Instrumental temperature record

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Some global average temperature records date to 1850. Datasets from different sources are highly correlated.

The instrumental temperature record is a record of temperatures within Earth's climate based on direct, instrument-based measurements of air temperature and ocean temperature. Instrumental temperature records are distinguished from indirect reconstructions using climate proxy data such as from tree rings and ocean sediments.[1] Instrument-based data are collected from thousands of meteorological stations, buoys and ships around the globe. Whilst many heavily-populated areas have a high density of measurements, observations are more widely spread in sparsely populated areas such as polar regions and deserts, as well as over many parts of Africa and South America.[2] Measurements were historically made using mercury or alcohol thermometers which were read manually, but are increasingly made using electronic sensors which transmit data automatically. The longest-running temperature record is the Central England temperature data series, which starts in 1659. The longest-running quasi-global records start in 1850.[3]

Temperatures are also measured in the upper atmosphere using a variety of methods, including radiosondes launched using weather balloons, a variety of satellites, and aircraft.[4] Satellites are used extensively to monitor temperatures in the upper atmosphere but to date have generally not been used to assess temperature change at the surface. In recent decades, global surface temperature datasets have been supplemented by extensive sampling of ocean temperatures at various depths, allowing estimates of ocean heat content.

The record shows a rising trend in global average surface temperatures (i.e. global warming) driven by human-induced emissions of greenhouse gases. The global average and combined land and ocean surface temperature show a warming of 1.09 °C (range: 0.95 to 1.20 °C) from 1850–1900 to 2011–2020, based on multiple independently produced datasets.[5]: 5  The trend is faster since 1970s than in any other 50-year period over at least the last 2000 years.[5]: 8  Within this long-term upward trend, there is short-term variability because of natural internal variability (e.g. ENSO, volcanic eruption), but record highs have been occurring regularly.

Methods[edit]

Instrumental temperature records are based on direct, instrument-based measurements of air temperature and ocean temperature, unlike indirect reconstructions using climate proxy data such as from tree rings and ocean sediments.[1] The longest-running temperature record is the Central England temperature data series, which starts in 1659. The longest-running quasi-global records start in 1850.[3] Temperatures on other time scales are explained in global temperature record.

"Global temperature" can have different definitions. There is a small difference between air and surface temperatures.[6]: 12 

Global record from 1850[edit]

Exterior of a Stevenson screen
Interior of a Stevenson screen

The period for which reasonably reliable instrumental records of near-surface temperature exist with quasi-global coverage is generally considered to begin around 1850. Earlier records exist, but with sparser coverage, largely confined to the Northern Hemisphere, and less standardized instrumentation.

The temperature data for the record come from measurements from land stations and ships. On land, temperatures are measured either using electronic sensors, or mercury or alcohol thermometers which are read manually, with the instruments being sheltered from direct sunlight using a shelter such as a Stevenson screen. The sea record consists of ships taking sea temperature measurements, mostly from hull-mounted sensors, engine inlets or buckets, and more recently includes measurements from moored and drifting buoys. The land and marine records can be compared.

Land and sea measurement and instrument calibration is the responsibility of national meteorological services. Standardization of methods is organized through the World Meteorological Organization (and formerly through its predecessor, the International Meteorological Organization).[7]

Most meteorological observations are taken for use in weather forecasts. Centers such as European Centre for Medium-Range Weather Forecasts show instantaneous map of their coverage; or the Hadley Centre show the coverage for the average of the year 2000. Coverage for earlier in the 20th and 19th centuries would be significantly less. While temperature changes vary both in size and direction from one location to another, the numbers from different locations are combined to produce an estimate of a global average change.

Absolute temperatures v. anomalies[edit]

Records of global average surface temperature are usually presented as anomalies rather than as absolute temperatures. A temperature anomaly is measured against a reference value or long-term average.[8] For example, if the reference value is 15 °C, and the measured temperature is 17 °C, then the temperature anomaly is +2 °C (i.e., 17 °C −15 °C).

Temperature anomalies are useful for deriving average surface temperatures because they tend to be highly correlated over large distances (of the order of 1000 km).[9] In other words, anomalies are representative of temperature changes over large areas and distances. By comparison, absolute temperatures vary markedly over even short distances. A dataset based on anomalies will also be less sensitive to changes in the observing network (such as a new station opening in a particularly hot or cold location) than one based on absolute values will be.

