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95-755: Kevin Edward Trenberth CNZM (born 8 November 1944 in Christchurch , New Zealand) worked as a climate scientist in the Climate Analysis Section at the US National Center for Atmospheric Research (NCAR). He was a lead author of the 1995, 2001 and 2007 IPCC assessment reports . He also played major roles in the World Climate Research Programme (WCRP), for example in its Tropical Oceans Global Atmosphere program (TOGA),

190-758: A Commonwealth realm are given "Honorary" membership; if they subsequently adopt citizenship of a Commonwealth realm they are eligible for Additional membership. There is also a Secretary and Registrar (the Clerk of the Executive Council) and a Herald (the New Zealand Herald of Arms) of the Order. There also exist miniatures and lapel badges of the five levels of the New Zealand Order of Merit. Knight/Dames Grand Companion and Knight/Dames Companion are entitled to use

285-508: A Dame Grand Companion, formally receiving investiture in 2024 from Prince William . El Ni%C3%B1o-Southern Oscillation El Niño is associated with higher than normal air sea level pressure over Indonesia, Australia and across the Indian Ocean to the Atlantic . La Niña has roughly the reverse pattern: high pressure over the central and eastern Pacific and lower pressure through much of

380-585: A Monarchy". The issue of titular honours would appear whenever honours were mentioned. In the lead up to the 2005 general election , Leader of the Opposition Don Brash suggested that should a National-led government be elected, he would reverse Labour's changes and re-introduce knighthoods. In 2009, Prime Minister John Key (later to become a Knight Grand Companion himself) restored the honours to their pre-April 2000 state. Principal Companions and Distinguished Companions (85 people in total) were given

475-570: A change of surface winds over the Pacific which had caused ocean heat to penetrate below 700m depth and had contributed to the apparent global warming hiatus in surface temperatures during the previous decade. In an interview, Trenberth said, "The planet is warming", but "the warmth just isn't being manifested at the surface." He said his research showed that there had been a significant increase in deep ocean absorption of heat , particularly after 1998. He told Nature that "The 1997 to '98 El Niño event

570-556: A cooler West Pacific and a warmer East Pacific, leading to a shift of cloudiness and rainfall towards the East Pacific. This situation is called El Niño. The opposite occurs if trade winds are stronger than average, leading to a warmer West Pacific and a cooler East Pacific. This situation is called La Niña and is associated with increased cloudiness and rainfall over the West Pacific. The close relationship between ocean temperatures and

665-531: A decrease in the strength of the Pacific trade winds , and a reduction in rainfall over eastern and northern Australia. La Niña episodes are defined as sustained cooling of the central and eastern tropical Pacific Ocean, thus resulting in an increase in the strength of the Pacific trade winds , and the opposite effects in Australia when compared to El Niño. Although the Southern Oscillation Index has

760-490: A knighthood. Appointments continued when Labour returned to government in 2017 as the Sixth Labour Government . The 2018 New Year Honours included seven knights and dames. The government did not comment on its position regarding knighthoods and damehoods, but Prime Minister Jacinda Ardern did specifically congratulate two women on becoming Dames Companion. On leaving office in 2023, Ardern accepted appointment as

855-485: A larger EP ENSO occurrence, or even displaying opposite conditions from the observed ones in the other Niño regions when accompanied by Modoki variations. ENSO Costero events usually present more localized effects, with warm phases leading to increased rainfall over the coast of Ecuador, northern Peru and the Amazon rainforest , and increased temperatures over the northern Chilean coast, and cold phases leading to droughts on

950-533: A long station record going back to the 1800s, its reliability is limited due to the latitudes of both Darwin and Tahiti being well south of the Equator, so that the surface air pressure at both locations is less directly related to ENSO. To overcome this effect, a new index was created, named the Equatorial Southern Oscillation Index (EQSOI). To generate this index, two new regions, centered on

1045-411: A negative SSH anomaly (lowered sea level) via contraction. The El Niño–Southern Oscillation is a single climate phenomenon that quasi-periodically fluctuates between three phases: Neutral, La Niña or El Niño. La Niña and El Niño are opposite phases which require certain changes to take place in both the ocean and the atmosphere before an event is declared. The cool phase of ENSO is La Niña, with SST in

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1140-641: A publication by Kevin Trenberth and Dennis J. Shea in 2006. Trenberth further explained the concept to a broader audience in an article on hurricanes and climate change in Scientific American in 2007. It has the short and snappy title: "Warmer Oceans, Stronger Hurricanes". In a 2013 scientific paper in Geophysical Research Letters , Trenberth and co-authors presented an observation-based reanalysis of global ocean temperatures. This proposed that

