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WEATHER CLIMATE WATER The Global Climate in 20152019The Global Climate in 20152019 is part of the WMO Statements on Climate providing authoritative information on the state of the climate and impacts. It builds on operational monitoring systems at global, regional and national scales. It has been authored by: Peter Siegmund, lead author (Royal Netherlands Meteorological Institute), Jakob Abermann (University of Graz, Austria), Omar Baddour (WMO), Pep Canadell (CSIRO Climate Science Centre, Australia), Anny Cazenave (Laboratoire dEtudes en Gophysique et Ocanographie Spatiales, Centre National dEtudes Spatiales and Observatoire Midi-Pyrnes, France), Chris Derksen (Environment and Climate Change Canada), Arthur Garreau (Mto-France), Stephen Howell (Environment and Climate Change Canada), Matthias Huss (ETH Zrich), Kirsten Isensee (IOC-UNESCO), John Kennedy (UK Met Office), Ruth Mottram (Danish Meteorological Institute), Rodica Nitu (WMO), Selvaraju Ramasamy (Food and Agriculture Organization of the United Nations), Katherina Schoo (IOC-UNESCO), Michael Sparrow (WMO), Oksana Tarasova (WMO), Blair Trewin (Bureau of Meteorology, Australia), Markus Ziese (Deutscher Wetterdienst) The right of publication in print, electronic and any other form and in any language is reserved by WMO. Short extracts from WMO publications may be reproduced without authorization, provided that the complete source is clearly indicated. Editorial correspondence and requests to publish, reproduce or translate this publication in part or in whole should be addressed to: Chairperson, Publications Board World Meteorological Organization (WMO) 7 bis, avenue de la Paix Tel.: +41 (0) 22 730 84 03 P.O. Box 2300 Fax: +41 (0) 22 730 81 17 CH-1211 Geneva 2, Switzerland Email: publicationswmo.int NOTE The designations employed in WMO publications and the presentation of material in this publication do not imply the expression of any opinion what- soever on the part of WMO concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. 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Cover illustration: Adobe Stock, Frdrique Julliard World Meteorological Organization, 2019Contents Executive summary 3 Key findings 4 Greenhouse gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Ocean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Cryosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Precipitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 Extreme events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Attribution of extreme events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Highlights on prominent climate-related risks . . . . . . . . . . . . . . . . . . . . . . . . 18 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 DNASAISTEMP4D J COdHcd hc Cd :IOCUNESCO,NOAAPMEL,IAEAOAICC LBLPU Wm v- p .2h h h 211215 hwm ,v 1h h h p- l p HU lblm f 215217 L-l h x m b bl hm P (ufpp) (b$) 13 2 5.5 2.6 7.4 0.3 5 16.6 0.5 10 4.1 376 -W P 500 100 10 0.5 5 10 2017 2016 G 20152019 d r m m j r r r m d r fg w rmg. pim-h WGii i i(WG)iiip mD ppy()im hi i i () iDm2015x y m hpii i()Jy2016 2018,g h r hdr rd r r gmmrmmmdwrm xmm - xwrw wh 19812010 r gryy r fr m2015 2019. rxprdw d d w mmr -x 2017 d2018, rp y. 17 17 17 17 2017 2000Dr d rr Maria, r d D m $125b m r d rr Harvey $16b m r d hw d“r f r 8900Dr d h w w r dwd 20152019 201 201 201 201 201 2 201 2 201 20 01 201 01 01 201 2 2 201 201 201 20 2 20 20 20 201 01 201 201 20 201 20 20 2 20 8, 8, 8 8 8 8 8, 8, 8 8, 8 8 8, 8 8 8 8 8 8 8 8 8 8, 8, , , , , g h r hdr rd 3 Executive summary Compared to the previous five-year assess- ment period 20112015, the current five-year period 20152019 has seen a continued increase in carbon dioxide (CO 2 ) emissions and an accelerated increase in the atmos- pheric concentration of major greenhouse gases (GHGs), with growth rates nearly 20% higher. The increase in the oceanic CO 2con- centration has increased the oceans acidity. The five-year period 20152019 1is likely to be the warmest of any equivalent period on record globally, with a 1.1 C global tem - perature