The Earth's average surface absolute temperature for the 1961–1990 period has been derived by spatial interpolation of average observed near-surface air temperatures from over the land, oceans and sea ice regions, with a best estimate of 14 °C (57.2 °F).[10] The estimate is uncertain, but probably lies within 0.5 °C of the true value.[10] Given the difference in uncertainties between this absolute value and any annual anomaly, it's not valid to add them together to imply a precise absolute value for a specific year.[11]

Total warming and trends[edit]

NASA animation portrays global surface temperature changes since 1880. Blues denote cooler temperatures and reds denote warmer temperatures.
Projected temperature and sea-level rise relative to the 2000–2019 mean for RCP climate change scenarios up to 2500.[12][13]

The global average and combined land and ocean surface temperature, show a warming of 1.09 °C (range: 0.95 to 1.20 °C) from 1850–1900 to 2011–2020, based on multiple independently produced datasets.[5]: 5 The trend is faster since 1970s than in any other 50-year period over at least the last 2000 years.[5]: 8 

Most of the observed warming occurred in two periods: around 1900 to around 1940 and around 1970 onwards;[14] the cooling/plateau from 1940 to 1970 has been mostly attributed to sulphate aerosol.[15][16] Some of the temperature variations over this time period may also be due to ocean circulation patterns.[17]

Land air temperatures are rising faster than sea surface temperatures. Land temperatures have warmed by 1.59 °C (range: 1.34 to 1.83 °C) from 1850–1900 to 2011–2020, while sea surface temperatures have warmed by 0.88 °C (range: 0.68 to 1.01 °C) over the same period.[5]: 5 

For 1980 to 2020, the linear warming trend for combined land and sea temperatures has been 0.18 °C to 0.20 °C per decade, depending on the data set used.[18]: Table 2.4 

The IPCC Fifth Assessment Report found that it was unlikely that any uncorrected effects from urbanisation, or changes in land use or land cover, have raised global land temperature changes by more than 10%.[19]: 189  The Sixth Assessment Report confirmed this whilst noting that larger urbanisation signals have been found locally in some rapidly urbanising regions, such as eastern China.[18]: Section 2.3.1.1.3 

Global surface temperature reconstruction over the last 2000 years using proxy data from tree rings, corals, and ice cores in blue.[20] Directly observed data is in red.[21]
Multiple independent instrumental datasets show that the climate system is warming.[22] The 2011–2020 decade warmed to an average 1.09 °C [0.95–1.20 °C] compared to the pre-industrial baseline (1850–1900).[23] Surface temperatures are rising by about 0.2 °C per decade,[24] with 2020 reaching a temperature of 1.2 °C above the pre-industrial era.[25] Since 1950, the number of cold days and nights has decreased, and the number of warm days and nights has increased.[26]

Warmest periods[edit]

Warmest years[edit]

In recent decades, new high temperature records have substantially outpaced new low temperature records on a growing portion of Earth's surface.[27]

The warmest years in the instrumental temperature record have occurred in the last decade (i.e. 2012-2021). The World Meteorological Organization reported in March 2021 that 2016 and 2020 were the two warmest years in the period since 1850.[28]

Each individual year from 2015 onwards has been warmer than any year prior to 1850.[28] In other words: each of the seven years in 2015-2021 was clearly warmer than any pre-2014 year.

There is a long-term warming trend, and there is variability about this trend because of natural sources of variability (e.g. ENSO such as 2014–2016 El Niño event, volcanic eruption).[29] Not every year will set a record but record highs are occurring regularly.