1235-517: A quarter of the planet, and particularly in the form of temperature at the ocean surface, can have a significant effect on weather across the entire planet. Tropical instability waves visible on sea surface temperature maps, showing a tongue of colder water, are often present during neutral or La Niña conditions. La Niña is a complex weather pattern that occurs every few years, often persisting for longer than five months. El Niño and La Niña can be indicators of weather changes across

1330-486: A recent hiatus in upper- ocean warming after 2004 had seen the long-term increase interrupted by sharp cooling events due to volcanic eruptions and El Niño . Despite this, ocean warming had continued below the 700   m depth. In a second 2013 paper, Trenberth and Fasullo discussed the effect of the 1999 change from a positive to negative phase of the Pacific Decadal Oscillation . This was associated with

1425-524: A representation of the Collar of the Order around his/her shield. The following contains the names of the small number of living Distinguished Companions (DCNZM) who chose not to convert their appointment to a Knight or Dame Companion, and thus not to accept the respective appellation of "Sir" or "Dame". The majority of those affected chose the aforereferenced appellations. After initially declining redesignation in 2009, Vincent O'Sullivan and Sam Neill accepted

1520-519: A response, Trenberth published further research on this topic in mid 2005.  Coincidentally, a record breaking hurricane season began shortly after (still in 2005) in which Hurricane Katrina caused all kinds of devastation in New Orleans . Two important studies who supported Kevin's research findings came out shortly thereafter: One by Kerry Emanuel , and another led by Peter Webster .  Further details on natural variability were provided in

1615-469: A result can lead to intense storms in some places and droughts in others. El Niño events cause short-term (approximately 1 year in length) spikes in global average surface temperature while La Niña events cause short term surface cooling. Therefore, the relative frequency of El Niño compared to La Niña events can affect global temperature trends on timescales of around ten years. The countries most affected by ENSO are developing countries that are bordering

1710-425: A secondary peak in sea surface temperature across the far eastern equatorial Pacific Ocean sometimes follows the initial peak. An especially strong Walker circulation causes La Niña, which is considered to be the cold oceanic and positive atmospheric phase of the broader El Niño–Southern Oscillation (ENSO) weather phenomenon, as well as the opposite of El Niño weather pattern, where sea surface temperature across

1805-570: Is 75 books or book chapters, 298 journal articles, 23 Technical Notes, 117 proceedings or preprints, and 87 other articles, plus four videos, for a total of 634 publications plus 4 videos, and many blogs and podcasts. On the Web of Science , there are 55,523 citations and an H index of 104 (104 publications have 104 or more citations). On Google Scholar, there are more than 132,000 citations and an H index of 136 (or 885 since 2018)." Furthermore, according to his staff page: "From 1996 until 2017 he ranked first in

1900-1010: Is a fellow of the American Meteorological Society (AMS), the American Association for Advancement of Science, and the American Geophysical Union; and an honorary fellow of the Royal Society of New Zealand . In 2000 he received the Jule G. Charney award from the American Meteorological Society ; in 2003 he was given the NCAR Distinguished Achievement Award; and in 2013 he was awarded the Prince Sultan Bin Abdulaziz International Prize for Water , and

1995-583: Is an oscillation in surface air pressure between the tropical eastern and the western Pacific Ocean waters. The strength of the Southern Oscillation is measured by the Southern Oscillation Index (SOI). The SOI is computed from fluctuations in the surface air pressure difference between Tahiti (in the Pacific) and Darwin, Australia (on the Indian Ocean). El Niño episodes have negative SOI, meaning there

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2090-458: Is because the total amount of water vapor is controlled by surface evaporation, not temperature. The prospects are therefore for more severe storms.   Until 2004, little attention had been paid to hurricanes and tropical storm changes, but the summer of 2004 was when four hurricanes made landfall in Florida . The question was whether there was a human global warming role in the activity and thus

2185-535: Is designed to recognise meritorious service, gallantry and bravery and long service". The monarch of New Zealand is the Sovereign of the order and the governor-general is its Chancellor. Appointments are made at five levels: From 2000 to 2009, the two highest levels of the Order were Principal Companion (PCNZM) and Distinguished Companion (DCNZM), without the appellation of "Sir" or "Dame". The number of Knights and Dames Grand Companion (and Principal Companions)

2280-405: Is known as Ekman transport . Colder water from deeper in the ocean rises along the continental margin to replace the near-surface water. This process cools the East Pacific because the thermocline is closer to the ocean surface, leaving relatively little separation between the deeper cold water and the ocean surface. Additionally, the northward-flowing Humboldt Current carries colder water from

