EF8C. Stay Current—What is El Niño?

2024-10-10. El Niño fingered as likely culprit in record 2023 temperatures. By Paul Voosen, Science. Excerpt: For the past year, alarm bells have been going off in climate science: Last year’s average global temperature was so high, shooting up nearly 0.3°C above the previous year to set a new record, that human-driven global warming and natural short-term climate swings seemingly couldn’t explain it. …Now, a new series of studies suggests most of the 2023 jump can be explained instead by a familiar climate driver: the shifting waters of the tropical Pacific Ocean. The combination of a 3-year-long La Niña, which suppressed global temperatures from 2020 to 2022, followed by a strong El Niño could account for the unexpected temperature jump, the work suggests…. Full article at https://www.science.org/content/article/el-ni%C3%B1o-fingered-likely-culprit-record-2023-temperatures.

2024-02-01. The Coral Chronicles. [https://www.science.org/content/article/remote-pacific-island-clues-el-ninos-future-preserved-ancient-reefs] By PAUL VOOSEN, Science. Excerpt: …The El Niño event, now at its peak, is driving weather extremes not just in Vanuatu, but all over the planet. Drought has struck Australia, as well as the Amazon, where intolerably hot waters have suffocated endangered pink dolphins. Rains have drenched Peru, spreading dengue, while warm waters intruding near its coast have disrupted the world’s largest anchovy fishery and forced the nation to cancel a lucrative fishing season. Those same warm waters accelerated Hurricane Otis, which devastated Acapulco and Mexico’s Pacific coast in October 2023. The effects have been truly global: By suppressing the Pacific’s ability to absorb heat from the atmosphere, El Niño helped make 2023 the hottest year in history by a huge margin. …TWENTY THOUSAND YEARS AGO, at the peak of the last ice age, Earth was 6°C cooler than today. Glaciers buried the northern continents. But in the tropical Pacific, things wouldn’t have looked so different, with one exception: Every island would have been much, much taller. With the planet’s water locked up in ice sheets, sea levels were 120 meters lower. …Corals continued to grow around these towering islands, capturing the swings of El Niño and La Niña events as chemical signals within their skeletons much like tree rings. Later, when the ice sheets melted, the reefs at Vanuatu and elsewhere were submerged, putting their ancient records of El Niño and La Niña out of reach. …Ancient corals can capture the climatic effects of El Niño and La Niña events that occurred thousands of years ago. But most reefs from the last ice age are submerged by more than 100 meters of water. On the island of Espiritu Santo in Vanuatu, however, tectonic forces have lifted ancient corals back to the surface….

2023-09-20. Hurricane Nigel, a Category 2 Storm, Is Expected to Weaken. [https://www.nytimes.com/article/tropical-storm-nigel-hurricane.html] By Judson Jones, The New York Times. Excerpt: …The Atlantic hurricane season started on June 1 and runs through Nov. 30. In late May, the National Oceanic and Atmospheric Administration predicted that there would be 12 to 17 named storms this year, a “near-normal” amount. On Aug. 10, NOAA officials revised their estimate upward, to 14 to 21 storms. …A record 30 named storms took place in 2020. This year features an El Niño pattern, which arrived in June. …it typically impedes the number of Atlantic hurricanes …increases the amount of wind shear, …. Hurricanes need a calm environment to form, and the instability caused by increased wind shear makes those conditions less likely. (El Niño has the opposite effect in the Pacific, reducing the amount of wind shear.) At the same time, this year’s heightened sea surface temperatures pose a number of threats, including the ability to supercharge storms. …There is solid consensus among scientists that hurricanes are becoming more powerful because of climate change. …Climate change is also affecting the amount of rain that storms can produce. In a warming world, the air can hold more moisture, which means a named storm can hold and produce more rainfall, like Hurricane Harvey did in Texas in 2017, when some areas received more than 40 inches of rain in less than 48 hours. …storms have slowed down, sitting over areas for longer, over the past few decades. …the amount of moisture the storm can absorb increases. …the amount of rain that falls over a single location increases; in 2019, for example, Hurricane Dorian slowed to a crawl over the northwestern Bahamas, resulting in a total rainfall of 22.84 inches in Hope Town during the storm…. For GSS Energy Flow chapter 8.

