Will the increase in global average temperature stay below the EU policy target of not more than 2°C above pre-industrial levels?

Environment   Oct 20, 2017 by Kasandra Springford

Oct. 19 2017 Anna Wilson COP 23 MENTOR for  Slovenia

European Environmental Agency(2017). National emissions reported to the UNFCCC and to the EU Greenhouse Gas Monitoring Mechanism. (2017). European Environmental Agency .https://www.eea.europa.eu/data-and-maps/indicators...

Global and European temperature

Will the increase in global average temperature stay below the EU policy target of not more than 2°C above pre-industrial levels?

Key Points to Consider:

• According to three different observational records of global average annual near-surface (land and ocean) temperature, the last decade (2007–2016) was 0.87 to 0.92 °C warmer than the pre-industrial average, which makes it the warmest decade on record. Of the 17 warmest years on record, 16 have occurred since 2000. The year 2016 was the warmest on record, more than 1.1 °C warmer than the pre-industrial level, followed by 2015.
• The average annual temperature for the European land area for the last decade (2007–2016) was around 1.6 °C above the pre-industrial level, which makes it the warmest decade on record. Moreover, 2016 was the second warmest year (after 2014) in Europe since instrumental records began.
• Climate models project further increases in global average temperature over the 21st century (for the period 2081–2100 relative to 1986–2005) of between 0.3 and 1.7 °C for the lowest emissions scenario (RCP2.6) and between 2.6 and 4.8 °C for the highest emissions scenario (RCP8.5).
• All UNFCCC member countries have agreed on the long-term goal of keeping the increase in global average temperature to well below 2 °C compared with pre-industrial levels and have agreed to aim to limit the increase to 1.5 °C. For the three highest of the four RCPs, global average temperature increase is projected to exceed 2 °C compared with pre-industrial levels by 2050.
• Annual average land temperature over Europe is projected to increase by the end of this century (2071–2100 relative to 1971–2000) in the range of 1 to 4.5 °C under RCP4.5 and 2.5 to 5.5 °C under RCP8.5, which is more than the projected global average increase.
• The strongest warming is projected across north-eastern Europe and Scandinavia in winter and southern Europe in summer.
• The number of warm days (those exceeding the 90th percentile threshold of a baseline period) have doubled since 1960 across the European land area.Europe has experienced several extreme heat waves since 2000 (2003, 2006, 2007, 2010, 2014 and 2015). Under a high emissions scenario (RCP8.5), extreme heat waves as strong as these or even stronger are projected to occur as often as every two years in the second half of the 21st century. In southern Europe they are projected to be particularly strong.

Fig. 1: Global average near surface temperatures relative to the pre-industrial period

