September 2020 was the warmest September since global record keeping began in 1880, NOAA’s National Centers for Environmental Information, NCEI, reported October 14.
The month was just 0.02 degrees Celsius warmer than the previous record, held jointly by September 2015 and 2016. NASA and the European Copernicus Climate Change Service also rated the month as the warmest September on record, and the Japan Meteorological Agency rated it as the third-warmest September on record. Minor differences in rankings often occur among various research groups, the result of different ways they handle data-sparse regions such as the Arctic.
The nine months of January through September were 1.02 degrees Celsius (1.84°F) above the 20th-century average, NCEI reported. That nine-month period ranks as the second-warmest such period on record, only 0.04 degrees Celsius (0.07°F) behind the record set in 2016. According to NCEI’s annual temperature outlook, the year 2020 is virtually certain to rank among the five warmest years on record, making each of the seven calendar years 2014 through 2020 one of the seven warmest years on record, dating back to 1880.
The NCEI outlook finds that 2020 has a 65% chance of displacing 2016 as the warmest year on record, and a 35% chance of being the second-warmest year on record. These odds are based on statistical relationships rather than unfolding weather and climate events, and the La Niña event now in progress (see below) will make 2020 less likely to be the warmest year on record.
Global ocean temperatures during September 2020 were the fourth-warmest on record, and global land temperatures the warmest on record. Global satellite-measured temperatures in September 2020 for the lowest eight kilometers of the atmosphere were the second-warmest or third-warmest in the 42-year record, according to the University of Alabama Huntsville and Remote Sensing Systems, respectively.
Global temperature records are more likely to be set during the peak of the solar cycle, and during strong El Niño events, when the extra heat from the tropical Pacific Ocean is given up to the atmosphere. Remarkably, the record warmth of September 2020 came during the minimum of one of the weakest 11-year solar cycles in the past century, and during a La Niña event, when cooling of the tropical Pacific Ocean helps cool global temperatures. That record warmth of September 2020, and for the year as a whole, underscores the dominant role of human-caused global warming in heating the planet.
In an October 14 press release, climate scientist James Hansen argued that global warming has accelerated over the past five years. As evidence, he pointed out that the global temperature increase, which had been stable at 0.18 degrees Celsius per decade, has increased substantially. He attributed the acceleration to changes in levels of sunlight-blocking aerosol particles in the atmosphere.
U.S. ties record for most billion-dollar weather disasters in a year: 16
In 2020 (as of October 7), 16 weather/climate disaster events with losses exceeding $1 billion each have occurred in the United States, according to NOAA/NCEI. This ties the all-time record for most billion-dollar weather disasters in an entire year, held jointly by 2011 and 2017. If the damages from last week’s Hurricane Delta eclipse $1 billion, 2020 will set a new record, with 17 billion-dollar weather disasters in the U.S. The 1980–2019 annual average is 6.6 events (CPI-adjusted); the annual average for the most recent 5 years (2015-2019) is 13.8 events (CPI-adjusted).
The 2020 list included one drought event, 11 severe storm events, three tropical cyclone events, and one wildfire event. Together, these events killed 188 people and cost over $46 billion.
Since 1980, the U.S. has sustained 279 separate billion-dollar weather and climate disasters (2020 dollars). The total cost of these 279 events exceeds $1.825 trillion. The U.S. disaster costs from billion-dollar weather events over the last five years (2016-2020) exceeded $550 billion, a record for any five-year period.
In a January 2020 review of the 2010-2019 U.S. billion dollar weather disasters, NOAA stated: “The number and cost of disasters are increasing over time due to a combination of increased exposure (i.e., values at risk of possible loss), vulnerability (i.e., how much damage does the intensity (wind speed, flood depth) at a location cause) and that climate change is increasing the frequency of some types of extremes that lead to billion-dollar disasters (NCA 2018, Chapter 2).”