2023-04-28. Ocean El Niño monitor gets an upgrade. [https://www.science.org/content/article/ocean-el-nino-monitor-gets-upgrade] By Paul Voosen, Science. Excerpt: For 3 years in a row, cool La Niña conditions have reigned in the tropical Pacific Ocean, suppressing the steady march of global warming. But warm waters are now rolling east and gathering off the west coast of South America, signaling the likely arrival of El Niño later this year and, next year, a surge in heat that could push the planet past 1.5°C of warming. These fluctuations in the Pacific—the greatest short-term control on global climate—once caught the world off guard. But they are now predictable months in advance, largely because of the Tropical Atmosphere Ocean (TAO) array, a series of 55 U.S. buoys, moored to the sea floor, that stretch some 13,000 kilometers along the equator. Now, the TAO array is getting a $23 million overhaul, the first since it was set up in the mid-1990s, the National Oceanic and Atmospheric Administration (NOAA) says. The revamped buoys, the first of which was deployed on 13 April, will be more robust and able to monitor the ocean below in more detail, potentially allowing earlier and more accurate El Niño forecasts. Some will be moved into locations north of the equator, to enable better forecasts of cyclones and atmospheric rivers, the parades of storms that can inundate coastal regions such as California….

2023-03-24. Supercharged El Niño Could Speed Up Southern Ocean Warming. [https://eos.org/articles/supercharged-el-nino-could-speed-up-southern-ocean-warming] By Erin Martin-Jones, Eos/AGU. Excerpt: When easterly winds weaken over the tropical Pacific Ocean, a string of weather extremes unfolds all over the globe, with impacts ranging from flooding in South American deserts to reduced monsoon rains in Indonesia and India. This shift in wind and water currents, known as the El Niño–Southern Oscillation (ENSO), will become more intense if global temperatures continue to rise. Research now has revealed that projected changes to this global weather maker will also influence the remote Southern Ocean. Using the latest climate models, scientists have shown that enhanced El Niño events will likely speed the heating of deep-ocean waters around Antarctica, with the potential for accelerated melting of the continent’s land-held ice. Scientists are concerned about how stronger El Niño events could affect the Antarctic because of the potential for sea level rise. The Antarctic Ice Sheet holds about 60% of the world’s freshwater—enough to raise global sea levels by around 70 meters. …In a study published in Nature Climate Change, Cai and his colleagues used climate models to make the first assessments of how ENSO intensification could affect Antarctic climate….

2023-02-16. Scientists Wondered if Warming Caused Argentina’s Drought. The Answer: No. [https://www.nytimes.com/2023/02/16/climate/argentina-drought.html] By Henry Fountain, The New York Times. Excerpt: Lack of rainfall that caused severe drought in Argentina and Uruguay last year was not made more likely by climate change, scientists said Thursday. But global warming was a factor in extreme heat experienced in both countries that made the drought worse, they said. The researchers, part of a loose-knit group called World Weather Attribution that studies recent extreme weather for signs of the influence of climate change, said that the rainfall shortage was a result of natural climate variability. Specifically, they said, the presence of La Niña, a climate pattern linked to below-normal sea-surface temperatures in the Pacific that influences weather around the world, most likely affected precipitation. La Niña usually occurs once every three to five years, often alternating with El Niño, which is linked to above-normal sea temperatures. But La Niña conditions have persisted for most of the past three years, and central South America has been drier than normal for most of that time….

2021-11-12. The Benefits of Better Ocean Weather Forecasting. By Charlotte DeMott,  Ángel G. Muñoz,  Christopher D. Roberts,  Claire M. Spillman and  F. Vitart, AGU, Eos. Excerpt: Like atmospheric variability, variability in ocean conditions, such as sea surface temperature and salinity and sea ice cover and thickness, can have major effects on human activities and ecosystems both at sea and on land. For example, this variability, also called “ocean weather,” can influence the occurrence of fair-weather coastal flooding, which disrupts transportation and degrades coastal infrastructure around the world. Meanwhile, sea ice movement in an increasingly ice-free Arctic Ocean poses risks to high-latitude shipping. Elsewhere, changes in ocean upwelling can enhance coastal commercial fishing activity, whereas marine heat waves can disrupt fisheries and coral communities. As with atmospheric weather forecasts, knowing about ocean weather in advance can help minimize disruptions to everyday public and commercial activity, keep coastal and maritime workers safe, and aid marine conservation efforts. Unlike atmospheric weather, however, which evolves on daily timescales, ocean weather typically evolves on weekly to monthly timescales…. Slowly varying ocean conditions can regulate atmospheric weather, so including ocean feedbacks in atmospheric forecasting models can extend these models’ predictive skill by several days.… [https://eos.org/features/the-benefits-of-better-ocean-weather-forecasting]