2375-450: Is limited to 30 living people. Additionally, new appointments are limited to 15 Knights or Dames Companion, 40 Companions, 80 Officers and 140 Members per year. As well as the five levels, there are three different types of membership. Ordinary membership is limited to citizens of New Zealand or a Commonwealth realm . "Additional" members, appointed on special occasions, are not counted in the numerical limits. People who are not citizens of

2470-520: Is longer, it is classified as an El Niño "episode". It is thought that there have been at least 30 El Niño events between 1900 and 2024, with the 1982–83 , 1997–98 and 2014–16 events among the strongest on record. Since 2000, El Niño events have been observed in 2002–03, 2004–05, 2006–07, 2009–10, 2014–16 , 2018–19, and 2023–24 . Major ENSO events were recorded in the years 1790–93, 1828, 1876–78, 1891, 1925–26, 1972–73, 1982–83, 1997–98, 2014–16, and 2023–24. During strong El Niño episodes,

2565-553: Is lower pressure over Tahiti and higher pressure in Darwin. La Niña episodes on the other hand have positive SOI, meaning there is higher pressure in Tahiti and lower in Darwin. Low atmospheric pressure tends to occur over warm water and high pressure occurs over cold water, in part because of deep convection over the warm water. El Niño episodes are defined as sustained warming of the central and eastern tropical Pacific Ocean, thus resulting in

2660-406: Is typically around 0.5 m (1.5 ft) higher than near Peru because of the buildup of water in the West Pacific. The thermocline , or the transitional zone between the warmer waters near the ocean surface and the cooler waters of the deep ocean , is pushed downwards in the West Pacific due to this water accumulation. The total weight of a column of ocean water is almost the same in

2755-470: The Climatic Research Unit email controversy , an unlawfully disclosed email from Trenberth about one of his publications from 2009 was widely misrepresented; he had written, "The fact is that we can't account for the lack of warming at the moment and it is a travesty that we can't." In that 2009 paper, "An imperative for climate change planning: tracking Earth's global energy", Trenberth had discussed

2850-518: The International Date Line and 120°W ), including the area off the west coast of South America , as upwelling of cold water occurs less or not at all offshore. This warming causes a shift in the atmospheric circulation, leading to higher air pressure in the western Pacific and lower in the eastern Pacific, with rainfall reducing over Indonesia, India and northern Australia, while rainfall and tropical cyclone formation increases over

2945-646: The National Center for Atmospheric Research (NCAR) in 1984. His career at NCAR was in the Climate Analysis Section, where he was the Head for many years. He became a high level emeritus at NCAR as a Distinguished Scholar in 2019 and he moved back to New Zealand where he is also an honorary affiliated faculty at the University of Auckland . He has been prominent in most of the IPCC assessment reports and has also extensively served

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3040-548: The National Party caucus and public debate were split as to whether titles should be retained. There has long been debate in New Zealand regarding the appropriateness of titles. Some feel it is no longer appropriate as New Zealand has not been a colony since 1907, and to these people titles are out of step with present-day New Zealand. Others feel that titles carry both domestic and international recognition, and that awarded on

3135-677: The Order of the Bath , the Order of St Michael and St George , the Order of the British Empire , and the Order of the Companions of Honour , as well as the distinction of Knight Bachelor . The change came about after the Prime Minister's Honours Advisory Committee (1995) was created "to consider and present options and suggestions on the structure of a New Zealand Royal Honours System in New Zealand, which

3230-578: The Southern Ocean to the tropics in the East Pacific . The combination of the Humboldt Current and upwelling maintains an area of cooler ocean waters off the coast of Peru. The West Pacific lacks a cold ocean current and has less upwelling as the trade winds are usually weaker than in the East Pacific, allowing the West Pacific to reach warmer temperatures. These warmer waters provide energy for

3325-695: The WCRP Observation and Assimilation Panel from 2004 to 2010 and chaired the Global Energy and Water Exchanges (GEWEX) scientific steering group from 2010 to 2013 (member 2007 to 2014). In addition, he served on the Joint Scientific Committee of the WCRP and has made significant contributions to research into El Niño-Southern Oscillation . Trenberth began some fundamental work related to changes in extremes with climate change in 1998. Until then,

3420-629: The World Climate Research Programme (WCRP) in numerous ways. He has also served on many U.S. national committees. He served as editor of several journals. Trenberth played a key role in the Tropical Oceans Global Atmosphere program (TOGA) during 1989 to 1994 and he was co-chair of the Scientific Steering Group for the Climate Variability and Predictability ( CLIVAR ) program from 1996 to 1999. He chaired

