This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
September 2019 was the planet's warmest September since record keeping began in 1880, said NOAA's National Centers for Environmental Information (NCEI) on October 16. NASA rated September 2019 as the second warmest September on record, just 0.1 degrees Centigrade behind September 2016. Minor differences between the NOAA and NASA rankings can result because of differing techniques on how they handle data-sparse regions like the Arctic.
Global ocean temperatures during September 2019 were tied for second warmest on record, according to NOAA, and global land temperatures were the warmest on record. Global satellite-measured temperatures in September 2019 for the lowest 8 km of the atmosphere were the warmest in the 42-year record, beating the previous record from 2017, according to the University of Alabama Huntsville (UAH) and RSS.
2019 a lock to be among the 5 warmest years in Earth’s recorded history
The January through September year-to-date period was the second warmest on record globally, behind 2016, according to NOAA. Their global annual temperature ranking outlook indicated that it is virtually certain that 2019 will end among the top five warmest years in Earth’s history. This means that the six warmest years on record globally since 1880 will be the last six years—2014 through 2019—with the peak occurring during the strong El Niño year of 2016. NOAA gave a 95% chance that 2019 would be a top-four warmest year on record, but only a 0.11% chance that it would be the warmest year on record.
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This near-record global warmth in 2019 is all the more remarkable since it is occurring during the minimum of the weakest solar cycle in 100+ years, and during a year when a strong El Niño has not been present (though a weak El Niño was present in the first half of 2019, ending in July). Record-warm global temperatures typically occur during strong El Niño events, and when the solar cycle is near its maximum. The near-record warmth of 2019 is thus a testament to how greatly human-caused global warming is impacting the planet.
Figure 1. Departure of temperature from average for September 2019, the warmest September for the globe since record keeping began in 1880, according to NOAA. Record warm temperatures were observed across parts of the North and Western Pacific Ocean, the Barents Sea, the south-central contiguous U.S., the Atlantic and Indian oceans, the Middle East, Mongolia and northern China, and Africa. North America and the Gulf of Mexico both had their warmest Septembers on record. In the U.S., it was the second warmest September on record, behind only 1998. No land or ocean areas had record cold temperatures. Credit: NOAA
Four billion-dollar weather disasters in September 2019
Four billion-dollar weather-related disasters hit the Earth last month, according to the September 2019 Catastrophe Report from insurance broker Aon: Hurricane Dorian (Bahamas, U.S., and Canada), Tropical Storm Imelda (U.S.), Typhoon Faxai (Japan), and flooding in Spain. The 2019 tally of billion-dollar weather disasters was 23 as of the end of September. Ten of these disasters were in the U.S., making it the fifth year in a row for ten or more billion-dollar weather disasters—an unprecedented occurrence:
1. Flooding, India, 6/1 – 10/5, $10+ billion, 1850 killed
2. Flooding, Central U.S., 5/1 – 7/31, $10+ billion, 0 killed
3. Typhoon Lekima, China, 6/1 – 7/1, $10+ billion, 73 killed
4. Flooding, China, 6/1 – 7/1, $8.5+ billion, 225 killed
5. Flooding, Iran, 3/17 - 4/9, $8.3 billion, 77 killed
6. Typhoon Faxai, Japan, 9/8 – 9/9, $7 billion, 3 killed
7. Flooding, Central U.S., 3/12 – 4/30, $5 billion, 3 killed
8. Hurricane Dorian, 8/31 – 9/7, Bahamas, U.S., and Canada, $4+ billion, 664 dead or missing
9. Severe Weather, Rockies, Plains, Midwest, Southeast U.S., 5/26 – 5/31, $2.75 billion, 3 killed
10. Flooding, Spain, 9/11 – 9/15, $2.4 billion, 7 killed
11. Flooding, Argentina, Uruguay, 1/1 - 1/20, $2.3 billion, 5 killed
12. Cyclone Fani, India, Bangladesh, 5/3 – 5/5, $2+ billion, 89 killed
13. Tropical Storm Imelda, Texas/Louisiana (U.S.), 9/17 – 9/20, $2+ billion, 1 killed
14. Cyclone Idai, Mozambiqe, Zimbabwe, Malawi, 3/3 - 3/18, $2 billion, 1007+ killed
15. Flooding, Australia, 1/28 - 2/7, $1.9 billion, 3 killed
16. Drought, India, 1/1 – now, $1.75 billion, 0 killed
17. Severe Weather, Plains, Midwest U.S., 3/23 – 3/25, $1.5 billion, 0 killed
18. Windstorm Eberhard, Central & Western Europe, 3/10, $1.5 billion, 2 killed
19. Severe Weather, Central/Eastern U.S., 2/22 - 2/26, $1.4 billion, 4 killed
20. Severe Weather, Plains, Midwest, Southeast U.S., 5/4 – 5/10, $1.2 billion, 1 killed
21. Severe Weather, Plains, Midwest, Southeast, Northeast U.S., 4/12 – 4/15, $1.1 billion, 9 killed
22. Severe Weather, Central Europe, 6/10 – 6/12, $1.1 billion, 0 killed
23. Severe Weather, Plains, Midwest, Southeast U.S., 3/12 – 3/17, $1 billion, 5 killed
Neutral El Niño conditions reign
NOAA’s October 10 monthly discussion of the state of the El Niño/Southern Oscillation (ENSO) stated that neutral ENSO conditions existed, with neither an El Niño nor a La Niña event in progress. Over the past month, sea surface temperatures (SSTs) in the benchmark Niño3.4 region of the eastern tropical Pacific have been below the 0.5°C above-average threshold need to be considered El Niño conditions, they said.