2021-05-20. [https://eos.org/articles/your-summer-outlook-cloudy-with-an-above-normal-chance-of-hurricanes] – Your Summer Outlook: Cloudy with an Above-Normal Chance of Hurricanes. Source: By Jenessa Duncombe, Eos/AGU. Excerpt: This year may be the sixth consecutive above-normal Atlantic hurricane season. NOAA released its season outlook today and predicted that it will be another doozy in the Atlantic. …“Climate change has not been directly linked to the frequency of named tropical storms, but it has been linked to an increase in the intensity of storms,” said Rosencrans. The reason for the higher number of storms this year comes from the ongoing periodic climate fluctuation called the Atlantic Multidecadal Oscillation. We have been in a warm phase since 1995, leading to more storms. …The storm season could be on the more extreme end of the outlook if another large climate phenomenon, the El Niño–Southern Oscillation (ENSO), switches to its La Niña phase. …Last year was a record-setting year for hurricanes. We had 30 named storms, surpassing the previous record of 28 in 2005…. 

2020-10-16. Distant seas might predict Colorado River droughts. By Warren Cornwall, Science Magazine. Excerpt: …scientists say they may have come up with a potential early warning system for the Colorado’s water levels—by watching temperature patterns in the Atlantic and Pacific oceans, thousands of kilometers away. …Scientists have long recognized links between ocean temperatures and continental weather patterns. Most famously, the central Pacific’s El Niño—a periodic warming of ocean waters—has been tied to drought in Africa, torrential rains on the Pacific coast of North America, and wildfires in South America. …The scientists found that in the seven most extreme drought years over the past 6 decades, including 2012, the downturn nearly always happened on the heels of a multiyear pattern of global ocean temperatures, they report this month in Communications Earth & Environment. Those patterns started with unusual warm spells in the tropical Atlantic 3 to 4 years before the drought, and continued with warming in the northern Pacific and cooling in the central Pacific 1 to 2 years before the drought…. [https://www.sciencemag.org/news/2020/10/distant-seas-might-predict-colorado-river-droughts] 
2020-09-10. September 2020 ENSO update: La Niña is here! By: Emily Becker, NOAA. Excerpt: La Niña conditions were present in August, and there’s a 75% chance they’ll hang around through the winter. NOAA has issued a La Niña Advisory. …La Niña’s altered atmospheric circulation over the Pacific Ocean affects global weather and climate. …La Niña can make certain outcomes more likely. This includes more rain than average through Indonesia, cooler and wetter weather in southern Africa, and drier weather in southeastern China, among other impacts. …One important global impact of La Niña is its effect on the Atlantic hurricane season. La Niña reduces wind shear—the change in winds between the surface and the upper levels of the atmosphere—allowing hurricanes to grow. The likelihood of La Niña was factored into NOAA’s August outlook for the Atlantic hurricane season, which favored an “extremely active” season. As of September 8th, we have seen 17 named storms so far this season, and the forecast is for a total of 19-25 named storms (the hurricane season ends on Nov. 30th)…. [https://www.climate.gov/news-features/blogs/enso/september-2020-enso-update-la-niña-here]  

2019-12-31. A warning from ancient tree rings: The Americas are prone to catastrophic, simultaneous droughts. By Paul Voosen, Science Magazine.  [https://www.sciencemag.org/news/2019/12/warning-ancient-tree-rings-americas-are-prone-catastrophic-simultaneous-droughts] Excerpt: For 10 years, central Chile has been gripped by unrelenting drought. With 30% less rainfall than normal, verdant landscapes have withered, reservoirs are low, and more than 100,000 farm animals have died. The dry spell has lasted so long that researchers are calling it a “megadrought,” rivaling dry stretches centuries ago. It’s not so different from the decadelong drought that California, some 8000 kilometers away, endured until this year. By analyzing tree ring records, scientists have now found evidence that such tandem droughts are more than a coincidence: They are surprisingly common over the past 1200 years, and they may often share a common cause—an abnormally cool state of the eastern Pacific Ocean known as La Niña. …Nor is it clear how the drought patterns will change as climate warms. A warming atmosphere alone seems certain to make megadroughts more frequent, especially in the Southwest. But scientists remain divided on how climate change will affect the El Niño-La Niña cycle. Models suggest El Niño will dominate, but in the past few decades, La Niña has seemed to be more frequent. …As bad as the drought in Chile is today, it barely qualifies as a megadrought when compared with the medieval ones, which were longer and more severe. Clearly, there was something about that period that switched off in recent centuries, Cook says. If that pattern somehow came back, with greenhouse warming amplifying it, Cook says, “then things could get quite catastrophic.”….

