Earth's Top Ten Weather/Climate Events of 2015

1) Earth's Warmest Year on Record
The final numbers are not in yet, but 2015 is virtually certain to beat 2014's record as the planet's warmest year since record keeping began in 1880. Nine of the first eleven months of 2015 set new all-time monthly records for global heat in the NOAA database, and the two most recent months that have been catalogued--October and November 2015--had by far the warmest departures from average of any months on record. The new record was caused by the long-term warming of the planet due to human-caused emissions of heat-trapping gases like carbon dioxide, combined with a extra bump in temperature due to the strongest El Niño event ever recorded in the Eastern Pacific. Record warm ocean temperatures in the tropics in 2015 led to a global coral bleaching event, which is expected to cause a loss of 10 - 20% of all coral worldwide. The lingering warmth from El Niño makes 2016 a good bet to exceed even 2015's warmth.


Figure 1. Departure of the global surface temperature from average for the period January - November, for all years from 1880 to 2015. The year 2015 will easily beat 2014 as the warmest year on record. Image credit: NOAA.

2) Earth's Strongest El Niño Event on Record
A potent El Niño event in the Eastern Pacific that crossed the threshold into the "strong" category in early July peaked in mid-November with the highest weekly heat ever observed in the equatorial Eastern Pacific waters. Sea-surface temperatures (SSTs) in the Pacific’s Niño3.4 region, between 90°W and 160°E longitude and 5° north/south latitude, are considered the benchmark for rating the strength of an El Niño event. The weekly departure of SST from average in this region hit +3.1°C (5.6°F), NOAA announced in their November 23 El Niño update. This exceeds the previous 1-week record warmth in the equatorial Pacific of 2.8°C above average set during the week of November 26, 1997; accurate El Niño records extend back to 1950. The standard measure for the strength of an El Niño event is the three-month average Niño 3.4 departure of SST from average, and the El Niño of 2015 is tied with 1997 for the strongest on record. The October-November-December three-month average Niño 3.4 SSTs were 2.3°C above average in both 2015 and 1997. The 2015 record-strength El Nino was helped along in mid-March 2015 by the strongest Madden Julian Oscillation (MJO) event ever recorded (the MJO is a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days.) The Wheeler-Hendon MJO index hit 4.67 on March 16, 2015, beating the old record of 4.01 set on February 14, 1985. MJO record keeping began in 1974 (with no data available from 3/17/1978-12/31/1978 due to satellite problems). Thanks go to CSU's Phil Klotzbach for stats on the MJO record.



Figure 2. Sea-surface temperatures (SSTs) in the Pacific’s Niño3.4 region, between 90°W and 160°E longitude and 5° north/south latitude, are considered the benchmark for rating the strength of an El Niño event. The weekly departure of SST from average in this region hit +3.1°C (5.6°F) in mid-November 2015, beating the previous record of +2.8°C set during November 1997 during that year's super-El Niño. Image credit: Jan Null Golden Gate Weather, via Twitter.

3) Earth's Strongest Western Hemisphere Hurricane Ever Measured: Hurricane Patricia
Record-warm ocean waters helped Hurricane Patricia explode into a Category 5 storm with 200 mph sustained surface winds and a central pressure of 879 mb off the Pacific coast of Mexico on October 23, 2015, making Patricia the most intense hurricane ever observed in the Western Hemisphere (the Eastern Hemisphere has had several more intense typhoons, however, with Super Typhoon Tip of 1979 holding the all-time record with an 870 mb central pressure.) Patricia made landfall in an relatively unpopulated area near Cuixmala in Southwest Mexico on October 23 as a Category 5 storm with 165 mph winds, killing fourteen and doing $300 million in damage. Patricia helped bring the Accumulated Cyclone Energy (ACE) in the Northeast Pacific (east of the Date Line) to its second highest value on record, just behind 1992 (288 in 2015 vs. 292 in 1992). The Northeast Pacific (east of the Date Line) also had more major hurricanes (11) than any other year on record, breaking the old record of 10 set in 1992. Thanks go to Dr. Phil Klotzbach of Colorado State University for these last two stats.


Figure 3. Hurricane Patricia as seen by the MODIS instrument on NASA's Terra spacecraft at 1:30 pm EDT October 23, 2015. At the time, Patricia was the most intense hurricane ever observed in the Western Hemisphere, with 200 mph sustained surface winds and a central pressure of 879 mb. Image credit: NASA.

