El Niño is over, but has left its mark across the world
The 2015-16 El Niño has likely reached its end. Tropical Pacific Ocean temperatures, trade winds, cloud and pressure patterns have all dropped back to near normal, although clearly the event's impacts around the globe are still being felt.
Recent changes in Pacific Ocean temperatures have been comparable to the decline seen at the end of the 1998 El Niño, although temperatures remain warmer than at the end of the most recent El Niño in 2010. Models suggest that ocean cooling will continue, with little chance of a return to El Niño levels in the immediate future.
The observed and forecast decline of the 2015-16 El Niño, compared to the record event of 1997-98 and the previous El Niño in 2009-10
The 2015-16 El Niño will go down as one of the three strongest El Niño events since 1950. Every El Niño is different, but typically the stronger the event, the greater its global impact. The 2015-16 El Niño was no exception, with wide-ranging effects felt around the world.
El Niño also added to the globe's warming trend, making 2015 the world's hottest calendar year on record. Early indications are that 2016 could be hotter still.
So as El Niño fades, let's take stock of its impacts worldwide.
Typical impacts of El Niño across the globe.
El Niño is often, but not always, associated with drought in Australia. But the drying influence of the 2015-16 El Niño was initially tempered somewhat by very warm temperatures in the Indian Ocean. From April to August, above-average rainfall fell over parts of inland Western Australia, New South Wales and eastern Victoria.
But by spring, the Indian Ocean was helping El Niño, resulting in Australia's third-driest spring on record, limiting growth at the end of the cropping season. A record early heatwave in October further reduced crop production in the Murray-Darling Basin.
However, the lack of heavy rains in the north and west meant reduced downtime for mining.
The northern wet season produced a record-low three tropical cyclones in the Australian region. The previous record was five, which happened in 1987-88 and again in 2006-07 - both El Niño years.
Fewer clouds and less tropical rain contributed to the most severe coral bleaching event on record for the Great Barrier Reef.
The combination of heat and low rainfall brought a very early start to the fire season, with more than 70 fires burning in Victoria and around 55 fires in Tasmania during October. Dry conditions in Tasmania also resulted in hundreds of fires being started by dry lightning in mid-January 2016. The fires damaged large areas of the Tasmanian Wilderness World Heritage Area, including areas of rainforest and bogs, which may not have seen fire for centuries.
The Pacific Region
In Papua New Guinea, drought and frost led to crop failures and food shortages. Staple sweet potato crops in the highlands were severely damaged by August frosts - the result of El Niño reducing night-time cloud cover - which also destroyed wild plants that are usually eaten as a backup source of food.
Vanuatu, Fiji, the Solomon Islands, Samoa and Tonga experienced worsening drought. Islands closer to the Equator such as Kiribati and Tuvalu had intense rain causing flooding, as well as higher sea levels due to warmer waters and weaker trade winds.
In the Philippines, drought was declared in 85% of provinces. Indonesia experienced its worst drought in 18 years. Forest fires caused poor air quality over vast neighbouring areas including Singapore, Malaysia, southern Thailand and the southern Philippines.
In the Mekong Basin, delayed monsoon rains reduced rice production, with significant reductions in Vietnam. In Thailand, severe water shortages led to water rationing and delayed rice planting. The Thai government lowered its forecast for rice exports by two million tonnes. This led to some African countries increasing their imports, fearing a price rise.
Palm oil prices rose as supplies became limited due to drought in Malaysia and Indonesia. In April 2016, a heatwave set national temperature records for Thailand, Laos and Cambodia.
Northern parts of China experienced drought in 2015. Heavy rainfall in southern China persisted through the second half of 2015, with flooding and landslides recorded along the Yangtze River Valley. China's December-to-February rainfall was approximately 50% above normal. In May 2016, heavy rain caused flooding and landslides in China's Guangdong province.
In India, below-average monsoon rains in June to September led to reduced rice, corn, cotton and sugar output in 2015. Below-average rainfall between October and December also affected India's wheat harvest. Major water shortages emerged in some areas, including Mumbai - the result of two years of failed rains.