Forecasters at NOAA and the International Research Institute for Climate and Society (IRI) are calling for a roughly 60% chance of neutral conditions continuing through the spring of 2020. They put the odds of an El Niño forming by spring at about 25 - 30%, and the odds of a La Niña event at 10 - 15%. Neutral periods lasting more than a year are fairly infrequent; the only three such periods we’ve seen this century were in 2001-02, 2003-04, and 2012-14.
Figure 2. Departure of sea surface temperatures (SSTs) in the benchmark Niño 3.4 region (in the equatorial Pacific) ending on October 14, 2019. Over the past month, SSTs were below the 0.5°C above-average threshold need to be considered El Niño conditions. Credit: Levi Cowan tropicaltidbits.com
September Arctic sea ice extent: third lowest on record
The long-term decline in Arctic sea ice due to human-caused global warming was in strong evidence during September 2019. Arctic sea ice extent during September was the third lowest in the 41-year satellite record, behind 2012 and 2007, according to the National Snow and Ice Data Center (NSIDC). The annual minimum in sea ice extent occurred on September 18 and was tied with 2007 and 2016 for the second lowest yearly minimum on record, behind 2012. While the northern branch of the Northwest Passage through Canadian arctic waters was choked with ice and closed to navigation this year, the southern branch did open during September, according to NSIDC. The waters of the Northern Sea Route along the coast of Siberia were open for ice-free navigation for over a month, beginning in late August.
Notable global heat and cold marks for September 2019
Hottest temperature in the Northern Hemisphere: 49.5°C (121.1°F) at Omidieh, Iran, 1 September
Coldest temperature in the Northern Hemisphere: -45.4°C (-49.7°F) at Geo Summit, Greenland, 19 September
Hottest temperature in the Southern Hemisphere: 43.8°C (106.9°F) at Nueve Lunas, Paraguay, 16 September
Coldest temperature in the Southern Hemisphere: -78.7°C (-109.8°F) at Concordia, Antarctica, 1 September
(Courtesy of Maximiliano Herrera)
Major weather stations that set (not tied) all-time heat or cold records in September 2019
Among global stations with a period of record of at least 40 years, 8 set new all-time heat records in September. There were no stations that set all-time cold records.
Diamantino (Brazil) max. 42.0°C, 6 September
Vieux Habitants (Guadeloupe,France) max. 36.6°C, 9 September: New territorial record high for Guadeloupe
Saba Airport (Saba, Netherlands) max. 33.5°C, 13 September
Maracaju (Brazil) max. 41.4°C, 15 September
Dourados (Brazil) max. 41.2°C, 16 September
Poxoreo (Brazil) max. 43.5°C, 17 September
Pastaza (Ecuador) max. 34.2°C, 26 September
Montego Bay (Jamaica) max. 37.0°C, 30 September
Nineteen all-time national/territorial heat records set or tied in 2019
As of October 15, all-time high temperature records have been tied or broken in nineteen of the world’s nations and territories, making 2019 the second most prolific year on record for all-time national heat records. The largest number of all-time national/territorial heat records set or tied in a single year was the 22 heat records that occurred in 2016, according to international records researcher Maximiliano Herrera; 2017 holds third place with 14 heat records. Here are 2019’s national heat records, as of October 15, with notations by Herrera at the end:
Christmas Island (Australia): 31.6°C (88.9°F), 19 January
Reunion Islands (France): 37.0°C (98.6°F), 25 January
Angola: 41.6°C (106.9°F), 22 March
Togo: 43.5°C (110.3°F), 28 March (later tied on 4 April)
Vietnam: 43.4°C, (110.1°F), 20 April
Jamaica: 39.1°C (102.4°F) at Shortwood Teacher’s College, 22 June
France: 46.0°C (114.8°F) at Verargues, 28 June
Andorra: 39.4°C (102.9°F) at Borda Vidal, 28 June
Cuba: 39.1°C (102.4°F) at Veguitas (Cuba), 30 June
Jersey (crown dependency of Britain): 36.0°C (96.8°F) at Jersey Airport, 23 July (record tied)
Belgium: 41.8°C (107.2°F) at Begijnendijk, 25 July
Germany: 41.2°C (108.7°F) at Tonisvorst and Duisburg, 25 July*
Luxembourg: 40.8°C (105.4°F) at Steinsel, 25 July
Netherlands: 40.7°C (105.3°F) at Gilze Rijen, 25 July
United Kingdom: 38.7°C (101.7°F) at Cambridge, 25 July
Norway: 35.6°C (96.1°F) at Laksfors, 27 July (record tied)**
Syria: 50.0°C (122.0°F) at Hasakah, 13 August***
Wake Island (United States Minor Outlying Islands): 36.6°C (97.9°F) at Wake Airfield, 15 August
Guadeloupe (French territory): 36.6°C (97.9°F) at Vieux Habitants, 9 September
* The official national record of 42.6°C measured the same day at Lingen is irregular and totally incompatible with nearby stations data and with the atmospheric conditions. The station has a history of overexposure and of being unreliable and is set to be moved. Despite this, the record was made official by the German DWD. Estimated overexposure is estimated to be about 2°C.