2019-04-02. North Atlantic Circulation Patterns Reveal Seas of Change. By Mary Caperton Morton, Eos/AGU. Excerpt: Atlantic Meridional Overturning Circulation (AMOC), involving the deep-ocean mixing of warm, salty waters with colder, fresher waters in the North Atlantic, is a major influencer of Earth’s climate. As warm tropical currents journey north, pushed by prevailing winds, they cool, become denser, and sink in a process known as overturning. Historically, most models have shown that the bulk of this overturning occurs in the Labrador Sea, west of Greenland. But a new study indicates that the eastern North Atlantic between Greenland and Scotland may actually be the dominant overturning venue. … As the overturning of seawater in the North Atlantic changes, so does the ocean’s ability to absorb and store atmospheric carbon, Lozier says. “Since the Industrial Revolution, the oceans have taken up about a third of the anthropogenic carbon dioxide humans have produced.” Half of that carbon dioxide is now sequestered in the deep ocean, including the North Atlantic. “If the overturning slows down, the ocean will take up less anthropogenic carbon, which would leave more anthropogenic carbon in the atmosphere, which could trigger rapid warming.”…  

2018-03-08. Fleet of sailboat drones could monitor climate change’s effect on oceans. By Paul Voosen, Science. Excerpt: Two 7-meter-long sailboats are set to return next month to California, after nearly 8 months tacking across the Pacific Ocean. …No captains will be at their helms. That is not because of a mutiny. These sailboats, outfitted with sensors to probe the ocean, are semiautonomous drones, developed by Saildrone, a marine tech startup based in Alameda, California, in close collaboration with the National Oceanic and Atmospheric Administration (NOAA) in Washington, D.C. The voyage is the longest test for the drones and also the first science test in the Pacific—an important step in showing that they could replace an aging and expensive array of buoys that are the main way scientists sniff out signs of climate-disrupting El Niño events…. http://www.sciencemag.org/news/2018/03/fleet-sailboat-drones-could-monitor-climate-change-s-effect-oceans

2016-12-27. Notorious Ocean Current Is Far Stronger Than Previously Thought. By Emily Underwood, EoS Earth & Space news, AGU. Excerpt: Notorious among sailors for its strength and the rough seas it creates, the Antarctic Circumpolar Current (ACC) is the largest wind-driven current on Earth and the only ocean current to travel all the way around the planet. Now, researchers have found that the current transports 30% more water than previously thought. The revised estimate is an important update for scientists studying how the world’s oceans will respond to a warming climate. The ACC transports massive amounts of water between the Atlantic, Indian, and Pacific oceans in an eastward loop. …For the new study, Donohue et al. installed gauges along the bottom of Drake Passage, spanning an 800-kilometer passage between Cape Horn and the South Shetland Islands of Antarctica. …The classic estimate used for the ACC’s transport is 134 sverdrups (Sv). One sverdrup is equivalent to 1 million cubic meters per second. Using 4 years of data collection from 2007 to 2011, the researchers found that the transport rate was 30% higher than historical estimates, around 173.3 Sv. Although it’s possible that stronger winds in the Southern Ocean over the past few decades may have caused the increase, satellite-based studies showing that transport has remained fairly steady during this time suggest that improved measurement tools, not increased wind, are responsible for the discrepancy. (Geophysical Research Letters, doi:10.1002/2016GL070319, 2016)…  https://eos.org/research-spotlights/notorious-ocean-current-is-far-stronger-than-previously-thought

2016-02-01. Studying the Heart of El Niño, Where Its Weather Begins. By Henry Fountain, The New York Times. Excerpt: …In a Gulfstream jet more accustomed to hunting hurricanes in the Atlantic, researchers with the National Oceanic and Atmospheric Administration were cruising this desolate stretch of tropical ocean where the northern and southern trade winds meet. …“One of the most important questions is to resolve how well our current weather and climate models do in representing the tropical atmosphere’s response to an El Niño,” said Randall Dole, a senior scientist at NOAA’s Earth System Research Laboratory and one of the lead researchers on the project.  …An El Niño forms about every two to seven years, when the surface winds that typically blow from east to west slacken. As a result, warm water that normally pools along the Equator in the western Pacific piles up toward the east instead. Because of this shift, the expanse of water — which in this El Niño has made the central and eastern Pacific as much as 5 degrees Fahrenheit hotter than usual — acts as a heat engine, affecting the jet streams that blow at high altitudes. That, in turn, can bring more winter rain to the lower third of the United States and dry conditions to southern Africa, among El Niño’s many possible effects….  http://www.nytimes.com/2016/02/02/science/where-el-nino-weather-begins-pacific-ocean-noaa.html

