EarthCharts

Reliable Information About Planet Earth

Climate Change

2.5°C

Predicted Global Warming

Without dramatic emissions reductions, global average temperatures could be 2.5°C higher than pre-industrial levels by 2050.

Data

KNMI Climate Change Atlas: GCM CMIP5 1

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RCP 2.6RCP 6.0
RCP 4.5RCP 8.5
Mean of values predicted by models
Minimum values predicted by models
Maximum values predicted by models

The graph above shows the predicted global temperature increases for four different scenarios of future greenhouse gas levels. The greater the temperature increase the greater the risks to ecosystems and human society. A temperature increase greater than 1.5°C is considered dangerous, and greater than 3.0°C is likely to be catastrophic. Under all the scenarios global temperature increases are likely to reach dangerous levels before 2040.

The data for the graph was derived from the outputs of CMIP5 (Coupled Model Intercomparison Project phase 5) climate models – an ensemble of coupled ocean-atmosphere general circulation models (GCMs), which were used in producing the IPCC Fifth Assessment Report.

Climate models are mathematical simulations of the Earth’s climate system. The models utilise scenarios for future greenhouse gas emissions to generate predictions of future climate change. The scenarios which form the inputs to the models are called Representative Concentration Pathways (RCPs). The RCPs consist of detailed sets of figures for potential future emissions of greenhouse gases, and their resulting atmospheric concentrations, which provide a common baseline for running climate models. Each RCP defines an emissions trajectory which results in a particular level of radiative forcing in 2100.

Emissions Scenarios

The key characteristics of the four RCP scenarios are given in the table below.

PathwayScenarioRadiative forcing Mean cumulative CO2 emissions 2012 to 21002100 atmospheric CO2 concentration 2100 atmospheric GHG concentration
RCP 2.6Rapid, substantial emissions reductions.Peaking at 3 Wm-2 declining to 2.6 Wm-2 by 2100.990 GtCO2421 ppm475 ppm CO2eq
RCP 4.5Emissions grow then decline significantly.Stabilising at 4.5 Wm-2 by 2100.2860 GtCO2 538 ppm630 ppm CO2eq
RCP 6.0Emissions grow then reduce somewhat.Growing to 6.0 Wm-2 by 2100, and continuing to rise.3885 GtCO2 670 ppm800 ppm CO2eq
RCP 8.5Emissions continue to grow.Growing to 8.5 Wm-2 by 2100, and continuing to rise.6180 GtCO2 936 ppm1313 ppm CO2eq

Data

The data for this graph was downloaded from the KNMI Climate Change Atlas. The settings used are shown in the following image:

References

  1. ‘KNMI Climate Explorer: Climate Change Atlas, GCM: CMIP5 (IPCC AR5 Atlas Subset)’ (KNMI – Royal Netherlands Meteorological Institute) http://climexp.knmi.nl/plot_atlas_form.py?id=someone@somewhere [accessed 8 January 2020] [↩]

Emissions Sources

Creative Commons License

Global Greenhouse Gas Emissions by Sector

Global greenhouse gas emissions can be attributed to different sectors of the economy. This provides a picture of the varying contributions of different types of economic activity to global warming, and helps in understanding the changes required to mitigate climate change.

Data

Emissions from combustion of fuels: IEA1 .

Other emissions: Climate Watch2.

Manmade greenhouse gas emissions can be divided into those that arise from the combustion of fuels to produce energy, and those generated by other processes. Around two thirds of greenhouse gas emissions arise from the combustion of fuels 2 .

Energy may be produced at the point of consumption, or by a generator for consumption by others. Thus emissions arising from energy production may categorised according to where they are emitted, or where the resulting energy is consumed. If emissions are attributed at the point of production, then electricity generators contribute about 25% of global greenhouse gas emissions 3 . If these emissions are attributed to the final consumer then 24% of total emissions arise from manufacturing and construction, 17% from transportation, 11% from domestic consumers, and 7% from commercial consumers. Around 4% of emissions arise from the energy consumed by the energy and fuel industry itself 1 .

The remaining third of emissions arise from processes other than energy production. 12% of total emissions arise from agriculture, 7% from land use change and forestry, 6% from industrial processes, and 3% from waste2 . Around 6% of emissions are fugitive emissions, which are waste gases released by the extraction of fossil fuels.