U.N. calls attention to ‘staggering’ rise in natural disasters
An October 13 report by the United Nations Office for Disaster Risk Reduction (UNDRR) found a “staggering” rise in climate-related disasters, including extreme weather events: those nearly doubled, from 3,656 in 1980-1999 to 6,681 in 2000-2019. The number of major floods more than doubled, from 1,389 to 3,254, and the incidence of destructive storms increased from 1,457 to 2,034.
The U.N. report blamed human-caused climate change as a significant factor in the increased disasters, and warned, “It is baffling that we willingly and knowingly continue to sow the seeds of our own destruction, despite the science and evidence that we are turning our only home into an uninhabitable hell for millions of people.” The U.N. report authors called attention to “industrial nations that are failing miserably on reducing greenhouse gas emissions to levels commensurate with the desired goal of keeping global warming at 1.5 degrees Celsius as set out in the Paris Agreement.”
Eight global billion-dollar weather disasters in September; 35 for 2020 through September
Eight billion-dollar weather-related disasters hit the Earth last month, according to the September 2020 Catastrophe Report from insurance broker Aon, bringing this year’s total number of billion-dollar weather disasters through the end of September to 35. For comparison, both 2019 and 2018 had 40 billion-dollar weather disasters during the entire year. Details on each of the eight September 2020 events follow.
– Hurricane Sally, Alabama and Florida
Hurricane Sally made landfall near Gulf Shores, Alabama, on September 16 as a category 2 storm with 105 mph winds. Moving at less than 5 mph at landfall, Sally lingered over the Southeast for multiple days, dumping 10 to 20 inches of rain, with isolated amounts up to 30 inches, in southern Alabama and in the Florida panhandle. Sally killed eight people and caused at least $5 billion in damage.
– California wildfires
Four separate fires in California had generated over $1 billion in losses by the end of September: the CZU Complex ($3.5 billion), LNU Complex ($1.6 billion), North Complex ($1 billion), and Glass Fire ($1 billion). Eleven additional fires in California, Oregon, and Washington each had over $100 million in losses.
The unprecedented fire events of September included the largest fires on record in California (the August Complex, at over 1,000,000 acres burned) and also in Washington (the Washington Labor Day Fires, at over 400,000 acres burned). California’s August Complex Fire was the largest wildfire in the continental U.S. since the Great Fire of 1910 consumed over three million acres in Idaho and Montana.
The direct death toll from the Western U.S. fires in 2020 is at least 43, but the indirect death toll due to inhalation of wildfire smoke is likely in the thousands, researchers at Stanford University reported in a September 11 study. The research found that between 1,200 and 3,000 excess deaths occurred in California among people 65 and older between August 1 and September 10 from wildfire smoke-related causes.
“This is likely a substantial lower bound,” the researchers wrote, since “Oregon and Washington are being hit very hard right now too, and non-elderly are also surely affected. These overall effects can be in large part attributable to climate change, which has dramatically increased the likelihood and severity of wildfire.”
– Flooding in China
Seasonal monsoon flooding persisted in China in September, killing 11 people and causing $4 billion in damage. The total damage between June 1 and September 30 from China’s monsoon flooding is $32 billion, with 278 deaths. According to statistics from EM-DAT, the international disaster database, that total ranks as the third-most expensive non-U.S. weather disaster since accurate records began in 1990, behind 1998 flooding in China ($48 billion) and 2011 flooding in Thailand ($47 billion).
In a September 2020 study published in the Bulletin of the American Meteorological Society, “Each 0.5°C of Warming Increases Annual Flood Losses in China by More than US$60 Billion,” researchers found that annual average flood losses in China during the period 1984-2018 were $19.2 billion (2015 dollars), which was 0.5% of China’s GDP. Annual flood losses increased to $25.3 billion annually during the period 2006-2018. The study authors predicted that each additional 0.5 degrees Celsius of global warming will increase China flood losses by $60 billion per year.
– Flooding in India
Heavy monsoon rains severely affected nine states in India in September, killing 255 people and causing billions in damage. The total death toll from this year’s monsoon floods is 1,925, with economic losses of over $6 billion. This year’s total monsoon rainfall across India was 9% above average as of September 30, according to the India Meteorological Department. The 2019 monsoon season produced 110% of average rainfall; together, 2019 and 2020 are India’s wettest two-year period since the 1950s.
