Global greenhouse gas emissions

  • Image, Global greenhouse gas emissions.

    Greenhouse gas (GHG) emissions trap heat in the atmosphere and warm the planet. Human activities such as burning coal, oil, and gas emit additional greenhouse gases that mix in the atmosphere and become distributed over the globe. Over the past 150 years, emissions driven by economic and population growth have sharply increased the concentration of GHGs in the atmosphere to above pre-industrial levels, warming the planet and changing Earth’s climate.

    Of the greenhouse gases generated by human activity, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases have the greatest impact on climate change because they are good at absorbing energy and they accumulate in the atmosphere.

    We classified Global greenhouse gas emissions as a national indicator.

    Key findings

    Image, Increasing trend.    Increasing trend

    Gross emissions of global GHGs increased 51 percent from 1990 to 2013. This trend was assessed at the 95 percent confidence level. Global gross and net emissions of GHGs continue to increase, driven largely by the energy sector.

    For gross emissions in 2013:

    • Globally, most GHG emissions are from energy production (78 percent, of which 43 percent is for electricity/heat). This was followed by agriculture (11 percent).
    • Carbon dioxide (from fossil fuels and cement, and land-use change and forestry) made up 76 percent of all global emissions, followed by methane (16 percent) and nitrous oxide (6 percent).
    • China produced 26 percent of global GHG emissions, nearly twice as much as the next- highest producer, the United States. New Zealand contributed 0.17 percent. The top 12 emitting countries produced nearly double the amount of GHGs produced by all other countries.
    Figure 1
    Note: Net emissions include emissions and removals from land use change and forestry. Greenhouse gas emissions are in megatonnes of CO2 equivalent (Mt CO2-e).
    Figure 2

    Graph, Gross global greenhouse gas emissions by sector, 2013.

    Note: Greenhouse gas emissions are in megatonnes of CO2 equivalent (Mt CO2-e).

    Figure 3

    Graph, Gross global greenhouse gas emissions by gas type, 2013.

    Note: CO2 – carbon dioxide; CH4 – methane; N2O – nitrous oxide; F-gas – fluorinated gases. Greenhouse gas emissions are in megatonnes of CO2 equivalent (Mt CO2-e).
    Figure 4

    Graph, Gross global greenhouse gas emissions by country, 2013.

    Note: Greenhouse gas emissions are in megatonnes of CO2 equivalent (Mt CO2-e).
    Country percentages do not add up to 100 percent due to rounding.

    Definition and methodology

    Greenhouse gas (GHG) emissions are added to the atmosphere through human activities. They do not include natural sources such as biological processes or volcanic emissions. We report on gross and net GHG emissions. Gross emissions include emissions from energy, industrial processes, agriculture, and waste. Net emissions include emissions and removals from land-use change and forestry (LUCF). There may be large errors and uncertainties in CO2 removal data due to limitations on data collection.

    We obtained emissions data from the Climate Analysis Indicators Tool (CAIT) version 2.0 produced by the World Resources Institute (WRI). WRI compiles country-level emissions data from official sources, complemented by non-governmental sources “based on criteria such as completeness and relative accuracy and country datasets are produced by applying a consistent methodology” (World Resources Institute, 2015). Complete methodology can be found in CAIT country greenhouse gas emissions: Sources and methods (see ‘Related content’ box). CAIT data are used to examine New Zealand’s contribution to global GHG emission totals. However, the data may be inconsistent with New Zealand’s Greenhouse Gas Inventory, which is produced to meet New Zealand’s reporting obligations under the United Nations Framework Convention on Climate Change and the Kyoto Protocol.

    We report on four GHGs that are most important for warming because of their ability to absorb heat and their long residence time in the atmosphere:

    • carbon dioxide (CO2) – produced from fossil fuel (coal, oil, and gas) combustion, from burning of solid waste and wood, and from some chemical reactions, such as cement production
    • methane (CH4) – emitted by livestock and the decomposition of organic matter (such as in landfills) and during the production and transportation of coal and natural gas
    • nitrous oxide (N2O) – emitted mainly from agriculture but also from industrial processes and fossil fuel combustion
    • fluorinated gases (F-gases) – very strong human-made GHGs used in products such as refrigerators and air conditioners; emissions are from production and product use.

    CAIT reports on GHGs in megatonnes of CO2 equivalent (Mt CO2-e) using the 100-year global warming potentials (GWPs) from the second assessment report of the Intergovernmental Panel on Climate Change (IPCC, 1996). CO2 equivalents (CO2-e) allow the consistent reporting of GHG estimates by allowing non-CO2 gases to be expressed in CO2 equivalent terms based on each gas’s GWP.

    Data quality

    We classified Global greenhouse gas emissions as a national indicator.

    Relevance

       This case study is a direct measure of the ‘Human activities generating greenhouse gases’ topic.

    Accuracy

    Image, High accuracy.  The accuracy of the data source is of high quality.

    See Data quality information for more detail.

    References

    Intergovernmental Panel on Climate Change (IPCC) (1996). Climate change 1995: The science of climate change: contribution of working group I to the second assessment report of the Intergovernmental Panel on Climate Change (Houghton, JT, Ed). Cambridge and New York: Cambridge University Press.

    World Resources Institute (2015). CAIT country greenhouse gas emissions: Sources & methods (PDF 682kB). Retrieved from http://cait2.wri.org.

    Archived pages

    See Global greenhouse gas emissions (archived October 2017).

    Updated 19 October 2017

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