4) Indonesia's $16 Billion Fires: Most Expensive Disaster of 2015
Earth's most expensive weather-related disaster of 2015--and the most expensive disaster in Indonesia's history--is still underway in that nation, where massive clouds of smoke from agricultural fires have choked the lungs of tens of millions of people for months. The World Bank estimated the smoke will cost $16.1 billion in agriculture production, forest degradation, health, transportation and tourism. The disaster may also be the deadliest disaster of 2015, depending upon how one treats the difficult task of determining air pollution deaths. Over 10,000 adults are likely to die from pollution from the fires, judging by the results of a 2013 study in Nature Climate Change by Marlier et al., El Niño and health risks from landscape fire emissions in Southeast Asia. Thanks go to Steve Bowen of insurance broker Aon Benfield for the World Bank damage estimate.


Figure 4. Buildings (background) along Shenton way business district are blanketed with thick smog in Singapore on September 24, 2015. Singapore's air quality reached 'very unhealthy' levels on September 24, forcing schools to close, as thick smog from agricultural fires in Indonesia's neighboring Sumatra Island choked the city-state. Image credit: ROSLAN RAHMAN/AFP/Getty Images.

5) Deadliest Weather Disasters of 2015: Heat Waves in Indian, Pakistan, and Europe
Earth's hottest year in recorded history brought three significant heat waves responsible for thousands of deaths. The worst was India's horrid May heat wave, which killed 2,500--the second deadliest in India's recorded history, and the fifth deadliest in world history. According to statistics from EM-DAT, the International Disaster Database, India's only deadlier heat wave was in 1998, when 2,541 died. A separate heat wave in June 2015 in Pakistan killed 1,229, ranking as the world's eighth deadliest heat wave in recorded history. Record summer heat in Europe killed hundreds more. Note, though, that death tolls from heat waves are very difficult to estimate, since excess heat is typically not listed as the primary cause of death in cases where the victim has a pre-existing condition such as heart or lung disease. Below is the list of top ten deadliest heat waves in world history as compiled by EM-DAT, the International Disaster Database, which uses direct deaths for their statistics, and not excess mortality. Included in bold are two heat waves in 2015.

The 10 Deadliest Heat Waves in World History
1) Europe, 2003: 71,310
2) Russia, 2010: 55,736
3) Europe, 2006: 3,418
4) India, 1998: 2,541
5) India, 2015: 2,500
6) U.S. and Canada, 1936: 1,693
7) U.S., 1980: 1,260
8) Pakistan, 2015: 1,229
9) India, 2003: 1,210
10) India, 2002: 1,030


Figure 5. A young Indian child pours water on himself as he tries to cool himself off in New Delhi on May 28, 2015. Image credit: MONEY SHARMA/AFP/Getty Images.

6) Deadliest Storm of 2015: Floods in South India and Sri Lanka Kill 328
Five weeks of frequent torrential monsoon rainfall fed by record-warm ocean waters during November and early December inundated southern India and Sri Lanka. The resulting floods killed 328 people and did at least $3 billion in damage. Hardest hit was Chennai, an urban area of more than 9 million people that ranks as the largest in South India and among the world’s 40 largest metro areas. Parts of Chennai spent days inundated by as much as eight feet of polluted water, with widespread power outages exacerbating the crisis. Chennai recorded 1218.6 mm (47.98”) of rain in November, the highest observed for any November in more than 100 years of record-keeping. Then, on December 1-2, a total of 345 mm (13.58”) fell in 24 hours, which smashed the city’s all-time 24-hour record rainfall of 261.6 mm on December 10, 1901. Chennai’s airport was closed for four days in early December, with some 4000 people and dozens of aircraft stranded. At one point, all runways were under water.


Figure 6. India's flooded Chennai airport on Thursday, December 2, 2015. Image credit: Atul Yadav/ Press Trust of India via AP.

7) Wild Christmas Week Flooding and Storms in the U.S.
Record atmospheric moisture over the southern U.S. during Christmas week helped fuel record rains and two deadly tornado outbreaks between December 23 - 28. At least 59 people were killed by tornadoes, flooding, and associated severe weather in the outbreak, making it our nation's deadliest weather event of 2015. The heavy rains brought the Mississippi River just south of St. Louis in early January to its highest level since records began in 1844, beating the great flood of 1993. We expect record floods in the spring from the combined effect of snow melt and heavy rains, but to get one in the winter when the moisture-carrying capacity of the atmosphere is usually at a minimum and there is no contribution to the flood from snow melt is off-the-charts freakish. During the insane rains that deluged the Mississippi Valley during the week of Christmas, record levels of atmospheric moisture were observed. This moisture largely came from the southern Gulf of Mexico, where ocean temperatures were at record or near-record warm levels for so late in the year. These waters would not have been so warm without global warming helping make 2015 the warmest year on record globally.


Figure 7. Damage from the tornado that struck Rowlett, Texas, on Saturday evening, December 26, 2015. The tornado was rated EF4, and killed eight people in Garland, Texas. Image credit: NWS/Fort Worth.