– Flooding in Pakistan
Heavy monsoon rains severely affected Pakistan in September, bringing the seasonal flooding death toll to 402, with $1.5 billion in damage.
Through the end of September, Earth had 35 billion-dollar weather disasters for the year, 21 of them in the United States, surpassing Aon’s previous U.S. record of 20 in 2017. Note that Aon’s list has more billion-dollar events for the U.S. (20) than NOAA’s list (16), mostly because Aon classified four different wildfires in California as separate billion-dollar events; NOAA treated all Western U.S. wildfires as one event.
Here is the 2020 list of billion-dollar weather disasters through September, listed by dollars of damage, according to Aon:
1. Flooding, China, Jun.-Sep., $32 billion, 279 killed;
2. Cyclone Amphan, India and Bangladesh, May 15-22, $13 billion, 118 killed;
3. Hurricane Laura, U.S., Aug. 27-29, $14 billion, 33 killed;
4. Severe weather (derecho), Midwest U.S., Aug. 8-12, $8 billion, four killed;
5. Flooding, India, Jun.-Aug., $6.0 billion, 1925 killed;
6. Hurricane Sally, Southeast U.S., Sep. 11-18, $5 billion, eight killed;
7. Hurricane Isaias, Eastern U.S., Aug. 2-4, $5 billion, 15 killed;
8. Flooding, Japan, Jul. 3-10, $5 billion, 82 killed;
9. Wildfire (CZU Complex Fire), California (U.S.), Aug. 17-Sep. 22, $3.5 billion, one killed;
10. Severe weather, Midwest, Plains, Southeast, and Mid-Atlantic U.S., Apr. 10-14, $3.45 billion, 38 killed;
11. Severe weather, Midwest, Plains, Southeast, and Mid-Atlantic U.S., Apr. 6-9, $3.0 billion, zero killed;
12. Severe weather, Central and Eastern U.S., Mar. 27-30, $2.9 billion, zero killed;
13. Windstorm Ciara, Western & Central Europe, Feb. 9-10, $2.6 billion, 14 killed;
14. Drought, northern and western China, Jan.-Aug., $2.4 billion, zero killed;
15. Severe weather/Nashville tornado, Central and Eastern U.S., Mar. 2-5, $2.4 billion, 25 killed;
16. Wildfires and Heatwave, Australia, Nov.-Jan., $2+ billion, 34 killed;
17. Severe weather, Plains, Southeast, and Midwest U.S., May 16-21, $1.9 billion, one killed;
18. Severe weather, Rockies, Plains, and Midwest U.S., May 20-24, $1.65 billion, two killed;
19. Wildfire (LNU Complex Fire), California (U.S.), Aug. 17-Oct. 2, $1.6 billion, five killed;
20. Severe weather, Australia, Jan. 18-20, $1.6 billion, zero killed;
21. Severe weather, Texas, May 27-28, $1.55 billion, zero killed;
22. Flooding, Pakistan, Jun.-Sep., $1.5 billion, 410 killed;
23. Typhoon Hagupit, China and Taiwan, Aug. 3-4, $1.5 billion, one killed;
24. Severe weather, Central and Eastern U.S., Feb. 3-8, $1.5 billion, five killed;
25. Severe weather, Plains, Southeast, and Midwest U.S., May 4-5, $1.5 billion, zero killed;
26. Severe weather, Plains, Southeast, and mid-Atlantic U.S., Apr. 21-24, $1.45 billion, seven killed;
27. Severe weather, Canada, Jun. 13-14, $1.4 billion, zero killed;
28. Severe weather, Central and Eastern U.S., Jan. 10-12, $1.28 billion, 12 killed;
29. Severe weather, Rockies, Midwest, Plains, Southeast U.S., Jul. 10-12, $1.2 billion, zero killed;