2015-12-15. NASA Examines Global Impacts of the 2015 El Niño. By NASA Release 15-235. Excerpt: People the world over are feeling, or soon will feel, the effects of the strongest El Niño event since 1997-98, currently unfolding in the eastern equatorial Pacific Ocean. New satellite observations are beginning to show scientists its impact on the distribution of rain, tropospheric ozone and wildfires around the globe. …this year’s strong El Niño likely will bring more precipitation to California and some relief for the drought. Due to this El Niño, tropospheric ozone, a pollutant and greenhouse gas, is seen decreasing over mid-latitude locations such as the United States, and the risk of fires across the tropics is showing signs of increasing. …El Niño’s elevated sea surface temperatures shift rain patterns by affecting the temperature of the air above the ocean, which alters how winds and air masses circulate air around the planet. The change in winds also affects the distribution of tropospheric ozone around the planet. Tropospheric ozone exists in the atmospheric layer closest to the surface and comprises ozone produced naturally and from human pollution. Ozone in the troposphere is a greenhouse gas and a health hazard.  …During El Niños, the number and size of fires increases in tropical forests across Asia and South America. …Fires in tropical forests also accelerate carbon dioxide buildup in the atmosphere and reduce air quality….  http://www.nasa.gov/press-release/nasa-examines-global-impacts-of-the-2015-el-ni-o

2015-06-17. Mysterious Warm Blob in Pacific Wreaking Havoc. By Patrick J. Kiger, D news. Excerpt:  A large expanse of unusually warm water in the northern Pacific Ocean continues to grow and is having a profound effect upon marine animals from Mexico to Alaska, and may be altering weather across the continent. “The blob,” a term coined by University of Washington meteorologist Nicholas Bond, who was among those who first observed it in late 2013, consists of  water that is roughly around 5 degrees Fahrenheit warmer than the typical ocean temperature. While that may not seem like much of a difference, the circular patch of warmth, which started as a small patch of water off the coast of Alaska, has grown to 500 miles across,and is the biggest and longest-lasting temperature anomaly in the historical record. …Scientists aren’t sure exactly what caused the blob, but they think it may have links to everything from the California drought to the large numbers of starving sea lion pups who’ve washed up on west coast shores. The temperature change also has caused creatures from tropical and temperate zones to wander north into places where they’re not usually found, and others that normally stay far out at sea have ventured closer to the coast, according to this Seattle Times article…. http://news.discovery.com/earth/oceans/mysterious-warm-water-blob-in-pacific-wreaking-havoc-150617.htm

2008 May 1. Next decade ‘may see no warming’. By Richard Black, Environment correspondent, BBC News website. The Earth’s temperature may stay roughly the same for a decade, as natural climate cycles enter a cooling phase, scientists have predicted. A new computer model developed by German researchers, reported in the journal Nature, suggests the cooling will counter greenhouse warming. However, temperatures will again be rising quickly by about 2020, they say.
Other climate scientists have welcomed the research, saying it may help societies plan better for the future.
…The key to the new prediction is the natural cycle of ocean temperatures called the Atlantic Multidecadal Oscillation (AMO), which is closely related to the warm currents that bring heat from the tropics to the shores of Europe.
The cause of the oscillation is not well understood, but the cycle appears to come round about every 60 to 70 years.
…”One message from our study is that in the short term, you can see changes in the global mean temperature that you might not expect given the reports of the Intergovernmental Panel on Climate Change (IPCC),” said Noel Keenlyside from the Leibniz Institute of Marine Sciences at Kiel University.
His group’s projection diverges from other computer models only for about 15-20 years; after that, the curves come back together and temperatures rise.
…Modelling of climatic events in the oceans is difficult, simply because there is relatively little data on some of the key processes, such as the meridional overturning circulation (MOC) – sometimes erroneously known as the Gulf Stream – which carries heat northwards in the Atlantic.
…Looking forward, the model projects a weakening of the MOC and a resulting cooling of north Atlantic waters, which will act to keep temperatures in check around the world, much as the warming and cooling associated with El Nino and La Nina in the Pacific bring global consequences….

