Confirmed: 2016 the Warmest Year in History of Global Recordkeeping

For the third year in a row, Earth has experienced the warmest surface temperatures in global data extending back to 1880. In its annual climate summary released on Wednesday, NOAA’s National Centers for Environmental Information (NCEI) calculated that the average global temperature across both land and ocean surfaces for 2016 was 1.69°F (0.94°C) above the 20th-century average of 13.9°C (57.0°F). This made 2016 the warmest calendar year on record, coming in 0.07°F (0.04°C) ahead of the record set just last year. Using a slightly different technique, NASA also confirmed that 2016 was the warmest year in this 136-year period.

Last year was also the warmest on record for satellite-based estimates of temperature through the lowest five miles of the atmosphere, as calculated by the University of Alabama in Huntsville (UAH). In the UAH dataset, 2016 came in just 0.02°C (0.04°F) ahead of 1998. Because these calculations are indirect, large-scale estimates of temperature well above ground level, derived from satellite data, they need not correspond to trends in direct ground-based measurements of surface temperature.

The second year of a major El Niño tends to warm the global atmosphere even more than the first, as the atmosphere gradually adjusts to the ocean-surface warming. This gave 2016 a very good shot at breaking the global temperature record that was just set by 2015, which in turn beat out 2014. The absence of a strong El Niño heading into 2017 tells us that the coming year, while expected to be very warm by 20th-century standards, is unlikely to continue the remarkable three-year string of consecutive global heat records set by 2014, 2015, and 2016.

It’s worth noting that only about 0.2°C of last year’s departure from long-term average temperature can be explained by El Niño, especially given that the tropical Pacific transitioned to a weak La Nina by late 2016. The fact that 2016 was still the warmest year on record can mostly be attributed to the steady build-up of heat-trapping greenhouse gases due to human activities.


Figure 1. Departure from the 20th-century average for the global January-through-December temperature for the years 1880 - 2016. Last year saw the warmest temperatures on record, following previous global record highs in 2014 and 2015. Image credit: NOAA/National Centers for Environmental Information (NCEI).

Third warmest December on record
December 2016 was Earth's third warmest December since record keeping began in 1880, reported NOAA/NCEI on Wednesday. December 2016 was 0.79°C (1.42°F) warmer than the 20th-century December average, but 0.33°C (0.60°F) cooler than the record warmth of 2015. NASA reported that December 2016 was the second warmest December in its database, behind December 2015 and just ahead of December 2014. The difference between the two data sets is, in large part, due to how they handle the data-sparse areas in the Arctic, which was record warm in December. NOAA does not include most of the Arctic in their global analysis, while NASA does.


Figure 2. Departure of temperature from average by region for December 2016, the third warmest December for the globe since record keeping began in 1880. Record warmth was observed across parts of southern Mexico and Central America, western Norway, parts of sub-Saharan Africa, and parts of the Middle East and southern Asia along a belt from Iran to eastern China. Cooler-than-average conditions were observed across the northwest United States, southeast Europe, and western Russia. Image credit: NOAA National Centers for Environmental Information (NCEI).

As noted above, a weak La Niña event is now under way in the eastern tropical Pacific, and the cool waters present there have helped cool the planet slightly below the record warm levels observed during the strong El Niño event that ended in May 2016. The fact that December 2016 was still among the three warmest Decembers on record despite the presence of La Niña can mostly be attributed to the steady build-up of heat-trapping greenhouse gases due to human activities.

Ocean-only, land-only, and lower atmosphere temperatures in December
Ocean-only temperatures this December were the fourth warmest on record, while land-only temperatures were the sixth warmest on record. (Since most of Earth’s surface is covered by ocean, the land-plus-ocean reading is dominated by the ocean-only temperatures.) For the lowest 8 km of the atmosphere, global satellite-measured temperatures in December 2016 were the third warmest in the 38-year record, behind December 2016 and 1997, according to the University of Alabama in Huntsville.

Arctic sea ice hits its second lowest December extent on record
December 2016 Arctic sea ice extent was the second lowest in the 38-year satellite record, according to the National Snow and Ice Data Center (NSIDC). Arctic sea ice set new records for low extent in 2016 for the months of January, February, April, May, June, October,and November. Ice extent has also been very low in the Antarctic, where record lows were set in both November and December. As we discussed in a November post, sea ice extents in the Arctic and Antarctic vary through mostly independent processes, so the simultaneous record lows in recent months are somewhat unexpected.