3515-474: The upward movement of air . As a result, the warm West Pacific has on average more cloudiness and rainfall than the cool East Pacific. ENSO describes a quasi-periodic change of both oceanic and atmospheric conditions over the tropical Pacific Ocean. These changes affect weather patterns across much of the Earth. The tropical Pacific is said to be in one of three states of ENSO (also called "phases") depending on

3610-496: The 2017 Roger Revelle Medal from the American Geophysical Union for his work on climate change issues. In the 2024 New Year Honours , Trenberth was appointed a Companion of the New Zealand Order of Merit , for services to geophysics. Trenberth has New Zealand and U.S. citizenship. Trenberth was born in Christchurch on 8 November 1944, the eldest son of Ngaira Trenberth (née Eyre) and Edward Maurice Trenberth. He

3705-620: The Bjerknes feedback naturally triggers negative feedbacks that end and reverse the abnormal state of the tropical Pacific. This perspective implies that the processes that lead to El Niño and La Niña also eventually bring about their end, making ENSO a self-sustaining process. Other theories view the state of ENSO as being changed by irregular and external phenomena such as the Madden–Julian oscillation , tropical instability waves , and westerly wind bursts . The three phases of ENSO relate to

3800-692: The Climate Communication Prize from American Geophysical Union . Trenberth received the 2017 Roger Revelle Medal from the American Geophysical Union for his work on climate change issues. In January 2022 he was celebrated in a one-day Kevin Trenberth Symposium by the American Meteorological Society . In the 2024 New Year Honours , Trenberth was appointed a Companion of the New Zealand Order of Merit , for services to geophysics. According to his staff page at NCAR : "Kevin Trenberth's total number of publications (as of November 2023)

3895-420: The Climate Variability and Predictability ( CLIVAR ) program, and the Global Energy and Water Exchanges (GEWEX) project. Trenberth has published many publications (634 publications, four videos, and many blogs and podcasts as of November 2023). In addition, his work is also highly cited by other scientists which is shown by his h -index of 136 (136 papers have over 136 citations) in 2023. Trenberth received

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3990-474: The Coastal Niño Index (ICEN), strong El Niño Costero events include 1957, 1982–83, 1997–98 and 2015–16, and La Niña Costera ones include 1950, 1954–56, 1962, 1964, 1966, 1967–68, 1970–71, 1975–76 and 2013. Currently, each country has a different threshold for what constitutes an El Niño event, which is tailored to their specific interests, for example: In climate change science, ENSO is known as one of

4085-471: The Crown and nation or who have become distinguished by their eminence, talents, contributions or other merits", to recognise outstanding service to the Crown and people of New Zealand in a civil or military capacity. In the order of precedence , the New Zealand Order of Merit ranks immediately after the Order of New Zealand . Prior to 1996, New Zealanders received appointments to various British orders, such as

4180-603: The EP and CP types, and some scientists argue that ENSO exists as a continuum, often with hybrid types. The effects of the CP ENSO are different from those of the EP ENSO. The El Niño Modoki is associated with more hurricanes more frequently making landfall in the Atlantic. La Niña Modoki leads to a rainfall increase over northwestern Australia and northern Murray–Darling basin , rather than over

4275-492: The El Niño state. This process is known as Bjerknes feedback . Although these associated changes in the ocean and atmosphere often occur together, the state of the atmosphere may resemble a different ENSO phase than the state of the ocean or vice versa. Because their states are closely linked, the variations of ENSO may arise from changes in both the ocean and atmosphere and not necessarily from an initial change of exclusively one or

4370-491: The El Niños of 2006-07 and 2014-16 were also Central Pacific El Niños. Recent years when La Niña Modoki events occurred include 1973–1974, 1975–1976, 1983–1984, 1988–1989, 1998–1999, 2000–2001, 2008–2009, 2010–2011, and 2016–2017. The recent discovery of ENSO Modoki has some scientists believing it to be linked to global warming. However, comprehensive satellite data go back only to 1979. More research must be done to find

4465-541: The Equator, were defined. The western region is located over Indonesia and the eastern one over the equatorial Pacific, close to the South American coast. However, data on EQSOI goes back only to 1949. Sea surface height (SSH) changes up or down by several centimeters in Pacific equatorial region with the ESNO: El Niño causes a positive SSH anomaly (raised sea level) because of thermal expansion while La Niña causes