increase since the pre-industrial period and a 0.2 C increase compared to the previous five-year period. Continuing and accelerated trends have also predominated among other key climate indicators, including an acceleration of rising sea levels, a continued decline in the Arctic sea-ice extent, an abrupt decrease in Antarctic sea ice, continued ice mass loss in the glaciers and the Greenland and Antarctic ice sheets, and the clear downward trend in the northern hemisphere spring snow cover. More heat is being trapped in the ocean; 2018 had the largest ocean heat content values on record measured over the upper 700 meters. Precipitation has increased in some regions 1For 2019 only six months of data are currently available. and decreased in others. Heatwaves were the deadliest meteorological hazard in the 20152019 period, affecting all continents and resulting in new temperature records in many countries accompanied by unprece- dented wildfires that occurred in particular in Europe, North America and other regions. The 2019 northern summer saw record-breaking wildfires that expanded to the Arctic regions, setting new records, and wide-spread fires in the Amazon rainforest. Among all weather-related hazards, tropical cyclones were associated with the largest economic losses, with floods, landslides and associated loss and damage. The costliest hazard event was Hurricane Harvey in 2017, which led to an estimated economic loss of more than US$ 125 billion. Climate-related risks associated with climate variability and change exacerbated food insecurity in many places, in particular Africa due to the impact of drought, which increased the overall risk of climate-related illness or death. Higher sea-surface temperatures endangered marine life and ecosystems. Higher temperatures threaten to undermine development through adverse impacts on gross domestic product (GDP) in developing countries.4 GREENHOUSE GASES CO 2EMISSIONS AND GHG CONCENTRATIONS INCREASED CO 2is responsible for about 66% of the total radiative forcing from long-lived GHGs since pre-industrial time, with methane (CH 4 ) responsible for about 17% and nitrous oxide (N 2 O) for 6%. The global budget of anthropogenic carbon has continued to grow since 2015 due to the increase in CO 2 emissions from the combustion of fossil fuels (coal, oil and gas) and cement production. CO 2emissions from 2015 to 2019 are estimated to be at least 207 Gt CO 2 , exceeding the 200 Gt CO 2 2emitted during the previous five-year period of 20102014. Sinks for CO 2are distributed across the hemispheres, on land and oceans, but CO 2fluxes in the tropics (30S30N) are close to carbon neutral due to the CO 2sink being largely offset by emissions from deforestation. Sinks for CO 2 21 gigaton = 1 billion tons. in the southern hemisphere are dominated by the removal of CO 2by the oceans, while the stronger sinks in the northern hemisphere have similar contributions from both land and oceans. The latest analysis of observations from the WMO Global Atmosphere Watch shows that globally averaged surface concentrations calculated from this in-situ network for CO 2 , CH 4and N 2 O reached new highs (Figure 1). The growth rates of the CO 2 , CH 4and N 2 O concentrations in the atmosphere averaged over the 20152017 period for which data have been completed and processed are each about 20% higher than those over 20112015 (Table 1). 3Preliminary analysis shows that in 2018 the CO 2annual mean concentration at Mauna Loa Observatory, Hawaii, reached 408.52 ppm and the increase from 2017 to 2018 was 1.97 ppm. From January to August 2019 the increase in the concentration (deseasonalized trend) was 0.85 ppm. 3The current growth rate of CO 2of 2.6 ppm/year corresponds to a mass of about 50 kg CO 2per person per week worldwide. Key findingsCH 4concentration, ppb CH 4concentration 1900 1850 1800 1750 1700 1650 1600 1984 1987 1990 1993 1996 1999 2002 2005 2008 2011 2014 2017410 400 390 380 370 360 350 340 CO 2concentration 1984 1987 1990 1993 1996 1999 2002 2005 2008 2011 2014 2017N 2 O concentration, ppb 335 330 325 320 315 310 305 300 N 2 O concentration 