While record-breaking years can attract considerable public interest,[30] individual years are less significant than the overall trend.[31][32] Some climatologists have criticized the attention that the popular press gives to "warmest year" statistics.[33][31]

Based on the NOAA dataset (note that other datasets produce different rankings[34]), the following table lists the global combined land and ocean annually averaged temperature rank and anomaly for each of the 10 warmest years on record.[35] For comparison: IPCC uses the mean of four different datasets and expresses the data relative to 1850–1900.[citation needed] Although global instrumental temperature records begin only in 1850, reconstructions of earlier temperatures based on climate proxies, suggest these recent years may be the warmest for several centuries to millennia, or longer.[18]: 2–6 

Top 10 warmest years (data from NOAA) (1880–2021)
Rank Year Anomaly °C Anomaly °F
1 2016 1.00 1.80
2 2020 0.98 1.76
3 2019 0.95 1.71
4 2015 0.93 1.67
5 2017 0.91 1.64
6 2021 0.84 1.51
7 2018 0.83 1.49
8 2014 0.74 1.33
9 2010 0.72 1.30
10 2013 0.68 1.22

Warmest decades[edit]

Global warming by decade: In the last four decades, global average surface temperatures during a given decade have been higher than the average temperature in the preceding decade (data for 1850 to 2020 based on HadCRUT datasets).

Numerous drivers have been found to influence annual global mean temperatures. An examination of the average global temperature changes by decades reveals continuing climate change: each of the last four decades has been successively warmer at the Earth's surface than any preceding decade since 1850. The IPCC Sixth Assessment report found that it was more likely than not that the most recent decade (2011-2020) was warmer than any multi-centennial period in the past 11,700 years.[18]: 2–6 

The following chart is from NASA data of combined land-surface air and sea-surface water temperature anomalies.[36]

Combined land-surface air and sea-surface water temperature anomalies (data from NASA)
Years Temperature anomaly, °C (°F) from 1951 to 1980 mean Change from previous decade, °C (°F)
1880–1889 −0.274 °C (−0.493 °F) N/A
1890–1899 −0.254 °C (−0.457 °F) +0.020 °C (0.036 °F)
1900–1909 −0.259 °C (−0.466 °F) −0.005 °C (−0.009 °F)
1910–1919 −0.276 °C (−0.497 °F) −0.017 °C (−0.031 °F)
1920–1929 −0.175 °C (−0.315 °F) +0.101 °C (0.182 °F)
1930–1939 −0.043 °C (−0.077 °F) +0.132 °C (0.238 °F)
1940–1949 0.035 °C (0.063 °F) +0.078 °C (0.140 °F)
1950–1959 −0.02 °C (−0.036 °F) −0.055 °C (−0.099 °F)
1960–1969 −0.014 °C (−0.025 °F) +0.006 °C (0.011 °F)
1970–1979 −0.001 °C (−0.002 °F) +0.013 °C (0.023 °F)
1980–1989 0.176 °C (0.317 °F) +0.177 °C (0.319 °F)
1990–1999 0.313 °C (0.563 °F) +0.137 °C (0.247 °F)
2000–2009 0.513 °C (0.923 °F) +0.200 °C (0.360 °F)
2010–2019 0.753 °C (1.355 °F) +0.240 °C (0.432 °F)
2020–2029 (incomplete) 0.91 °C (1.64 °F) +0.157 °C (0.28 °F)

Factors influencing global temperature[edit]

Colored bars show how El Niño years (red, regional warming) and La Niña years (blue, regional cooling) relate to overall global warming (based on data from HadCRUT).

Factors that influence global temperature include:

  • Greenhouse gases trap outgoing radiation warming the atmosphere which in turn warms the land (greenhouse effect).
  • El Niño–Southern Oscillation (ENSO): El Niño generally tends to increase global temperatures. La Niña, on the other hand, usually causes years which are cooler than the short-term average.[37] El Niño is the warm phase of the El Niño–Southern Oscillation (ENSO) and La Niña the cold phase. In the absence of other short-term influences such as volcanic eruptions, strong El Niño years are typically 0.1 °C to 0.2 °C warmer than the years immediately preceding and following them, and strong La Niña years 0.1 °C to 0.2 °C cooler. The signal is most prominent in the year in which the El Niño/La Niña ends.[citation needed]
  • Aerosols and volcanic eruptions: Aerosols diffuse incoming radiation generally cooling the planet. On a long-term basis, aerosols are primarily of anthropogenic origin, but major volcanic eruptions can produce quantities of aerosols which exceed those from anthropogenic sources over periods of time up to a few years. Volcanic eruptions which are sufficiently large to inject significant quantities of sulphur dioxide into the stratosphere can have a significant global cooling effect for one to three years after the eruption. This effect is most prominent for tropical volcanoes as the resultant aerosols can spread over both hemispheres. The largest eruptions of the last 100 years, such as the Mount Pinatubo eruption in 1991 and Mount Agung eruption in 1963-1964, have been followed by years with global mean temperatures 0.1 °C to 0.2 °C below long-term trends at the time.[citation needed]
  • Land use change like deforestation can increase greenhouse gases through burning biomass. Albedo can also be changed.
  • Incoming solar radiation varies very slightly, with the main variation controlled by the approximately 11-year solar magnetic activity cycle.