30. Flooding, Iran, Feb. 24–Apr. 30, $1.2 billion, 23 killed;
31. Severe weather, Midwest, Plains, Southeast, U.S., Apr. 27-30, $1.05 billion, zero killed;
32. Severe weather, Australia, Feb. 2-11, $1.0 billion, zero killed;
33. Wildfire (North Complex Fire), California (U.S.), Aug. 18-Oct. 1, $1.0 billion, 15 killed;
34. Wildfire (Glass Fire), California (U.S.), Sep. 27-Oct. 1, $1.0 billion, zero killed; and
35. Drought, U.S., Jan.-Sep., $1.0 billion, zero killed.
La Niña strengthens, predicted to surpass moderate-strength threshold
Over the past month, sea surface temperatures (SSTs) in the benchmark Niño 3.4 region of the eastern tropical Pacific (5°N-5°S, 170°W-120°W) were approximately 0.9 degrees Celsius below average, with 0.5 degrees below average being the threshold for “weak” La Niña conditions. The threshold for “moderate” La Niña conditions is Niño 3.4 SSTs of at least 1.0 degree Celsius below average.
Forecasters at NOAA and at Columbia University’s International Research Institute for Climate and Society expect La Niña conditions to continue through the winter (85% chance) and through the February-April period (60% chance). They predicted that La Niña would peak during the November-December-January period as a “moderate” event. If this forecast holds, the 2020-2021 La Niña will be the strongest since the “moderate” La Niña of 2011-2012. The most recent “strong” La Niña event (Niño 3.4 SSTs at least 1.5 degrees Celsius below average) occurred in 2010-2011.
Arctic sea ice: second-lowest September extent on record
Arctic sea ice extent during September 2020 was the second-lowest in the 42-year satellite record, behind 2012, according to the National Snow and Ice Data Center. Sea ice reached its annual minimum on September 15, 2020.
By the end of September, the Northern Sea route along the northern coast of Russia was still open to ice-free navigation, as it had been since mid-July. In the Canadian Arctic, the southern branch of the Northwest Passage (famed explorer Roald Amundsen’s route) had re-frozen enough to close the passage after it had been open much of August and September.
Antarctic sea ice extent in September 2020 was above average, and may have reached its annual maximum extent on September 28.
Notable global heat and cold marks for September 2020
– Hottest temperature in the Northern Hemisphere: 51.7°C (125.1°F) at Death Valley, California, September 5;
– Coldest temperature in the Northern Hemisphere: -48.1°C (-54.6°F) at Summit, Greenland, September 25;
– Hottest temperature in the Southern Hemisphere: 45.5°C (113.9°F) at Pozo Hondo, Paraguay, September 26;
– Coldest temperature in the Southern Hemisphere: -77.2°C (-107.0°F) at Dome Fuji, Antarctica, September 10;
– Highest 2020 average temperature to date (Jan. 1-September 30) worldwide: 32.1°C (89.8°F) at Yelimane, Mali; and
– Highest 2020 average temperature to date (Jan. 1-September 30) in the Southern Hemisphere: 29.8°C (85.6°F) at Surabaya Airport, Indonesia.