4560-592: The Order were recognised solely by the use of post-nominal letters. A National Business Review poll in February 2000 revealed that 54% of New Zealanders thought the titles should be scrapped. The Labour Government's April 2000 changes were criticised by opposition parties, with Richard Prebble of the ACT New Zealand party deriding the PCNZM's initials as standing for "a Politically Correct New Zealand that used to be

4655-520: The Pacific Ocean and are dependent on agriculture and fishing. In climate change science, ENSO is known as one of the internal climate variability phenomena. Future trends in ENSO due to climate change are uncertain, although climate change exacerbates the effects of droughts and floods. The IPCC Sixth Assessment Report summarized the scientific knowledge in 2021 for the future of ENSO as follows: "In

4750-453: The Walker circulation, which was named after Gilbert Walker who discovered the Southern Oscillation during the early twentieth century. The Walker circulation is an east-west overturning circulation in the vicinity of the equator in the Pacific. Upward air is associated with high sea temperatures, convection and rainfall, while the downward branch occurs over cooler sea surface temperatures in

4845-454: The West Pacific northeast of Australia averages around 28–30 °C (82–86 °F). SSTs in the East Pacific off the western coast of South America are closer to 20 °C (68 °F). Strong trade winds near the equator push water away from the East Pacific and towards the West Pacific. This water is slowly warmed by the Sun as it moves west along the equator. The ocean surface near Indonesia

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4940-460: The West Pacific to a depth of about 30 m (90 ft) in the East Pacific. Cooler deep ocean water takes the place of the outgoing surface waters in the East Pacific, rising to the ocean surface in a process called upwelling . Along the western coast of South America, water near the ocean surface is pushed westward due to the combination of the trade winds and the Coriolis effect . This process

5035-429: The asymmetric nature of the warm and cold phases of ENSO, some studies could not identify similar variations for La Niña, both in observations and in the climate models, but some sources could identify variations on La Niña with cooler waters on central Pacific and average or warmer water temperatures on both eastern and western Pacific, also showing eastern Pacific Ocean currents going to the opposite direction compared to

5130-436: The atmospheric and oceanic conditions. When the tropical Pacific roughly reflects the average conditions, the state of ENSO is said to be in the neutral phase. However, the tropical Pacific experiences occasional shifts away from these average conditions. If trade winds are weaker than average, the effect of upwelling in the East Pacific and the flow of warmer ocean surface waters towards the West Pacific lessen. This results in

5225-434: The basis of merit they remain an appropriate recognition of excellence. In April 2000 the then new Labour Prime Minister, Helen Clark , announced that knighthoods and damehoods had been abolished and the order's statutes amended. From 2000 to 2009, the two highest levels of the Order were Principal Companion (PCNZM) and Distinguished Companion (DCNZM), without the appellation of "Sir" or "Dame"; appointment to all levels of

5320-578: The change in December 2021 and June 2022, respectively. A change to non-titular honours was a recommendation contained within the original report of the 1995 honours committee ( The New Zealand Royal Honours System: The Report of the Prime Minister’s Honours Advisory Committee ) which prompted the creation of the New Zealand Order of Merit. Titular honours were incorporated into the new system before its implementation in 1996 after

5415-591: The correlation and study past El Niño episodes. More generally, there is no scientific consensus on how/if climate change might affect ENSO. There is also a scientific debate on the very existence of this "new" ENSO. A number of studies dispute the reality of this statistical distinction or its increasing occurrence, or both, either arguing the reliable record is too short to detect such a distinction, finding no distinction or trend using other statistical approaches, or that other types should be distinguished, such as standard and extreme ENSO. Likewise, following

5510-543: The currents in traditional La Niñas. Coined by the Peruvian Comité Multisectorial Encargado del Estudio Nacional del Fenómeno El Niño (ENFEN), ENSO Costero, or ENSO Oriental, is the name given to the phenomenon where the sea-surface temperature anomalies are mostly focused on the South American coastline, especially from Peru and Ecuador. Studies point many factors that can lead to its occurrence, sometimes accompanying, or being accompanied, by

5605-511: The damage. To Trenberth it was obvious that there was, and he spoke up when official NOAA statements on hurricanes attributed it all to natural climate variability . Trenberth participated in a tele-news conference, set up by Harvard University , and cautiously suggested that global warming was undoubtedly playing some role. This led to a major outcry from some hurricane meteorologists, and extensive criticism for example by Christopher Landsea , an American meteorologist .  As

5700-445: The distribution of heat and how it was affected by climate forcing , including greenhouse gas changes. This could be tracked from 1993 to 2003, but for the period from 2004 to 2008 it was not then possible to explain the relatively cool temperatures of 2008. Trenberth has stated later: "It is amazing to see this particular quote lambasted so often. It stems from a paper I published this year bemoaning our inability to effectively monitor