Robustness of evidence[edit]

There is a scientific consensus that climate is changing and that greenhouse gases emitted by human activities are the primary driver.[38] The scientific consensus is reflected, for example, by the Intergovernmental Panel on Climate Change (IPCC), an international body which summarizes existing science, and the U.S. Global Change Research Program.[38]

The methods used to derive the principal estimates of global surface temperature trends—HadCRUT3, NOAA and NASA/GISS—are largely independent.

Other reports and assessments[edit]

Refer to caption
This graph shows how short-term variations occur in the global temperature record. However, the graph still shows a long-term trend of global warming. Image source: NCADAC.[39]

The U.S. National Academy of Sciences, both in its 2002 report to President George W. Bush, and in later publications, has strongly endorsed evidence of an average global temperature increase in the 20th century.[40]

The preliminary results of an assessment carried out by the Berkeley Earth Surface Temperature group and made public in October 2011, found that over the past 50 years the land surface warmed by 0.911 °C, and their results mirrors those obtained from earlier studies carried out by the NOAA, the Hadley Centre and NASA's GISS. The study addressed concerns raised by "skeptics"[41][42] including urban heat island effect, "poor"[41] station quality, and the "issue of data selection bias"[41] and found that these effects did not bias the results obtained from these earlier studies.[41][43][44][45]

The Berkeley Earth dataset has subsequently been made operational and is now one of the datasets used by IPCC and WMO in their assessments.

Global surface and ocean datasets[edit]

National Oceanic and Atmospheric Administration (NOAA) maintains the Global Historical Climatology Network (GHCN-Monthly) data base containing historical temperature, precipitation, and pressure data for thousands of land stations worldwide.[46] Also, NOAA's National Climatic Data Center (NCDC)[47] of surface temperature measurements maintains a global temperature record since 1880.[48]

HadCRUT, a collaboration between the University of East Anglia's Climatic Research Unit and the Hadley Centre for Climate Prediction and Research

NASA's Goddard Institute for Space Studies maintains GISTEMP.

More recently the Berkeley Earth Surface Temperature dataset. These datasets are updated frequently, and are generally in close agreement.

Map of the land-based long-term monitoring stations included in the Global Historical Climatology Network. Colors indicate the length of the temperature record available at each site.

Internal climate variability and global warming[edit]

One of the issues that has been raised in the media is the view that global warming "stopped in 1998".[49][50] This view ignores the presence of internal climate variability.[50][51] Internal climate variability is a result of complex interactions between components of the climate system, such as the coupling between the atmosphere and ocean.[52] An example of internal climate variability is the El Niño–Southern Oscillation (ENSO).[50][51] The El Niño in 1998 was particularly strong, possibly one of the strongest of the 20th century, and 1998 was at the time the world's warmest year on record by a substantial margin.

Cooling over the 2007 to 2012 period, for instance, was likely driven by internal modes of climate variability such as La Niña.[53] The area of cooler-than-average sea surface temperatures that defines La Niña conditions can push global temperatures downward, if the phenomenon is strong enough.[53] The slowdown in global warming rates over the 1998 to 2012 period is also less pronounced in current generations of observational datasets than in those available at the time in 2012. The temporary slowing of warming rates ended after 2012, with every year from 2015 onwards warmer than any year prior to 2015, but it is expected that warming rates will continue to fluctuate on decadal timescales through the 21st century.[54]: Box 3.1 

Satellite temperature records[edit]

The most recent climate model simulations give a range of results for changes in global-average temperature. Some models show more warming in the troposphere than at the surface, while a slightly smaller number of simulations show the opposite behaviour. There is no fundamental inconsistency among these model results and observations at the global scale.[55]

The satellite records used to show much smaller warming trends for the troposphere which were considered to disagree with model prediction; however, following revisions to the satellite records, the trends are now similar.