(Courtesy of Maximiliano Herrera (http://www.mherrera.org/temp.htm))
Major weather stations’ new all-time heat or cold records in September 2020
Among global stations with a period of record of at least 40 years, 46 set (not just tied) a new all-time heat record in September. Four of these stations broke their previous all-time record on multiple days. No stations set all-time cold records:
Nikaho (Japan) max. 38.2°C, September 3;
Amagasaki (Japan) max. 35.3°C, September 3;
Wajima (Japan) max. 38.6°C, September 3;
Osmanyie (Turkey) max. 45.3°C, September 3;
Mersin (Turkey) max. 41.5°C, September 3;
Iskenderun (Turkey) max. 43.7°C, September 3;
Jerusalem (Israel) max. 42.3°C, September 3; beaten again with 42.7°C on September 4;
Ayelet Hashahar (Israel) max. 46.6°C, September 3;
Kfar Blum (Israel) max. 47.0°C, September 3;
Eilat (Israel) max. 48.9°C, September 4;
Athienou (Cyprus) max. 46.0°C, September 4;
Nicosia (Cyprus) max. 46.2°C, September 4;
Kornos (Cyprus) max. 44.3°C, September 4;
Prodromos (Cyprus) max. 38.0°C, September 4;
El Cajon (California, USA) max. 45.6°C, September 5;
Alpine (California, USA) max. 45.0°C, September 5;
Woodland Hills (California, USA) max. 49.4°C, September 6;
Escondido (California, USA) max. 46.1°C, September 6;
Idlyllwild (California, USA) max. 40.0°C, September 6;
San Luis Obispo (California, USA) max. 47.2°C, September 6;
Pinnacles (California, USA) max. 47.8°C, September 6;
Tijuana (Mexico) max. 43.3°C, September 6;
Cuiaba (Brazil) max. 42.6°C, September 10; beaten again with 42.7°C on September 13 and again with 43.7°C on September 30;
Conceicao do Araguaia (Brazil) max. 41.7°C, September 10;
Canefield Airport (Dominica) max. 35.7°C, September 15: (New national record high for Dominica);
Corrientes (Argentina) max. 42.5°C, September 26; beaten again with 43.3°C on September 30;
Pozo Hondo (Paraguay) max. 45.5°C, September 26: (New national record high for Paraguay);
Asuncion Airport (Paraguay) max. 42.3°C, September 26;
San Estanislao (Paraguay) max. 40.8°C, September 26;
Coxim (Brazil) max. 44.1°C, September 30;
Paranaiba (Brazil) max. 42.8°C, September 30;
Rondonopolis (Brazil) max. 42.7°C, September 30;
Diamantino (Brazil) max. 42.5°C, September 30;
Votuporanga (Brazil) max. 41.8°C, September 30;
Lins (Brazil) max. 41.9°C, September 30;
Catanduva (Brazil) max. 41.2°C, September 30;
Campo Grande (Brazil) max. 40.8°C, September 30;
Presidente Prudente (Brazil) max. 40.8°C, September 30;
Rancharia (Brazil) max. 40.3°C, September 30;
Londrina (Brazil) max. 39.4°C, September 30;
Jales (Brazil) max. 41.7°C, September 30;
Ciudad del Este Guarani Airport (Paraguay) max. 42.4°C, September 30;
Asuncion Airport (Paraguay) max. 42.4°C, September 30;
Salto del Guaira (Paraguay) max. 42.0°C, September 30;
Robore (Bolivia) max. 42.0°C, September 30; and
San Matias (Bolivia) max. 43.3°C, September 30.
11 all-time national/territorial heat records set or tied in 2020
As of October 19, 2020, eleven nations or territories had set or tied an all-time national heat record:
Colombia: 42.6°C (108.7°F) at Jerusalen, February 19 (tie);
Ghana: 44.0°C (111.2°F) at Navrongo, April 6;
Cuba: 39.2°C (102.6°F) at Palo Seco, April 10; broken again April 11 with 39.3°C (102.7°F) at Veguitas, and again on April 12 with 39.7°C (103.5°F) at Veguitas;
Mayotte, France department: 36.4°C (97.5°F) at Trevani, April 14;
Taiwan: 40.5°C (104.9°F) at Taimali Research Center, July 16;
Lebanon: 45.4°C (113.7°F) at Houche Al Oumara, July 27;
United States: 54.4°C (129.9°F) at Death Valley, California, August 16;
Japan: 41.1°C (106.0°F) at Hamamatsu, August 17;
Dominica: 35.7°C (96.3°F) at Canefield Airport, September 15;
Puerto Rico (U.S. territory): 37.8°C (100.0°F ) at Aguirre, September 17; and
Paraguay: 45.5°C (113.9°F ) at Pozo Hondo, September 26.
No all-time national/territorial cold records have been set thus far in 2020.