5795-461: The east. During El Niño, as the sea surface temperatures change so does the Walker Circulation. Warming in the eastern tropical Pacific weakens or reverses the downward branch, while cooler conditions in the west lead to less rain and downward air, so the Walker Circulation first weakens and may reverse.   The Southern Oscillation is the atmospheric component of ENSO. This component

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5890-614: The eastern Pacific below average, and air pressure high in the eastern Pacific and low in the western Pacific. The ENSO cycle, including both El Niño and La Niña, causes global changes in temperature and rainfall. If the temperature variation from climatology is within 0.5 °C (0.9 °F), ENSO conditions are described as neutral. Neutral conditions are the transition between warm and cold phases of ENSO. Sea surface temperatures (by definition), tropical precipitation, and wind patterns are near average conditions during this phase. Close to half of all years are within neutral periods. During

5985-479: The eastern Pacific. However, in the 1990s and 2000s, variations of ENSO conditions were observed, in which the usual place of the temperature anomaly (Niño 1 and 2) is not affected, but an anomaly also arises in the central Pacific (Niño 3.4). The phenomenon is called Central Pacific (CP) ENSO, "dateline" ENSO (because the anomaly arises near the dateline ), or ENSO "Modoki" (Modoki is Japanese for "similar, but different"). There are variations of ENSO additional to

6080-404: The eastern equatorial part of the central Pacific Ocean will be lower than normal by 3–5 °C (5.4–9 °F). The phenomenon occurs as strong winds blow warm water at the ocean's surface away from South America, across the Pacific Ocean towards Indonesia. As this warm water moves west, cold water from the deep sea rises to the surface near South America. The movement of so much heat across

6175-567: The eastern portion of the country as in a conventional EP La Niña. Also, La Niña Modoki increases the frequency of cyclonic storms over Bay of Bengal , but decreases the occurrence of severe storms in the Indian Ocean overall. The first recorded El Niño that originated in the central Pacific and moved toward the east was in 1986. Recent Central Pacific El Niños happened in 1986–87, 1991–92, 1994–95, 2002–03, 2004–05 and 2009–10. Furthermore, there were "Modoki" events in 1957–59, 1963–64, 1965–66, 1968–70, 1977–78 and 1979–80. Some sources say that

6270-453: The energy flows associated with short-term climate variability. It is quite clear from the paper that I was not questioning the link between anthropogenic greenhouse gas emissions and warming , or even suggesting that recent temperatures are unusual in the context of short-term natural variability." For decades, Kevin Trenberth has been outspoken about climate change and the urgency to take action. One of his key messages has been: "It’s real,

6365-496: The focus of the scientific community had been mainly on changes in average temperatures and precipitation . Trenberth pointed out that the intermittent nature of precipitation mandated attention to intensity, frequency, duration, and type as well as amount. All storms reach out and gather in the available water vapor, which fuels the storm. Therefore, increases in water vapor in the atmosphere with higher temperatures will lead to greater intensity but less frequency of storms. This

6460-718: The following years: Transitional phases at the onset or departure of El Niño or La Niña can also be important factors on global weather by affecting teleconnections . Significant episodes, known as Trans-Niño, are measured by the Trans-Niño index (TNI). Examples of affected short-time climate in North America include precipitation in the Northwest US and intense tornado activity in the contiguous US. The first ENSO pattern to be recognised, called Eastern Pacific (EP) ENSO, to distinguish if from others, involves temperature anomalies in

6555-409: The globe. Atlantic and Pacific hurricanes can have different characteristics due to lower or higher wind shear and cooler or warmer sea surface temperatures. La Niña events have been observed for hundreds of years, and occurred on a regular basis during the early parts of both the 17th and 19th centuries. Since the start of the 20th century, La Niña events have occurred during

6650-471: The internal climate variability phenomena. The other two main ones are Pacific decadal oscillation and Atlantic multidecadal oscillation . La Niña impacts the global climate and disrupts normal weather patterns, which can lead to intense storms in some places and droughts in others. El Niño events cause short-term (approximately 1 year in length) spikes in global average surface temperature while La Niña events cause short term cooling. Therefore,

6745-427: The last several decades, the number of El Niño events increased, and the number of La Niña events decreased, although observation of ENSO for much longer is needed to detect robust changes. Studies of historical data show the recent El Niño variation is most likely linked to global warming. For example, some results, even after subtracting the positive influence of decadal variation, are shown to be possibly present in