2008 Mar 1. HEAVY RAIN FLOODS SOUTH AMERICA. NASA Earth Observatory News. Persistent, heavier-than-normal rains throughout February and March 2008 triggered flooding across parts of northern and central South America. La Niña conditions in the Pacific may have caused the unusual rainfall.

2008 April 4. Global temperatures ‘to decrease’. By Roger Harrabin, BBC News environment analyst. Excerpt: La Niña caused some of the coldest temperatures in memory in China. Global temperatures this year will be lower than in 2007 due to the cooling effect of the La Niña current in the Pacific, UN meteorologists have said. The World Meteorological Organisation’s secretary-general, Michel Jarraud, told the BBC it was likely that La Nina would continue into the summer. This would mean global temperatures have not risen since 1998, prompting some to question climate change theory. But experts have also forecast a record high temperature within five years. ‘Variability’
La Niña and El Niño are two great natural Pacific currents whose effects are so huge they resonate round the world. El Niño warms the planet when it happens, La Niña cools it. This year, the Pacific is in the grip of a powerful La Niña. It has contributed to torrential rains in Australia and to some of the coldest temperatures in memory in snow-bound parts of China.
Refers to the extensive cooling of the central and eastern Pacific …Increased sea temperatures on the western side of the Pacific means the atmosphere has more energy and frequency of heavy rain and thunderstorms is increased. ….Typically lasts for up to 12 months and generally less damaging event than the stronger El Niño.

2008 January 10. NASA Observes La Niña: This ‘Little Girl’ Makes a Big Impression Excerpt: Cool, wet conditions in the Northwest, frigid weather on the Plains, and record dry conditions in the Southeast, all signs that La Niña is in full swing. With winter gearing up, a moderate La Niña is hitting its peak. And we are just beginning to see the full effects of this oceanographic phenomenon, as La Niña episodes are typically strongest in January. A La Niña event occurs when cooler than normal sea surface temperatures form along the equator in the Pacific Ocean, specifically in the eastern to central Pacific. The La Niña we are experiencing now has a significant presence in the eastern part of the ocean. The cooler water temperatures associated with La Niña are caused by an increase in easterly sea surface winds. Under normal conditions these winds force cooler water from below up to the surface of the ocean. When the winds increase in speed, more cold water from below is forced up, cooling the ocean surface. “With this La Niña, the sea-surface temperatures are about two degrees colder than normal in the eastern Pacific and that’s a pretty significant difference,” says David Adamec of NASA’s Goddard Space Flight Center, Greenbelt, Md. “I know it doesn’t sound like much, but remember this is water that probably covers an area the size of the United States. It’s like you put this big air conditioner out there – and the atmosphere is going to feel it.” While this “air conditioner” may be located in the equatorial Pacific Ocean, it has a great influence on the weather here in the United States and across the globe. …The Northwest generally experiences cooler, wetter weather during a La Niña. On the Great Plains, residents normally see a colder than normal winter and southeastern states traditionally experience below average rainfall. …The increased circulation that brings up cold water from below also brings up with it nutrients from the deeper waters. These nutrients feed the organisms at the bottom of the food chain, starting a reaction that increases life in the ocean. NASA’s SeaWiFS satellite documented this increase in hytoplankton during the last La Niña period in 1998. La Niña and El Niño episodes tend to occur every three to five years. La Niñas are often preceded by an El Niño, however this cycle is not guaranteed. The lengths of La Niña events vary as well. “We need to watch to see if this La Niña diminishes, because they can last for multiple years….

