological data from the US national Centers for Environmental Prediction and atmospheric CO2 concentration. In 2012 the ocean sink is estimated to have removed 28% of total (fossil fuel plus net land use change) CO2 emissions, similar to the 1959-2012 aggregate ocean sink fraction (27%).

The land sink is calculated as the residual of the sum of all sources minus the sum of the atmosphere and ocean sinks. An independent estimate of the consistency of the residual land sink is obtained by estimating the land sink from eight dynamic global vegetation models.

In 2012 the land sink is estimated to have removed 23% of total (fossil fuel plus net land use change) CO2 emissions, much lower than the very high land sink fraction in 2011 (39%). The 2012 and 2011 land sink fractions fall on either side of the 1959-2012 aggregate land sink fraction (28%). The high land sink in 2011 was associated with a La Niña weather pattern, and contributed to slower than typical increases in atmospheric CO2. This temporarily high sink abated in 2012, helping to explain the higher CO2 growth in 2012.

Sky & clouds

Atmospheric CO2

The annual growth rate of atmospheric CO2 was 5.2±0.2 GtC in 2012, corresponding to an increase of 2.43±0.09 parts per million in the atmospheric concentration. This is significantly above the 2003-2012 average of 4.3±0.1 GtC yr-1, thought the interannual variability in atmospheric growth rate is large. The global atmospheric CO2 concentration reached 392.52±0.10 ppm on average over 2012.

The rates of atmospheric CO2 accumulation are influenced by both the anthropogenic emissions and the net uptake by natural sinks (ocean and land), and their interannual variability is large.

The atmospheric CO2 concentration in 2012 was 42% above the concentration at the start of the Industrial Revolution (about 278 ppm in 1750). The present CO2 concentration is the highest during at least the last 800,000 years.

Accumulation of atmospheric CO2 is the most accurately measured quantity in the global carbon budget. The uncertainty around the annual growth rate based on the multiple stations dtaset ranges between 0.11 and 0.72 GtC yr-1, with a mean of 0.61 GtC yr-1 for 1959–1980 and 0.18 GtC yr-1 for 1980–2011, when a larger set of stations were available.

The data is provided by the US National Oceanic and Atmospheric Administration Earth System Research Laboratory and includes data from the Scripps Institution of Oceanography.

graph Cumulative Carbon Emissions

The cumulative carbon emissions are the sum of the total CO2 emitted during a given period of time. Total cumulative emissions since the beginning of the Industrial Revolution, 1750 to 2012, were 385±20 GtC from fossil fuels and cement, and 205±70 from land use change. Using 1870 as the reference year (as in IPCC AR5 2013), cumulative emissions up to 2013 are 390±20 GtC from fossil fuels and cement, and 160±55 GtC from land use change, for a total of 550±60 GtC.

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