6840-528: The long term, it is very likely that the precipitation variance related to El Niño–Southern Oscillation will increase". The scientific consensus is also that "it is very likely that rainfall variability related to changes in the strength and spatial extent of ENSO teleconnections will lead to significant changes at regional scale". The El Niño–Southern Oscillation is a single climate phenomenon that periodically fluctuates between three phases: Neutral, La Niña or El Niño. La Niña and El Niño are opposite phases in

6935-629: The neutral ENSO phase, other climate anomalies/patterns such as the sign of the North Atlantic Oscillation or the Pacific–North American teleconnection pattern exert more influence. El Niño conditions are established when the Walker circulation weakens or reverses and the Hadley circulation strengthens, leading to the development of a band of warm ocean water in the central and east-central equatorial Pacific (approximately between

7030-674: The number of highly cited papers published out of all 223,246 published environmental scientists." He has also written numerous articles for the general public, for example in The Conversation and New Zealand's Newsroom. Companion of the New Zealand Order of Merit The New Zealand Order of Merit is an order of merit in the New Zealand royal honours system . It was established by royal warrant on 30 May 1996 by Elizabeth II , Queen of New Zealand , "for those persons who in any field of endeavour, have rendered meritorious service to

7125-400: The observed phenomenon of more frequent and stronger El Niño events occurs only in the initial phase of the global warming, and then (e.g., after the lower layers of the ocean get warmer, as well), El Niño will become weaker. It may also be that the stabilizing and destabilizing forces influencing the phenomenon will eventually compensate for each other. The consequences of ENSO in terms of

7220-560: The option to convert their awards into Knighthoods or Damehoods. The restoration was welcomed by Monarchy New Zealand . The option has been taken up by 72 of those affected, including rugby great Colin Meads . Former Labour MP Margaret Shields was one of those who accepted a Damehood, despite receiving a letter from former Prime Minister Helen Clark "setting out why Labour had abolished the titles and saying she hoped she would not accept one". Clark's senior deputy, Michael Cullen , also accepted

7315-636: The oscillation which are deemed to occur when specific ocean and atmospheric conditions are reached or exceeded. An early recorded mention of the term "El Niño" ("The Boy" in Spanish) to refer to climate occurred in 1892, when Captain Camilo Carrillo told the geographical society congress in Lima that Peruvian sailors named the warm south-flowing current "El Niño" because it was most noticeable around Christmas. Although pre-Columbian societies were certainly aware of

7410-415: The other. Conceptual models explaining how ENSO operates generally accept the Bjerknes feedback hypothesis. However, ENSO would perpetually remain in one phase if Bjerknes feedback were the only process occurring. Several theories have been proposed to explain how ENSO can change from one state to the next, despite the positive feedback. These explanations broadly fall under two categories. In one view,

7505-417: The peruvian coast, and increased rainfall and decreased temperatures on its mountainous and jungle regions. Because they don't influence the global climate as much as the other types, these events present lesser and weaker correlations to other significant ENSO features, neither always being triggered by Kelvin waves , nor always being accompanied by proportional Southern Oscillation responses. According to

7600-483: The phenomenon, the indigenous names for it have been lost to history. The capitalized term El Niño refers to the Christ Child , Jesus , because periodic warming in the Pacific near South America is usually noticed around Christmas . Originally, the term El Niño applied to an annual weak warm ocean current that ran southwards along the coast of Peru and Ecuador at about Christmas time. However, over time

7695-500: The problem is cumulative, and we’re causing it. Today’s blanket of greenhouse gases would disperse only over centuries. Cutting emissions is the most important of all possible responses." And "we also have to build resilience to the new  extremes ". Trenberth was appointed Distinguished Scholar at NCAR in 2020. He is also an honorary faculty member in the Physics Department at the University of Auckland , New Zealand. Trenberth

7790-406: The relative frequency of El Niño compared to La Niña events can affect global temperature trends on decadal timescales. There is no sign that there are actual changes in the ENSO physical phenomenon due to climate change. Climate models do not simulate ENSO well enough to make reliable predictions. Future trends in ENSO are uncertain as different models make different predictions. It may be that

7885-418: The rest of the tropics and subtropics. The two phenomena last a year or so each and typically occur every two to seven years with varying intensity, with neutral periods of lower intensity interspersed. El Niño events can be more intense but La Niña events may repeat and last longer. A key mechanism of ENSO is the Bjerknes feedback (named after Jacob Bjerknes in 1969) in which the atmospheric changes alter