2006 September 23. Nature provides “ecosystem services”. Earth & Sky Radio Show.

2006 September 19. El Nino mystery solved, monsoon forecasts improved. Earth & Sky Radio Show.

2005

1 December 2005. Alarm over dramatic weakening of Gulf Stream. Ian Sample, science correspondent, The Guardian Excerpt: Slowing of current by a third in 12 years could bring more extreme weather. Temperatures in Britain likely to drop by one degree in next decade. The powerful ocean current that bathes Britain and northern Europe in warm waters from the tropics has weakened dramatically in recent years, a consequence of global warming that could trigger more severe winters and cooler summers across the region, scientists warn today. Researchers on a scientific expedition in the Atlantic Ocean measured the strength of the current between Africa and the east coast of America and found that the circulation has slowed by 30% since a previous expedition 12 years ago. The current, which drives the Gulf Stream, delivers the equivalent of 1m power stations-worth of energy to northern Europe, propping up temperatures by 10C in some regions. … Previous expeditions to check the current flow in 1957, 1981 and 1992 found only minor changes in its strength, although a slowing was picked up in a further expedition in 1998…. If the current remains as weak as it is, temperatures in Britain are likely to drop by an average of 1C in the next decade, according to Harry Bryden at the National Oceanography Centre in Southampton who led the study. …The current is essentially a huge oceanic conveyor belt that transports heat from equatorial regions towards the Arctic circle. Warm surface water coming up from the tropics gives off heat as it moves north until eventually, it cools so much in northern waters that it sinks and circulates back to the south. There it warms again, rises and heads back north. The constant sinking in the north and rising in the south drives the conveyor. Global warming weakens the circulation because increased meltwater from Greenland and the Arctic icesheets along with greater river run-off from Russia pour into the northern Atlantic and make it less saline which in turn makes it harder for the cooler water to sink, in effect slowing down the engine that drives the current….

2004

1 December 2004. NASA SATELLITES WITNESSED EL NIÑO CREEP IN FROM THE INDIAN OCEAN. NASA Earth Observatory News. El Niño has fascinated people for centuries, and continues to interest people around the world, because it changes global weather patterns….Just in time for this Christmas, an index created to see the development of El Niño events received the approval of the scientific community. Scott Curtis, a NASA-funded scientist from East Carolina University in Greenville, N.C. and colleagues, created an index using satellite data of rain and winds in the eastern Indian Ocean that accurately predicted the arrival of the 2002-2003 El Niño. … Curtis … and Robert Adler, George Huffman and Guojun Gu, all of NASA’s Goddard Space Flight Center, Greenbelt, Md. used NASA’s Tropical Rainfall Measuring Mission (TRMM) and QuikScat satellite data ranging from November 2001 to March 2002. …The researchers developed the El Niño Onset Index (EOI) using the rainfall data alone. “Because the rainfall data has been a consistent indicator of an on-coming El Niño, as compared to the wind data, only the rainfall data was used to construct the EOI,” 

8 November 2004. NASA RELEASE: 04-369. TRMM Satellite Proves El Niño Holds the Reins on Global Rains.NASA scientists recently found the El Niño Southern Oscillation (ENSO) is the main driver of the change in rain patterns all around the world. The NASA and Japan Aerospace Exploration Agency (JAXA) Tropical Rainfall Measuring Mission (TRMM) satellite has enabled scientists to look around the globe and determine where the year-to-year changes in rainfall are greatest. By studying the rain patterns in these areas over the past 50 years, with rain gauge data prior to 1998, they established the main component of this change in global rainfall is directly correlated with the El Niño Southern Oscillation. The study appeared in a recent issue of the Journal of Geophysical Research-Atmospheres. 

15 April 2004. NASA RELEASE: 04-130. SATELLITES RECORD WEAKENING NORTH ATLANTIC CURRENT. A North Atlantic Ocean circulation system weakened considerably in the late 1990s, compared to the 1970s and 1980s, according to a NASA study. Sirpa Hakkinen, lead author and researcher at NASA’s Goddard Space Flight Center, Greenbelt, Md. and co-author Peter Rhines, an oceanographer at the University of Washington, Seattle, believe slowing of this ocean current is an indication of dramatic changes in the North Atlantic Ocean climate. The study’s results about the system that moves water in a counterclockwise pattern from Ireland to Labrador were published on the Internet by the journal Science on the Science Express Web site at: http://www.sciencexpress.org. The current, known as the sub polar gyre, has weakened in the past in connection with certain phases of a large-scale atmospheric pressure system known as the North Atlantic Oscillation (NAO). 

8 March 2004. From science@NASA — A Chilling Possibility. By disturbing a massive ocean current, melting Arctic sea ice might trigger colder weather in Europe and North America. 

5 January 2004. NASA RELEASE: 04-007. EL NINO-RELATED FIRES INCREASE GREENHOUSE GAS EMISSIONS. Year-to-year changes in concentration of carbon dioxide and methane, two important greenhouse gases in the atmosphere, can be linked to fire activity associated with the El Nino-La Nina cycle, according to a study conducted by a team of NASA scientists and other researchers…. Scientists today are trying to understand the relationship between the carbon cycle and the climate system. The carbon cycle is the movement of carbon, in its many forms, among the biosphere, atmosphere, oceans and the geosphere. The cycling of carbon affects the amount of carbon-based greenhouse gases in the atmosphere and thus the Earth’s climate. This study shows carbon loss in the biosphere over the next several centuries may be sensitive to the intensity and variability of El Nino-induced droughts. 