Past trends: global temperatureRecords of global average temperature show long-term warming trends since the end of the 19th century, which have been most rapid since the 1970s. Three independent analyses of global average temperature using near-surface observation records — HadCRUT4 [1], NOAA Global Temp [2], GISTEMP [3] by the NASA Goddard Institute for Space Studies and— show very similar amounts of warming. ERA-Interim reanalysis [4] dataset prepared by Copernicus Climate Change Service (C3S) (managed by European Centre for Medium-Range Weather Forecasts (ECMWF)) shows slightly higher increases in global temperature than datasets based only on in-situ observations. These differences arise from regions where there are few direct temperature measurements, especially over the Arctic and Antarctic where variability from year to year is high. They also arise from the adjustments needed to estimate sea surface temperature from measurements made at different depths and with different biases [5].All datasets show warming compared with pre-industrial temperatures (using the earliest observations from the period 1850–1900 as a proxy) of between 0.87 and 0.92 °C for the decade 2007–2016 (Figure 1). This magnitude of warming corresponds to almost half of the 2 °C warming that is compatible with the global climate stabilisation target of the EU and the ultimate objective of the UNFCCC [6]. Similar estimations of warming have also been obtained through ‘climate reanalysis’. The year 2016 was the warmest on record according to different near-surface temperature observational analyses, with temperatures greater than 1.1 °C above pre-industrial levels [7] . The year 2015 was the second warmest on record. Note that such statements are always associated with some uncertainty, primarily because of spatial and temporal gaps in the data record and different interpolation methods [8].Furthermore, the annual temperature anomalies are also strongly influenced by climate variability due to natural forcings (volcanic eruptions and solar activity) and by internal variability within the climate system (e.g. multi-annual climate fluctuations such as the ENSO, which influence the exchange of heat between the atmosphere and oceans) [9].Global ocean heat content has been increasing continuously since the 1950s down to at least 2 000 m, with no sign of any slow-down. Furthermore, a recent study that uses new datasets of the sea surface temperature and more sophisticated interpolation methods for data-sparse regions such as the Arctic suggests that the increase in global average temperature since 1998 was higher than the increase in the observed near-surface temperature as used for the IPCC AR5 [10]. Changing the start and end years also has an effect on the calculated rate of change, but this is less than that seen from newly available data and different methods for interpolation.Projections: global temperatureThe global average temperature will continue to increase throughout this century as a result of projected further increases in greenhouse gas concentrations. The CMIP5 climate projections summarised in the IPCC AR5 project that global temperature will increase by mid-century (2046–2065 relative to 1986–2005) by 0.4–1.6 °C for RCP2.6, 0.9–2.0 °C for RCP4.5, 0.8–1.8 °C for RCP6.0 and 1.4–2.6 °C for RCP8.5; the warming projections for the end of the century (2081–2100) are 0.3–1.7 °C for RCP2.6, 1.1–2.6 °C for RCP4.5, 1.4–3.1 °C for RCP6.0 and 2.6–4.8 °C for RCP8.5. All projections show greater warming over land than over the oceans. Projected warming is strongest in the Arctic at about twice the global average. These patterns are consistent with the observations during the latter part of the 20th century [12].The UNFCCC target of limiting global average warming to less than 2.0 °C above pre-industrial levels is projected to be exceeded between 2042 and 2050 by the three highest of the four RCP scenarios [13]. The lowest, RCP2.6, implies a strong reduction in greenhouse gas emissions over this century and negligible or even negative emissions at the end of the century [14].[1] Morice et al., “Quantifying Uncertainties in Global and Regional Temperature Change Using an Ensemble of Observational Estimates: The HadCRUT4 Data Set,”Journal of Geophysical Research 117, no. D8 (April 17, 2012): D08101, doi:10.1029/2011JD017187.[2] Karl et al., “Possible Artifacts of Data Biases in the Recent Global Surface Warming Hiatus,”Science 348, no. 6242 (June 26, 2015): 1469–72, doi:10.1126/science.aaa5632.[3] Hansen et al., “GISS Analysis of Surface Temperature Change,”Journal of Geophysical Research: Atmospheres 104, no. D24 (December 27, 1999): 30997–22, doi:10.1029/1999JD900835.[4] Dee et al., “The ERA-Interim Reanalysis: Configuration and Performance of the Data Assimilation System,”Quarterly Journal of the Royal Meteorological Society 137, no. 656 (April 1, 2011): 553–97, doi:10.1002/qj.828.[5] Simmons et al., “A Reassessment of Temperature Variations and Trends from Global Reanalyses and Monthly Surface Climatological Datasets,”Quarterly Journal of the Royal Meteorological Society 143, no. 702 (January 1, 2017): 101–19, doi:10.1002/qj.2949.[6] UNFCCC, “Report of the Conference of the Parties on Its Fifteenth Session, Held in Copenhagen from 7 to 19 December 2009” (Copenhagen: UNFCCC, 2009), http://unfccc.int/resource/docs/2009/cop15/eng/11a... (WMO) World Meteorological Organization, “WMO Statement on the Status of the Global Climate” (WMO, 2017), http://library.wmo.int/opac/index.php?lvl=notice_d... Blunden J. and Arndt, “State of the Climate in 2014,”Bulletin of the American Meteorological Society 96, no. 7 (July 1, 2015): ES1–32, doi:10.1175/2015BAMSStateoftheClimate.1.[9] IPCC,Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (Cambridge; New York: Cambridge University Press, 2013), http://www.climatechange2013.org/.[10] Karl et al., “Possible Artifacts of Data Biases in the Recent Global Surface Warming Hiatus”; John C. Fyfe et al., “Making Sense of the Early-2000s Warming Slowdown,”Nature Climate Change 6, no. 3 (March 2016): 224–28, doi:10.1038/nclimate2938.[12] M. Collins et al., “Long-Term Climate Change: Projections, Commitments and Irreversibility,” inClimate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, ed. T. F. Stocker et al. (Cambridge; New York: Cambridge University Press, 2013), 1029–1136, http://www.climatechange2013.org/images/report/WG1... Robert Vautard et al., “The European Climate under a 2 °C Global Warming,”Environmental Research Letters 9, no. 3 (March 1, 2014): 034006, doi:10.1088/1748-9326/9/3/034006.[14] Richard H. Moss et al., “The next Generation of Scenarios for Climate Change Research and Assessment,”Nature 463, no. 7282 (February 11, 2010): 747–56, doi:10.1038/nature08823.

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