Siting of temperature measurement stations[edit]

The U.S. National Weather Service Cooperative Observer Program has established minimum standards regarding the instrumentation, siting, and reporting of surface temperature stations.[56] The observing systems available are able to detect year-to-year temperature variations such as those caused by El Niño or volcanic eruptions.[57]

Another study concluded in 2006, that existing empirical techniques for validating the local and regional consistency of temperature data are adequate to identify and remove biases from station records, and that such corrections allow information about long-term trends to be preserved.[58] A study in 2013 also found that urban bias can be accounted for, and when all available station data is divided into rural and urban, that both temperature sets are broadly consistent.[59]

Related research[edit]

Trends and predictions[edit]

Each of the seven years in 2015-2021 was clearly warmer than any pre-2014 year, and this trend is expected to be true for some time to come (that is, the 2016 record will be broken before 2026 etc.).[citation needed] A decadal forecast by the World Meteorological Organisation issued in 2021 stated a probability of 40% of having a year above 1.5 C in the 2021-2025 period.[citation needed]

The IPCC Sixth Assessment Report projects that global warming is very likely to reach 1.0 °C to 1.8 °C by the late 21st century under the very low GHG emissions scenario. In an intermediate scenario global warming would reach 2.1 °C to 3.5 °C, and 3.3 °C to 5.7 °C under the very high GHG emissions scenario.[5]: SPM-17  These projections are based on climate models in combination with observations.[60]: TS-30 

Regional temperature changes[edit]

Average surface air temperatures from 2011 to 2021 compared to the 1956–1976 average. Source: NASA
Top graphic (comprehensive): 196 rows represent 196 countries, grouped by continent. Each row has 118 color-coded annual temperatures, showing 19012018 warming patterns in each region and country.[61][62]
- Bottom graphic (summary): global average 19012018.[63]
- Data visualization: warming stripes.

The changes in climate are not expected to be uniform across the Earth. In particular, land areas change more quickly than oceans, and northern high latitudes change more quickly than the tropics. There are three major ways in which global warming will make changes to regional climate: melting ice, changing the hydrological cycle (of evaporation and precipitation) and changing currents in the oceans.

See also[edit]

References[edit]