Figure 3. Daily mean temperatures by Julian day for 2016 over the Arctic north of 80°N, as compiled by the Danish Meteorological Institute (DMI). Temperatures for 2016 (red line) are compared to the long-term averages (green line.) Temperatures in October, November, and December were 5 -  20°C (9 - 36°F) above average. This is by far the warmest multi-month anomaly measured since DMI began tracking Arctic temperatures in 1956. According to the 2016 Arctic Report Card, issued last week, the average surface air temperature of the Arctic for the year ending September 2016 was by far the highest since 1900. Temperatures in the Arctic are continuing to warm at roughly twice the pace of the global average, which is an expected outcome of climate change caused by human-produced greenhouse gases.

No billion-dollar weather disasters in December 2016
According to the December 2016 Catastrophe Report from insurance broker Aon Benfield, no billion-dollar weather-related disasters hit the planet in December. During 2016, there were 31 billion-dollar weather disasters globally. This is the fourth greatest number of such disasters in any year since 1990. See our post from January 17 for a full summary.

Notable global heat and cold marks set in December 2016
Hottest temperature in the Northern Hemisphere: 42.8°C (109.0°F) at Diourbel, Senegal, 2 December
Coldest temperature in the Northern Hemisphere: -56.9°C (-70.4°F) at Suhana, Russia, 31 December
Hottest temperature in the Southern Hemisphere: 46.3°C (115.3°F) at Birdsville Airport, Australia, 2 December
Coldest temperature in the Southern Hemisphere: -44.0°C (-77.1°F) at Dome A, Antarctica, 2 December
(Courtesy of Maximiliano Herrera.)

Major weather stations that set (not tied) new all-time heat or cold records in December 2016 (Courtesy of Maximiliano Herrera)
Santiago (Chile) max. 37.3°C, 14 December
Santiago Airport (Chile) max. 37.0°C, 14 December
Rapel (Chile) max. 36.4°C, 14 December
Oruro (Bolivia) max. 27.6°C, 18 December
Big Bend (Swaziland) max. 46.1°C, 22 December
Vuvulane (Swaziland) max. 44.3°C, 22 December
Ambon (Indonesia) max. 36.4°C, 22 December
Mouyondzi (Congo Brazzaville) max. 36.4°C, 22 December
Luanda (Angola) max. 36.9°C, 22 December

More nations set all-time highs in 2016 than in any other year
From January through December 31, 2016, a total of 22 nations or territories tied or set all-time records for their hottest temperature in recorded history.  This breaks the record of eighteen all-time heat records in 2010 for the greatest number of such records set in one year. Just one nation or territory—Hong Kong—set an all-time cold temperature record in 2016. "All-time" record here refers to the warmest or coldest temperature ever reliably reported in a nation or territory. The period of record varies from country to country and station to station, but it is typically a few decades to a century or more. Most nations do not maintain official databases of extreme temperature records, so the national temperature records reported here are in many cases not official. Our data source is international weather records researcher Maximiliano Herrera, one of the world's top climatologists, who maintains a comprehensive list of extreme temperature records for every nation in the world on his website. If you reproduce this list of extremes, please cite Maximiliano Herrera as the primary source of the weather records. Here are 2016's all-time heat and cold records:

The Comoros: December 22, 2016, 35.6°C (96.1°F) at Hahaya Airport (tie).
French Guiana : September 27, 2016, 38.0°C (100.3°F) at Saint Laurent du Moroni.
The Marshall Islands: August 24, 2016, 35.6°C (96.1°F) at Utirik Atoll.
The Cayman Islands (United Kingdom territory) : August 21, 2016, 34.9°C (94.8°F) at Owen International Airport (tie).
The British Virgin Islands [United Kingdom territory]: July 22, 2016, 35.0°C (95.0°F] at Terrance B. Lettsome International Airport.
Iraq: July 22, 2016, 53.9°C (129.0°F) at Basrah.
Iran: July 22, 2016, 53.0°C (127.4°F) at Delhoran (tie).
Kuwait : July 21, 2016, when the mercury hit 54.0°C (129.2°F) at Mitribah.
Guernsey (United Kingdom territory): July 19, 2016, 35.0°C (95°F) at the small island of Alderney (tie).
Hong Kong Territory (China): July 9, 2016, 37.9°C (100.2°F) at Happy Valley (tie).
Niger: June 8, 2016, 49.0°C (120.2°F) at Bilma.
Palau: June 8, 2016, 34.4°C (93.9°F) at Koror AWS (tie).
India : May 19, 2016, 51.0°C (123.8°F) at Phalodi.
Maldives: April 30, 2016, 35.0°C (95.0°F) at Hanimaadhoo.
Thailand: April 28, 2016, 44.6°C (112.3°F) at Mae Hong Son.
Cambodia: April 15, 2016, 42.6°C (108.7°F) at Preah Vihea.
Burkina Faso: April 13, 2016, 47.5°C (117.5°F) at Dori.
Laos: April 12, 2016, 42.3°C (108.1°F) at Seno.
Vanuatu in the South Pacific: February 8, 2016, 36.2°C (97.2°F) at Lamap Malekula.
Tonga: February 1, 2016, 35.5°C (95.9°F) at Niuafoou.
Wallis and Futuna Territory (France): January 10, 35.8°C (96.4°F) at Futuna Airport.
Botswana: January 7, 2016, 43.8°C (110.8°F) at Maun.