2003

9 September 2003. El Nino damage in California. NASA’s Earth Observatory. In anticipation of the 1997-98 El Niño, the U.S. Federal Emergency Management Agency spent approximately $165 million to prepare for storms and heavy rain in California. Local governments distributed sandbags to residents for flood protection, established volunteer programs to remove debris from storm drains, monitored high flood risk areas, and provided special training to damage-control teams. All of this preparation was possible because the 1997-98 El Niño had been forecast six months in advance.

14 March 2003. A Quirky El Niño. (science@NASA) The 2002-03 El Niño has resisted stereotypes with its unpredictable behavior. …Sometimes Earth scientist Bill Patzert wishes he had a degree in psychology. It might help him understand El Niño. “Every El Niño has a personality all its own, and the latest one has been very quirky,” says Patzert, who works at NASA’s Jet Propulsion Laboratory. “Here in southern California we expect El Niño to bring heavy rains. But the weather this winter has had a split-personality, alternating between warm and dry months to very cold and wet months.”

2002

1 August 2002. SATELLITES REVEAL A MYSTERY OF LARGE CHANGE IN EARTH’S GRAVITY FIELD — Satellite data since 1998 indicates the bulge in the Earth’s gravity field at the equator is growing, and scientists think that the ocean may hold the answer to the mystery of how the changes in the trend of Earth’s gravity are occurring. Goddard Space Flight Center RELEASE: 02-147

2001

11 April 2001. NASA DEMONSTRATES HOW EARTH’S GLOBAL HEAT ENGINE DRIVES PLANT GROWTH. Scientists at NASA GSFC have assembled the first long-term global data set that demonstrates the connection between changing patterns of sea surface temperature and patterns of plant growth across the Earth’s landscapes.

6 March 2001. AFTER THREE STRIKES, IS LA NINA OUT? Last Autumn scientists thought La Nina had faded, but recent NASA satellite images revealed La Nina-like conditions lurking in the Pacific for the third year in a row. Will they linger a fourth? Some climate models predict La Nina will vanish in 2001 and that a weak El Nino could take its place. A shift from La Nina to El Nino conditions would likely trigger more rainfall in California where swelling rivers will increase the output of hydroelectric dams, providing the state with some much needed electricity. La Nina-like conditions that have persisted in the Pacific Ocean for three years might finally subside this Fall. The change could pave the way for a weak El Nino — and a surge of hydroelectricity for power-starved California.

4 January 2001. RAINFALL CHANGE MAY GIVE EARLIER SIGNAL OF EL NINO. A decrease in rainfall over the Indian Ocean may give the world the earliest signal that a strong El Nino is about to start. US Global Change Research Program (USGCRP)

1999

August 1999. El Niño. NASA Earth Science Enterprise Series, Fact Sheet: NF-211 [97KB PDF] El Niño effects are not limited to the disturbed areas off of Peru and Ecuador. They can be transmitted great distances. In many parts of the world, the disruption of normal climate can have tragic and/or profound economic consequences. 

June 1999. La Niña. NASA Earth Science Enterprise Series, Fact Sheet: FS-1998-08-017-GSFC [250KB PDF] The coupled atmosphere-ocean phenomenon known as El Niño is frequently followed by a period of normal conditions in the equatorial Pacific Ocean. Sometimes, but not always, El Niño conditions give way to the other extreme of the El Niño-Southern Oscillation (ENSO) cycle. This cold counterpart to El Niño is known as La Niña, Spanish for “the girl child.” 

1998

February 1998. Using Satellites to Track Rift Valley Fever [200KB PDF NASA Lithograph] Rift Valley Fever (RVF), at least in the African country of Kenya, has been well known for over 60 years. As early as 1913, a disease fitting the description of RVF was blamed for the loss of sheep in the Rift Valley in kenya. However, it was not until scientists studied an outbreak of the disease in 1931 that a virus was isolated and shown to cause the disease. By using satellites to closely monitor the vegetation in the region affected by increased rainfall, scientists can identify likely habitats for the mosquitoes that carry the RVF virus, and provide advance warning of large-scale outbreaks of the disease.

1997-98 El Niño [405KB PDF NASA Lithograph] This image shows the progression of the 1997-98 El Niño as derived from the TOPEX/Poseidon satellite.