7980-424: The sea temperatures that in turn alter the atmospheric winds in a positive feedback. Weaker easterly trade winds result in a surge of warm surface waters to the east and reduced ocean upwelling on the equator . In turn, this leads to warmer sea surface temperatures (called El Niño), a weaker Walker circulation (an east-west overturning circulation in the atmosphere) and even weaker trade winds. Ultimately

8075-431: The strength of the trade winds was first identified by Jacob Bjerknes in 1969. Bjerknes also hypothesized that ENSO was a positive feedback system where the associated changes in one component of the climate system (the ocean or atmosphere) tend to reinforce changes in the other. For example, during El Niño, the reduced contrast in ocean temperatures across the Pacific results in weaker trade winds, further reinforcing

8170-451: The style Sir for males and Dame for females. The order's statutes grant heraldic privileges to members of the first and second level, who are entitled to have the Order's circlet ("a green circle, edged gold, and inscribed with the Motto of the Order in gold") surrounding their shield. Grand Companions are also entitled to heraldic supporters . The Chancellor is entitled to supporters and

8265-521: The temperature anomalies and precipitation and weather extremes around the world are clearly increasing and associated with climate change . For example, recent scholarship (since about 2019) has found that climate change is increasing the frequency of extreme El Niño events. Previously there was no consensus on whether climate change will have any influence on the strength or duration of El Niño events, as research alternately supported El Niño events becoming stronger and weaker, longer and shorter. Over

8360-618: The term has evolved and now refers to the warm and negative phase of the El Niño–Southern Oscillation (ENSO). The original phrase, El Niño de Navidad , arose centuries ago, when Peruvian fishermen named the weather phenomenon after the newborn Christ. La Niña ("The Girl" in Spanish) is the colder counterpart of El Niño, as part of the broader ENSO climate pattern . In the past, it was also called an anti-El Niño and El Viejo, meaning "the old man." A negative phase exists when atmospheric pressure over Indonesia and

8455-452: The tropical Pacific Ocean. The low-level surface trade winds , which normally blow from east to west along the equator, either weaken or start blowing from the other direction. El Niño phases are known to happen at irregular intervals of two to seven years, and lasts nine months to two years. The average period length is five years. When this warming occurs for seven to nine months, it is classified as El Niño "conditions"; when its duration

8550-442: The warm waters in the western tropical Pacific are depleted enough so that conditions return to normal. The exact mechanisms that cause the oscillation are unclear and are being studied. Each country that monitors the ENSO has a different threshold for what constitutes an El Niño or La Niña event, which is tailored to their specific interests. El Niño and La Niña affect the global climate and disrupt normal weather patterns, which as

8645-466: The west Pacific is abnormally high and pressure over the east Pacific is abnormally low, during El Niño episodes, and a positive phase is when the opposite occurs during La Niña episodes, and pressure over Indonesia is low and over the west Pacific is high. On average, the temperature of the ocean surface in the tropical East Pacific is roughly 8–10 °C (14–18 °F) cooler than in the tropical West Pacific . The sea surface temperature (SST) of

8740-441: The western and east Pacific. Because the warmer waters of the upper ocean are slightly less dense than the cooler deep ocean, the thicker layer of warmer water in the western Pacific means the thermocline there must be deeper. The difference in weight must be enough to drive any deep water return flow. Consequently, the thermocline is tilted across the tropical Pacific, rising from an average depth of about 140 m (450 ft) in

8835-411: Was a trigger for the changes in the Pacific, and I think that's very probably the beginning of the hiatus". He said that, eventually, "it will switch back in the other direction." Trenberth's explanation attracted wide attention in the press. Kevin Trenberth was "one of the victims in “Climategate” where hacked emails from climate scientists were distorted by climate-change deniers to sow confusion." In

8930-584: Was educated at Linwood High School , where he was dux in 1962, and went on to study at the University of Canterbury , graduating BSc (Hons) with first-class honours in 1966. After completing his studies at Canterbury, Trenberth worked at the Meteorological Service of New Zealand for two years, and was awarded a research fellowship in 1968 that allowed him to undertake doctoral studies at Massachusetts Institute of Technology . His ScD thesis, supervised by Edward Norton Lorenz and completed in 1972,

9025-721: Was titled Dynamic coupling of the stratosphere with the troposphere and sudden stratospheric warmings . Trenberth returned to the Meteorological Service in Wellington , New Zealand, in 1972 after completing his PhD in the US. He worked there as a research scientist in the New Zealand Meteorological Service (1966–77). In 1977 he moved to the University of Illinois in 1977 where he became a full professor and worked there for nearly seven years. After that, he joined

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