1984 1987 1990 1993 1996 1999 2002 2005 2008 2011 2014 2017 CO 2concentration, ppm Table 1. Concentrations of CO 2(ppm), CH 4(parts per billion, ppb) and N 2 O (ppb), their growth rates (ppm/year for CO 2 , ppb/year for CH 4and N 2 O) averaged over 20152017 and 20112015, the relative change in growth rates between 20112015 and 20152017, and the percentage of 20152017 concentration to pre-industrial concentration (before 1750). Source: WMO Global Atmosphere Watch Concentration Growth rate 2015-2017 2011-2015 2015-2017 % to pre- industrial 2015-2017 2011-2015 % change CO 2 403 395.5 145 2.6 2.2 +18% CH 4 1851.7 1826.4 256 8.7 7.2 +21% N 2 O 329.1 326.2 122 0.87 0.73 +19% Figure 1. Time series of globally averaged concentrations of CO 2in ppm (left), CH 4in ppb (middle) and N 2 O in ppm (right). Blue lines are monthly mean global averaged concentrations, red lines are five-year running averaged monthly mean concentrations. Source: WMO Global Atmosphere WatchTEMPERATURE GLOBAL TEMPERATURE CONTINUES TO RISE, 20152019 IS SET TO BE WARMEST FIVE-YEAR PERIOD The years 2015 to 2018 were the four warmest years on record and 2019, although only six months of data are currently available, will likely join them as one of the five warmest years most likely second or third warmest if temperature anomalies continue at the current high levels to the end of the year. The average global temperature for 20152019, which is currently estimated to be 1.1 0.1 C above pre-industrial (18501900) level, is therefore likely to be the warmest of any equivalent period on record. It is 0.20 0.08 C warmer than the average for 20112015 (Figure 2). Continental average temperatures typically show greater variability than the global mean. Even so, five-year average temperatures for 20152019 are currently the warmest or second warmest on record for each of the inhabited continents (Figure 3). Figure 4 shows a map of temperature anomalies for 20152019 relative to the long-term average for 19812010. The global mean land-surface air temperature 4for 20152019 was approximately 1.7 C above pre-industrial and 0.3 C warmer than 2011 2015. Nearly all land areas were warmer than average, with only a few exceptions: an area of Canada and an area of the Antarctic in the Indian Ocean sector. The five-year average temperatures were the highest on record for large areas of the United States including Alaska, eastern parts of South America, most of Europe and the Middle East, northern Eurasia, Australia, and areas of Africa south of the Sahara. The global mean sea-surface temperature for 20152019 was approximately 0.8 C 4The global temperature assessment is based on five datasets: HadCRUT.4.6.0.0 (UK Met Office Hadley Centre and Climatic Research Unit, University of East Anglia), GISTEMP v4 (National Aeronautics and Space Administration Goddard Institute for Space Studies), NOAAGlobalTemp (National Oceanic and Atmospheric Administration (NOAA), National Centers for Environmental Information (NCEI), ERA5 (Euro- pean Centre for Medium-range Weather Forecasts), and JRA-55 (Japan Meteorological Agency). above pre-industrial and 0.13 C warmer than 20112015. Over the oceans, below-average sea-surface temperatures were observed to the south of Greenland (one of the few areas globally to have seen long-term cooling), the eastern Indian Ocean, an area off the coast of West Africa, some areas of the South Atlantic, the Drake Passage and an area of the Southern Ocean in the Pacific sector. Other areas were mostly warmer than average. Record warmth was recorded over areas of the north-east Pacific, the western North Atlantic, the western Indian Ocean, areas of the South Atlantic, and the Tasman Sea, which has seen a number of severe marine heatwaves in the past five years. 5 Figure 2. Five-year running average of global temperature anomalies (relative to pre-industrial) from 1854 to 2019 for five datasets: HadCRUT.4.6.0.0, NOAAGlobalTemp v5, GISTEMP v4, ERA5 and JRA-55. Data for 2019 to June. The anomalies are monthly anomalies averaged to years. Figure 3. Five-yea
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