Indian Premier League cricket matches were relocated from Mumbai, Pune and Nagpur due to water restrictions. Record heat affected the north and west of the country in May, setting a new national record of 51℃ in Phalodi.
Conversely, some southern parts of India had exceptionally wet conditions, with record-breaking rains and widespread flooding in Chennai in November and December. The city received over 300mm of rainfall on December 1, 2015; the wettest day in more than a century.
South and Central America
Peru experienced widespread flooding and mudslides in early 2016, with heavy rain leaving more than 5,000 people homeless. In Ecuador, flooding and landslides damaged properties and affected shrimp production.
More than 150,000 people were evacuated from flooded areas in Paraguay, Uruguay, Brazil, and Argentina in December 2015. Some experts have linked El Niño flooding to outbreaks of mosquito-borne diseases such as Zika virus.
In January 2016, Argentina experienced its worst locust plague since 1954, following heavy rains and warm temperatures. Heavy rains returned to Argentina and Paraguay in April 2016, causing large agricultural losses.
In contrast, Colombia experienced drought and forest fires, which caused severe damage to crops and pushed up food prices, leading to malnutrition in some areas. In November 2015, the United Nations warned that 2.3 million people would need food aid in Central America.
The Caribbean also experienced drought; Cuba had its most severe dry season in 115 years; Barbados, Dominica, the Virgin Islands, Puerto Rico, Antigua, Barbuda and Saint Lucia experienced water shortages, with the latter declaring a national emergency. The Dominican Republic experienced serious agricultural losses.
Brazil had a particularly high number of forest fires during 2015, exacerbated by ongoing drought conditions in the Amazon region. Drought in Brazil and Colombia (and Indonesia) meant coffee prices soared as dry conditions affected all the major coffee-producing countries.
In contrast, excess rain in northeast Brazil flooded crops, leading to rises in the sugar price worldwide.
In California, many hoped that El Niño would bring relief from five years of drought. But despite some regions getting heavy rain more typical of El Niño, leading to mudslides, El Niño failed to end the long-term dry.
In the southeast and south-central United States, rainfall was above normal. Major flooding occurred along the Mississippi River. Missouri received three times its normal rainfall during November and December 2015.
Warmer-than-average sea surface temperatures offshore meant warm water species such as sea snakes, red tuna crabs and hammerhead sharks were found on Californian beaches.
Drought meant that South African food production was around six million tonnes below normal levels - the lowest since 1995.
In Zimbabwe, Malawi and Mozambique, maize prices were at least 50% higher than usual, with drought unlikely to break until rains in summer 2016-17. In the driest areas of Zimbabwe, more than 75% of crops were lost. In May 2016, Zimbabwean national parks put wildlife up for sale in a bid to save animals from drought.
The cost of chocolate hit a four-year high as a result of drought and lost production in the world's major cocoa producer, Ivory Coast.
Drought also affected Ethiopia, Somalia, Swaziland, Zambia and parts of Madagascar, with more than 10 million Ethiopians in need of food aid.
In December 2015, Rift Valley fever was reported in East Africa. The disease is associated with heavy rainfall providing a fertile breeding ground for the mosquitoes that carry the virus.
In Tanzania, heavy rain destroyed crops and food reserves, while in Kenya heavy rains aggravated cholera outbreaks. In May 2016, landslides in Rwanda cost many lives and heavy rains damaged infrastructure and hundreds of homes.
For information on the current and forecast state of ENSO, keep an eye on the Bureau's ENSO Wrap-Up.
Alison Cook, Climatologist, Australian Bureau of Meteorology; Andrew B. Watkins, Manager of Climate Prediction Services, Australian Bureau of Meteorology; Blair Trewin, Climatologist, National Climate Centre, Australian Bureau of Meteorology, and Catherine Ganter, Senior Climatologist, Australian Bureau of Meteorology