(Courtesy of Maximiliano Herrera)
102 additional monthly national/territorial 2020 heat records beaten or tied as of October 19
In addition to the 11 all-time national heat records, 102 other national monthly heat records have been set so far in 2020, for a total of 113 national monthly heat records:
– January (13): Norway, South Korea, Angola, Congo Brazzaville, Dominica, Mexico, Indonesia, Guinea Bissau, Gambia, Sao Tome and Principe, Cuba, British Indian Ocean Territory, Singapore;
– February (12): Spain, Antarctica, Azerbaijan, Costa Rica, The Bahamas, Switzerland, Maldives, Gambia, Russia, Seychelles, Dominican Republic, U.S. Virgin Islands;
– March (7): Paraguay, Cabo Verde, Mozambique, Seychelles, United States, Thailand, Northern Mariana Islands;
– April (14): Paraguay, Niger, St. Barthelemy, Honduras, Guernsey, Haiti, Congo Brazzaville, Kyrgyzstan, Mongolia, China, Saba, Northern Mariana Islands, U.S. Virgin Islands, Dominican Republic;
– May (10): Niger, Greece, Saba, Cyprus, Solomon Islands, Turkey, Haiti, Kazakhstan, Chile, Uzbekistan;
– June (6): Maldives, Thailand, U.S. Virgin Islands, Saba, Kenya, Ghana;
– July (7): Mozambique, U.S. Virgin Islands, Laos, Myanmar, Iran, Saudi Arabia, Northern Mariana Islands;
– August (6): Solomon Islands, Mexico, Australia, Cocos Islands, Paraguay, U.S. Virgin Islands;
– September (18): Laos, Taiwan, Japan, Turkey, Lebanon, Israel, Jordan, Cyprus, Mexico, Belgium, Netherlands, Luxembourg, Botswana, St. Barthelemy, Mayotte, Argentina, Brazil, British Indian Ocean Territory; and
– October (9): Algeria, Brazil, Tunisia, Turkey, Cyprus, Jordan, Peru, Myanmar, Northern Mariana Islands.
Two monthly national/territorial cold records beaten or tied in 2020
– April: St. Eustatius; and
– October: Aruba.
(Courtesy of Maximiliano Herrera)
Hemispherical and continental temperature records in 2020
– Highest minimum temperature ever recorded in the Northern Hemisphere in January: 29.1°C (84.4°F) at Bonriki, Kiribati, January 17;
– Highest maximum temperature ever recorded in North America in January: 42.0°C (107.6°F) at Vicente Guerrero, Mexico, January 21;
– Highest temperature ever recorded in continental Antarctica and highest February temperature ever recorded in Antarctica plus the surrounding islands: 18.4°C (65.1°F) at Base Esperanza, February 6;
– Highest minimum temperature ever recorded in February in Antarctica: 7.6°C (45.7°F) at Base Marambio, February 9;
– Highest minimum temperature ever recorded in March in the Northern Hemisphere: 32.0°C (89.6°F) at Yelimane, Mali, February 23;
– Highest minimum temperature ever recorded in May in the Southern Hemisphere: 31.1°C (88.0°F) at Argyle, Australia, April 2;
– Highest minimum temperature ever recorded in May in Europe: 30.1°C (86.2°F) at Emponas, Greece, May 17;
– Highest minimum temperature ever recorded in May in North America: 35.0°C (95.0°F) at Death Valley, California (U.S.), May 28;
– Highest temperature ever recorded in the polar regions: 38.0°C (100.4°F) at Verkhoyansk, Russia, June 20;
– Highest reliable temperature ever recorded on Earth: 54.4°C (129.9°F) at Death Valley, California, August 16;
– Highest reliable minimum temperature ever recorded in August in North America: 40.0°C (104.0°F) at Death Valley, California (U.S.), August 17; and
– Highest temperature ever recorded in Australia and Oceana in August: 40.7°C (105.3°F) at Yampi Sound, Australia, August 22; beaten again with 41.2°C (106.2°F) at West Roebuck, Australia, on August 23.
Bob Henson contributed to this post. Editor’s note: this post was updated October 19 to add the new October monthly record for the Northern Mariana Islands.