  1. ^ a b "What Are "Proxy" Data?". NCDC.NOAA.gov. National Climatic Data Center, later called the National Centers for Environmental Information, part of the National Oceanographic and Atmospheric Administration. 2014. Archived from the original on 10 October 2014.
  2. ^ "GCOS - Deutscher Wetterdienst - CLIMAT Availability". gcos.dwd.de. Retrieved 12 May 2022.
  3. ^ a b Brohan, P., J.J. Kennedy, I. Harris, S.F.B. Tett, P.D. Jones (2006). "Uncertainty estimates in regional and global observed temperature changes: a new dataset from 1850". J. Geophys. Res. 111 (D12): D12106. Bibcode:2006JGRD..11112106B. CiteSeerX 10.1.1.184.4382. doi:10.1029/2005JD006548. S2CID 250615.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. ^ "Remote Sensing Systems". www.remss.com. Retrieved 19 May 2022.
  5. ^ a b c d e f IPCC (2021). "Summary for Policymakers" (PDF). The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. ISBN 978-92-9169-158-6.
  6. ^ IPCC (2018). "Summary for Policymakers" (PDF). Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty. pp. 3–24.
  7. ^ Guide to the Global Observing System (PDF). WMO. 2007. ISBN 978-9263134882.
  8. ^ CMB and Crouch, J. (17 September 2012). "Global Surface Temperature Anomalies: Background Information – FAQ 1". NOAA NCDC. {{cite journal}}: Cite journal requires |journal= (help)
  9. ^ Hansen, J.E. (20 November 2012). "Data.GISS: GISS Surface Temperature Analysis (GISTEMP)". New York, NY, USA: NASA GISS. {{cite journal}}: Cite journal requires |journal= (help). Website curator: Schmunk, R.B.
  10. ^ a b Jones PD, New M, Parker DE, Martin S, Rigor IG (1999). "Surface air temperature and its changes over the past 150 years". Reviews of Geophysics. 37 (2): 173–199. Bibcode:1999RvGeo..37..173J. doi:10.1029/1999RG900002.
  11. ^ "Data.GISS: GISTEMP — the Elusive Absolute Surface Air Temperature".
  12. ^ "By 2500 earth could be alien to humans". Scienmag: Latest Science and Health News. 14 October 2021. Archived from the original on 18 October 2021. Retrieved 18 October 2021.
  13. ^ Lyon, Christopher; Saupe, Erin E.; Smith, Christopher J.; Hill, Daniel J.; Beckerman, Andrew P.; Stringer, Lindsay C.; Marchant, Robert; McKay, James; Burke, Ariane; O’Higgins, Paul; Dunhill, Alexander M.; Allen, Bethany J.; Riel-Salvatore, Julien; Aze, Tracy (2021). "Climate change research and action must look beyond 2100". Global Change Biology. 28 (2): 349–361. doi:10.1111/gcb.15871. ISSN 1365-2486. PMID 34558764. S2CID 237616583.
  14. ^ IPCC AR5 Chapter 2 page 193
  15. ^ Houghton(eds); et al. (2001). "Climate Change 2001: Working Group I: The Scientific Basis – Chapter 12: Detection of Climate Change and Attribution of Causes". IPCC. Archived from the original on 11 July 2007. Retrieved 13 July 2007. {{cite web}}: |author= has generic name (help)
  16. ^ "Ch 6. Changes in the Climate System". Advancing the Science of Climate Change. 2010. doi:10.17226/12782. ISBN 978-0-309-14588-6., in US NRC 2010, p. 207
  17. ^ Swanson, K.L.; Sugihara, G.; Tsonis, A.A. (22 September 2009). "Long-term natural variability and 20th century climate change". Proc. Natl. Acad. Sci. U.S.A. 106 (38): 16120–3. Bibcode:2009PNAS..10616120S. doi:10.1073/pnas.0908699106. PMC 2752544. PMID 19805268.
  18. ^ a b c d Gulev, S. K., P. W. Thorne, J. Ahn, F. J. Dentener, C. M. Domingues, S. Gerland, D. Gong, D. S. Kaufman, H. C. Nnamchi, J. Quaas, J. A. Rivera, S. Sathyendranath, S. L. Smith, B. Trewin, K. von Shuckmann, R. S. Vose, 2021, Changing State of the Climate System (Chapter 2). In: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S. L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M. I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J. B. R. Matthews, T. K. Maycock, T. Waterfield, O. Yelekçi, R. Yu and B. Zhou (eds.)]. Cambridge University Press. In Press.
  19. ^ IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.
  20. ^ Neukom et al. 2019b.
  21. ^ "Global Annual Mean Surface Air Temperature Change". NASA. Retrieved 23 February 2020.
  22. ^ EPA 2016: The U.S. Global Change Research Program, the National Academy of Sciences, and the Intergovernmental Panel on Climate Change (IPCC) have each independently concluded that warming of the climate system in recent decades is "unequivocal". This conclusion is not drawn from any one source of data but is based on multiple lines of evidence, including three worldwide temperature datasets showing nearly identical warming trends as well as numerous other independent indicators of global warming (e.g. rising sea levels, shrinking Arctic sea ice).