** This tied record was dismissed by the Norwegian Met. Service on weak grounds despite being reliable and compatible with nearby stations data and the atmospheric conditions. Confoundingly, the totally unreliable and irregular records set in August 1901—30 years before the installment of the first reliable temperature shelter with a Stevenson Screen in Oslo—have not been dismissed.
*** The Hasakah, Syria station has 1°C precision. The max temperature of 50.0°C is supported by nearby stations, so the record can be accepted.
No all-time national cold records have been set thus far in 2019. Most nations do not maintain official databases of extreme temperature records, so the national temperature records reported here are in many cases not official. If you reproduce this list of extremes, please cite Maximiliano Herrera as the primary source of the weather records. Jérôme Reynaud also tracks all-time and monthly national extreme temperature records at geoclimat.org (in French language).
Ninety-nine additional monthly national/territorial heat records beaten or tied in 2019 as of October 15
In addition to the 19 all-time any-month heat records listed above, 99 national monthly records have also been beaten or tied in 2019. If we add together these totals, there have been 118 monthly national/territorial heat records beaten or tied in 2019; zero monthly cold records have been set.
January: Micronesia, Paraguay, Angola, Equatorial Guinea, Palau
February: Chile, Marshall Islands, Guyana, United Kingdom, Denmark, Sweden, Netherlands, Belgium, Luxembourg, Andorra, Austria, Hungary, Jersey, Guernsey, Slovakia, San Marino, Slovenia, Angola, Papua New Guinea
March: Australia, Marshall Islands, India, Kenya, Northern Marianas
April: Angola, Togo, French Southern Territories, Mayotte, Taiwan, Kenya, Mauritius
May: Kenya, Indonesia, Niger, French Southern Territories, Syria, Tonga, Laos, Vietnam, Japan, Israel, Cyprus, Turkey
June: India, Tonga, Namibia, Lithuania, Senegal, Qatar, Chile, Laos, Vietnam, Germany, Czech Republic, Poland, Switzerland, Luxembourg, Liechtenstein, St. Barthelemy
July: Iran, Wallis and Futuna, Namibia, Jordan, Israel, Hong Kong, Chile, Bonaire, Mauritius
August: Taiwan, Cape Verde, Namibia, Wallis and Futuna, Kenya
September: Oman, Brunei, Niger,
Saba,Nicaragua, Paraguay, Brazil, Solomon Islands, Morocco, Comoros, Laos, Jamaica, Kenya
October: Hong Kong, Mongolia, Morocco, Micronesia, Qatar, Kuwait, North Korea, China
(Courtesy of Maximiliano Herrera)
Hemispheric and continental temperature records in 2019
- Highest minimum temperature ever recorded in the Southern Hemisphere: 35.9°C (96.6°F) at Noona, Australia, 18 January. The record was beaten again on 26 January, with a minimum temperature of 36.6°C (97.9°F) recorded at Borrona Downs, Australia. This is also the highest minimum temperature on record for the globe for the month of January.
- Highest temperature ever recorded in the world in March: 48.1°C (118.6°F) on 10 March at Roebourne, Australia.
- Highest temperature ever recorded in Asia in March: 46.9°C (116.4°F) at Kapde, India, 25 March. The data comes from a state (not central government) station, and may not be officially recognized, but is supported by data from several nearby stations.
- Highest minimum temperature ever recorded in June in the Southern Hemisphere: 28.9°C (84.0°F) at Funafuti, Tuvalu on 15 June.
- Highest minimum temperature ever recorded in August in the Southern Hemisphere (tie): 28.2°C (82.8°F) at Funafuti, Tuvalu on 15 August.
- Highest temperature ever recorded in October in the Northern Hemisphere: 47.6°C (117.7°F) at Al Wafra, Kuwait on 3 October.
- Highest minimum temperature ever recorded in October: 33.0°C (91.4°F) at Sedom, Israel on 15 October.