Hong Kong Territory (China) set its all-time coldest mark on January 24, 2016, -6.0°C (21.2°F) at Tai Mo Shan (elevation 950 meters.) Tai Mo Shan has a period of record going back to 1996; the coldest temperature near sea level since record keeping began at the Hong Kong Observatory in 1884 was 0°C (32°F) on January 18, 1893.

Monthly national and territorial records of highest temperature beaten or tied (excluding records valid for any month):  145
Monthly national and territorial records of lowest temperature beaten or tied  (excluding records valid for any month):  4

Station records (not including tied records)
Number of stations that beat their all-time highest temperature: 316
Number of stations that beat their all-time lowest temperature: 21

Worldwide extreme temperatures for 2016
Highest in Northern Hemisphere:  54.0°C (129.2°F) at Mitribah, Kuwait, on July 21
Lowest in Northern Hemisphere:  –61.3°C (–78.3°F) at Geo Summit, Greenland, on February 11

Highest in Southern Hemisphere:  48.6°C (119.5°F) at Augrabies Falls, South Africa, on January 5
Lowest in Southern Hemisphere:  –82.4°C (–116.3°F) at Concordia, Antarctica, on July 8

Global, hemispheric and continental records for 2016
Highest temperature ever recorded in February in Northern Hemisphere:  45.0°C at Nguigmi (Niger) on February 26 (tie)
Highest reliable minimum temperature ever recorded in Africa:  37.5°C at Yelimane (Mali) on May 1
Highest minimum temperature ever recorded in May in Australia+Oceania:  29.6°C at Troughton Island (Australia) on May 2
Highest temperature ever recorded in May in South America:  41.4°C at Valledupar, Colombia, on May 23
Highest temperature ever recorded in May in Antarctica: 17.2°C at Esperanza on May 26
Highest minimum temperature ever recorded in Antarctica: 8.8°C at Esperanza on May 27
Highest temperature ever recorded in June in Southern Hemisphere:  39.5°C at Picos, Brazil, on June 4
Highest minimum temperature ever recorded in June in Australia+Oceania:  28.8°C at Troughton Island, Australia, on June 6
Highest temperature ever recorded in June in Australian+Oceania:  37.9°C at Bradshaw, Australia, on June 7
Highest temperature ever recorded in Asia:  54.0°C at Mitribah, Kuwait, on July 21
Highest temperature ever recorded in July in Australia+Oceania:  38.3°C at Kalumburu, Australia, on July 24
Lowest temperature ever recorded in Northern Hemisphere in July:  –30.5°C at Geo Summit, Greenland, on July 31
Highest minimum temperature ever recorded in the world in August:  40.8°C at Delhoran, Iran, on August 2
Highest temperature ever recorded in September in Asia:  51.2°C at Mitribah, Kuwait, on September 4
Highest temperature ever recorded in September in Europe:  45.7°C at Montoro, Spain, on September 6
Highest minimum temperature ever recorded in September in Australia+Oceania:  30.0°C at Warmun, Australia, on September 28
Lowest temperature ever recorded in October in Africa:  –10.5°C at Buffelsfontein, South Africa, on October 5
Highest temperature ever recorded in December in the Northern Hemisphere:  42.8°C in Diourbel, Senegal, on December 2

The reading of 54°C at Mitribah, Kuwait, on July 21 ties the highest global temperature that has been measured reliably by contemporary standards. See the October blog post from WU weather historian Christopher Burt for a discussion of the WMO world heat record of 134°F (56.7°C), recorded in Death Valley, California, on July 10, 1913. For a variety of reasons, Burt concluded, “the best explanation for the record high report(s) in July 1913 is observer error.”

We'll be back with a new post on Friday.

Jeff Masters and Bob Henson