A version of this content was contributed to Wikipedia (https://en.wikipedia.org/wiki/Greenhouse_gas) on 6 March 2020.

  1. IEA, CO2 Emissions from Fuel Combustion 2018: Highlights (Paris: International Energy Agency, 2018) p.101 [↩] [↩]
  2. Climate Watch, ‘Climate Watch: Historical GHG Emissions, Sectors’ (Climate Watch, 2020) https://www.climatewatchdata.org/ghg-emissions?breakBy=sector&chartType=area§ors=846%2C849%2C845%2C848%2C847%2C853%2C850%2C855%2C854%2C852%2C851 (accessed 5 March 2020) [↩] [↩] [↩]
  3. IEA, CO2 Emissions from Fuel Combustion 2018: Highlights (Paris: International Energy Agency, 2018) p.98 [↩]

1.1°C

Observed Global Warming

In 2016 average global temperatures reached 1.1°C above the pre-industrial average.

Data

Met Office.1 

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Average global temperatures have been on an upward trend since the beginning of the 20th century. 2016 was a record high, with average global temperatures reaching 1.1°C above the 1850-1900 average. 2019 was the second warmest year on record at 1.05°C above the 1850-1900 average. Every year since 2001 has been warmer than any year of the 20th century, apart from 1998.

Over the past 40 years, each decade has been warmer than the previous one, with temperatures increasing by about 0.2°C per decade.

Data

As previous chart.

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References

  1. Met Office, ‘HadCRUT4 Dataset: Global Annual Average near-Surface Temperature Anomalies’ (Met Office, 2020) <https://www.metoffice.gov.uk/hadobs/hadcrut4/data/current/time_series/HadCRUT.4.6.0.0.annual_ns_avg.txt> (accessed 16 January 2020). [↩]

47Gt

Global Greenhouse Gas Emissions

In 2015 annual global greenhouse gas emissions reached 47GtCO2e.

Data

Greenhouse Gas Emissions – Potsdam Institute for Climate Impact Research1 

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In 2015 global anthropogenic greenhouse gas (GHG) emissions were about 47 GtCO2e, or 50GtCO2e including emissions from Land Use, Land Use Change, and Forestry (LULUCF). The majority of emissions (75% of total emissions) consist of CO2, and most of these are generated by burning of fuels (62% of total emissions).

References

  1. Gütschow, Johannes, Louise Jeffery, Robert Gieseke, and Ronja Gebel, ‘The PRIMAP-Hist National Historical Emissions Time Series (1850-2015). V.1.2.’ (Potsdam Institute for Climate Impact Research, 2018) https://doi.org/10.5880/pik.2019.001 [↩]

408ppm

In 2018 average atmospheric CO2 concentrations reached 408ppm.

Data:

Average annual atmospheric C02 concentrations: NOAA1

In 1750 atmospheric CO2 concentrations were about 278ppm2. Atmospheric CO2 concentrations have been increasing since the Industrial Revolution. The last time atmospheric CO2 concentrations were similar to today was 3 million years ago, when the global average temperature was 3°C higher, and sea levels were around 25m higher 3.

Atmospheric CO2 concentrations are currently increasing by about 2ppm per year4.

  1. NOAA, ‘ESRL Global Monitoring Division: Global Greenhouse Gas Reference Network – Trends in Atmospheric Carbon Dioxide’ (National Oceanic & Atmospheric Administration, 2019) https://www.esrl.noaa.gov/gmd/ccgg/trends/data.html [accessed 20 December 2019] [↩]
  2. Dlugokencky, E, ‘Atmospheric Composition: Long-Lived Greenhouse Gases’, State of the Climate in 2017 (Special Supplement): Bulletin of the American Meteorological Society, 99.8 (2018), S46-S49. Link [↩]
  3. Wuebbles, D. et al. ‘Our Globally Changing Climate’, in Climate Science Special Report: Fourth National Climate Assessment, Volume I, ed. by D Wuebbles et al. (Washington DC: US Global Change Research Program, 2017) p.53 https://doi.org/10.7930/J08S4N35 [↩]
  4. IPCC, Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (Geneva: Intergovernmental Panel on Climate Change, 2014) p.44. Link. [↩]