  23. ^ IPCC AR6 WG1 Summary for Policymakers 2021, p. SPM-5
  24. ^ IPCC SR15 Ch1 2018, p. 81.
  25. ^ WMO 2021, p. 6.
  26. ^ IPCC AR5 WG1 Ch2 2013, p. 162.
  27. ^ "Mean Monthly Temperature Records Across the Globe / July 2021 Global Land and Ocean". NCDC.NOAA.gov. National Climatic Data Center (NCDC) of the National Oceanographic and Atmospheric Administration (NOAA). August 2021. Archived from the original on 2 September 2021.
  28. ^ a b "The State of the Global Climate 2020". public.wmo.int. 11 July 2017. Retrieved 17 March 2022.
  29. ^ "2016: one of the warmest two years on record" (Press release). Met Office of the United Kingodom. 18 January 2017. Retrieved 20 January 2017.
  30. ^ "Climate change: Data shows 2016 likely to be warmest year yet". BBC News Online. 18 January 2017. Retrieved 19 January 2017.
  31. ^ a b Potter, Sean; Cabbage, Michael; McCarthy, Leslie (19 January 2017). "NASA, NOAA Data Show 2016 Warmest Year on Record Globally" (Press release). NASA. Retrieved 20 January 2017.
  32. ^ Brumfiel, Geoff (18 January 2017). "U.S. Report Confirms 2016 Was The Hottest Year On Record". NPR. Retrieved 20 January 2017.
  33. ^ Schmidt, Gavin (22 January 2015). "Thoughts on 2014 and ongoing temperature trends". RealClimate. Retrieved 4 September 2015.
  34. ^ "2017 was second hottest year on record, after sizzling 2016 - report". Reuters. 4 January 2018.
  35. ^ "Global Climate Report – Annual 2020". NOAA. Retrieved 14 January 2021.
  36. ^ "Data.GISS: GISS Surface Temperature Analysis (GISTEMP v4)". data.giss.nasa.gov. Retrieved 17 March 2022.
  37. ^ "NOAA National Climatic Data Center, State of the Climate: Global Analysis for Annual 2014". NOAA. Retrieved 21 January 2015.
  38. ^ a b Joint-statement by leaders of 18 scientific organizations: American Association for the Advancement of Science, American Chemical Society, American Geophysical Union, American Institute of Biological Sciences, American Meteorological Society, American Society of Agronomy, American Society of Plant Biologists, American Statistical Association, Association of Ecosystem Research Centers, Botanical Society of America, Crop Science Society of America, Ecological Society of America, Natural Science Collections, Alliance Organization of Biological Field Stations, Society for Industrial and Applied Mathematics, Society of Systematic Biologists, Soil Science Society of America, University Corporation for Atmospheric Research (21 October 2009). "Joint-statement on climate change by leaders of 18 scientific organizations" (PDF). Washington DC, USA: American Association for the Advancement of Science. Archived from the original (PDF) on 6 August 2013. {{cite journal}}: Cite journal requires |journal= (help); |author= has generic name (help)CS1 maint: multiple names: authors list (link)
  39. ^ Walsh, J.; et al., Figure 6: Short-term Variations Versus Long-term Trend, in: D. Is the global temperature still increasing? Isn't there recent evidence that it is actually 1 cooling?, in: Appendix I: NCA Climate Science – Addressing Commonly Asked Questions from A to Z (PDF), in NCADAC 2013, p. 1065
  40. ^ "Understanding and Responding to Climate Change – Highlights of National Academies Reports" (PDF). United States National Academies. 2005. Archived from the original (PDF) on 11 June 2007. Retrieved 13 July 2007.
  41. ^ a b c d "Cooling the Warming Debate: Major New Analysis Confirms That Global Warming Is Real". Science Daily. 21 October 2011. Retrieved 22 October 2011.
  42. ^ see also: PBS (10 January 2007). "Interviews – James Hansen: Hot Politics: FRONTLINE: PBS". PBS. {{cite journal}}: Cite journal requires |journal= (help). "(...) The 1990s is the real appearance of the science skeptics. How much did they come after you? I actually don't like the word "skeptics" for them; I think it's better to call them "contrarians," because skepticism is part of science; all scientists are skeptics (...)"
  43. ^ Ian Sample (20 October 2011). "Global warming study finds no grounds for climate sceptics' concerns". The Guardian. Retrieved 22 October 2011.
  44. ^ Richard Black (21 October 2011). "Global warming 'confirmed' by independent study". BBC News. Retrieved 21 October 2011.
  45. ^ "Climate change: The heat is on". The Economist. 22 October 2011. Retrieved 22 October 2011.