8) Tropical Cyclone Pam
A tropical cyclone catastrophe of nearly unprecedented dimensions affected the unlucky South Pacific island nation of Vanuatu, after a Friday the 13th strike in March by Category 5 Tropical Cyclone Pam. At its peak, Pam's 165 mph winds made it one of only ten Category 5 storms ever rated by the Joint Typhoon Warning Center (JTWC) in the waters east of Australia. The official tropical cyclone warning center for the area, the Fiji Meteorological Service, estimated that Pam's central pressure bottomed out at 896 mb, making it the second most intense tropical cyclone in the South Pacific basin after Cyclone Zoe of 2002. Pam was at its peak strength, with 165-mph Category 5 winds, when it passed over several small Vanuatu Islands to the north of Efate Island, Vanuatu's most populous island (population 66,000.) Pam is one of only two Category 5 cyclones in recorded history to make landfall on a populated island in the waters east of Australia. The only other Category 5 landfall event among the nine other Category 5 storms to affect these waters since 1970 was by the strongest tropical cyclone on record in the basin, Cyclone Zoe of 2002. Pam killed 16 people and did $433 million in damage, making it by far the costliest disaster in Vanuatu's history. According to EM-DAT, the international disaster database, the only comparable disaster in Vanuatu's history occurred in January 1985 when twin Category 3 storms--Eric and Nigel--battered the nation, affecting 118,000 people and doing $173 million in damage.


Figure 8. Tropical Cyclone Pam approaching Vanuatu's capital city of Port Vila on Efate Island, as seen by the MODIS instrument on the Aqua satellite at 10:20 pm EDT March 12, 2015. At the time, Pam was a Category 5 storm with 160 mph winds. Image credit: NASA.

9) Hurricane Joaquin
Hurricane Joaquin was the strongest Atlantic hurricane since 2007, topping out just below Category 5 strength on October 3 with 155 mph winds. Joaquin was the second deadliest and second most damaging Atlantic named storm of 2015, causing $100 million in damage in the Central Bahamas, where it lingered for several days. Joaquin's death toll was 35, with 33 of these deaths occurring from the sinking of the ill-fated cargo ship El Faro. Although Joaquin tracked far to the east of the United States, a non-tropical low over the Southeast tapped into the hurricane's moisture, causing record-shattering rains and flooding across North and South Carolina. Several areas of South Carolina saw accumulations exceeding the threshold for a 1-in-1,000-year event. The subsequent floods inundated large areas of the state, killing 21 people and causing over $2 billion in damage.


Figure 9. Hurricane Joaquin as seen by the GOES-East satellite at 7:45 am EDT October 1, 2015. At the time, Joaquin was an intensifying Category 2 storm with 110 mph winds. The last position of the cargo ship El Faro, in the northwestern eyewall of Joaquin, is shown. Image credit: United States Navy and NOAA.

10) Record Central Pacific Hurricane Activity
Record warm ocean temperatures and record low wind shear in the Central Pacific (140-180°W) helped fuel a wildly active hurricane season. A few of the notable records set, courtesy of Dr. Phil Klotzbach of Colorado State University:

- 8 named storms formed in the North Central Pacific, shattering the old record of 4 named storms set in 1982
- 14 named storms, 8 hurricanes and 5 major hurricanes either formed or tracked into the North Central Pacific from the Northeast Pacific in 2015. This broke the old records of 10 named storms (set in 1982 and 1997), 5 hurricanes (set in 1982 and 1994) and 3 major hurricanes (set in 1994).
- 127 Accumulated Cyclone Energy (ACE) units were generated in the North Central Pacific, breaking old ACE record of 107 set in 1994.
- Record high SSTs and record low wind shear (since ~1980) were recorded when averaged from July-October across the North Central Pacific Main Development Region (7.5-20°N, 180- 140°W)


Figure 10. A mosaic of infrared satellite images from geostationary satellites showing all 15 tropical storms to reach or form in the Central Pacific basin in 2015. The images were obtained through the Naval Research Lab's Online archive. Miraculously, the Hawaiian Islands (outlined in aqua) seemed to have a zone of exclusion around them, and all the storms missed the islands. In 2014, Tropical Storm Iselle hit the Big Island and two other hurricanes came within 200 miles of the islands, and the busy Hawaiian hurricane season of 2014 was linked to climate change in a 2015 Bulletin of the American Meteorological Society annual attribution report on how extreme events may be influenced by climate change. Image credit: Kevin Kodama/National Weather Service Honolulu Office. H/T to wxhisft.com, where I originally saw this image posted.

The next post will be Thursday afternoon, when stats from NOAA summarizing the 2015 weather year in the U.S. will be available.

Jeff Masters (with Bob Henson helping out on the India floods section)