  46. ^ "GHCN-Monthly Version 2". NOAA. Retrieved 13 July 2007.
  47. ^ NCDC State of the Climate Global Analysis, April 2010
  48. ^ "Global Surface Temperature Anomalies". National Climatic Data Center. Retrieved 16 June 2010.
  49. ^ e.g., see Carter, B. (9 April 2006). "There IS a problem with global warming... it stopped in 1998". The Daily Telegraph.
  50. ^ a b c Edited quote from public-domain source: Scott, M. (31 December 2009). "Short-term Cooling on a Warming Planet, p.1". ClimateWatch Magazine. NOAA. Introduction. Archived from the original on 19 February 2013. Retrieved 22 September 2012.
  51. ^ a b Met Office, Fitzroy Road (14 September 2009). "Global warming set to continue". UK Met Office. Archived from the original on 27 October 2012. {{cite journal}}: Cite journal requires |journal= (help)
  52. ^ Albritton, D.L.; et al. (2001). Houghton, J.T.; et al. (eds.). Box 1: What drives changes in climate? in: Technical Summary, in: Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press.
  53. ^ a b Edited quote from public-domain source: Scott, M. (31 December 2009). "Short-term Cooling on a Warming Planet, p.3". ClimateWatch Magazine. NOAA. Deciphering Natural Variability.
  54. ^ Eyring, V., N. P. Gillett, K. M. Achuta Rao, R. Barimalala, M. Barreiro Parrillo, N. Bellouin, C. Cassou, P. J. Durack, Y. Kosaka, S. McGregor, S. Min, O. Morgenstern, Y. Sun, 2021, Human Influence on the Climate System (chapter 3). In: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S. L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M. I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J. B. R. Matthews, T. K. Maycock, T. Waterfield, O. Yelekçi, R. Yu and B. Zhou (eds.)]. Cambridge University Press. In Press.
  55. ^ Temperature Trends in the Lower Atmosphere – Understanding and Reconciling Differences
  56. ^ NOAA National Weather Service Cooperative Observer Program: Proper Siting
  57. ^ Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences. Archived 3 February 2007 at the Wayback Machine Thomas R. Karl, Susan J. Hassol, Christopher D. Miller, and William L. Murray, editors, 2006. A Report by the Climate Change Science Program and the Subcommittee on Global Change Research, Washington, DC.
  58. ^ Peterson, Thomas C. (August 2006). "Examination of potential biases in air temperature caused by poor station locations". Bull. Amer. Meteor. Soc. 87 (8): 1073–89. Bibcode:2006BAMS...87.1073P. doi:10.1175/BAMS-87-8-1073. S2CID 122809790.
  59. ^ Zeke Hausfather, Matthew J. Menne, Claude N. Williams, Troy Masters, Ronald Broberg, David Jones (30 January 2013). "Quantifying the effect of urbanization on U.S. Historical Climatology Network temperature records". Journal of Geophysical Research. 118 (2): 481–494. Bibcode:2013JGRD..118..481H. doi:10.1029/2012JD018509.{{cite journal}}: CS1 maint: uses authors parameter (link)
  60. ^ Arias, P.A., N. Bellouin, E. Coppola, R.G. Jones, G. Krinner, J. Marotzke, V. Naik, M.D. Palmer, G.-K. Plattner, J. Rogelj, M. Rojas, J. Sillmann, T. Storelvmo, P.W. Thorne, B. Trewin, K. Achuta Rao, B. Adhikary, R.P. Allan, K. Armour, G. Bala, R. Barimalala, S. Berger, J.G. Canadell, C. Cassou, A. Cherchi, W. Collins, W.D. Collins, S.L. Connors, S. Corti, F. Cruz, F.J. Dentener, C. Dereczynski, A. Di Luca, A. Diongue Niang, F.J. Doblas-Reyes, A. Dosio, H. Douville, F. Engelbrecht, et al., 2021: Technical Summary. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press. In Press.
  61. ^ Hawkins, Ed (21 July 2019). "#ShowYourStripes / Temperature changes around the world (1901-2018)". Climate Lab Book. Archived from the original on 2 August 2019. (Direct link to image).
  62. ^ Amos, Jonathan (21 June 2019). "The chart that defines our warming world / Is this the simplest way to show what is meant by global warming? The chart below organises all the countries of the world by region, time and temperature. The trend is unmistakeable". BBC. Archived from the original on 29 June 2019. (Link to png image)
  63. ^ Hawkins, Ed (4 December 2018). "2018 visualisation update / Warming stripes for 1850-2018 using the WMO annual global temperature dataset". Climate Lab Book. Archived from the original on 17 April 2019. LICENSE / Creative Commons License / These blog pages & images are licensed under a Creative Commons Attribution-ShareAlike 4.0 International License. (Direct link to image).

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