7-Oct-2019: India’s Vishnu Nandan among 300 researchers to join largest ever Arctic expedition

The 32-year-old polar researcher from Kerala will be the only Indian aboard the multidisciplinary drifting observatory for the Study of Arctic Climate (MOSAiC) expedition.

For four months from November, Vishnu Nandan will not see sunlight. He will be aboard the German research vessel Polarstern, anchored on a large sheet of sea ice in the Central Arctic, drifting along with it during the pitch-black Polar winter.

A native of Kerala’s capital Thiruvananthapuram, the 32-year-old polar researcher will be the only Indian among 300 scientists from across the world aboard the multidisciplinary drifting observatory for the Study of Arctic Climate (MOSAiC) expedition, which will help the researchers better understand the impact of climate change and aid in improved weather projections.

Spearheaded by the Alfred Wegener Institute in Germany, MOSAiC, the largest ever Arctic expedition in history , will be the first to conduct a study of this scale at the North Pole for an entire year. Previous studies have been of shorter periods as the thicker sea ice sheets prevent access in winter. This research vessel has thus locked itself into a large sea ice sheet, before the winter, and will drift along with it. A suitable sea ice sheet (floe) was identified two days ago.

Dr. Nandan, a remote sensing scientist, will travel in a Russian icebreaker ship from the Norwegian port of Tromso in November to join the Polarstern on its second leg. The aim of the expedition will be to parameterise the atmospheric, geophysical, oceanographic and all other possible variables in the Arctic, and use it to more accurately forecast the changes in our weather systems. My role as a radar remote sensing specialist is to deploy radar sensors on the sea ice surface and accurately measure the ice thickness and its variations.

He was the lead author of ground breaking studies, which found that satellite measurements of seasonal sea ice that formed over the Arctic every year were likely to be incorrect by a substantial degree, as the presence of salts on snow overlying sea ice had led scientists to overestimate the thickness of the Arctic sea ice.

This year, we have the second lowest sea ice extent in the past 50 years, accentuated by anthropogenic activities. With lesser ice cover, more of the Arctic Ocean is exposed to sunlight for longer periods, causing increase of temperatures across the Indian, Pacific and Atlantic Oceans. As the ocean gets warmer, it influences global weather patterns, causing changes in monsoon patterns and triggering more destructive cyclones. The data we will be gathering in this expedition related to these will be of immense use to the upcoming generation of young scientists.

23-Oct-2019: Climate Change is Making El Niños More Intense

Climate change is increasing the frequency of extreme El Niño events, leading to intensifying droughts, worsening floods, and shifting hurricane patterns, according to a new study published in the Proceedings of the National Academy of Sciences.

The study, led by scientists in China and the United States, examined data from 33 El Niños dating back to 1901. It found that since the 1970s, El Niños — a natural periodic warming in the Pacific Ocean that can change weather patterns globally — have been forming farther to the west in the Pacific Ocean, where temperatures are warmer. Strong El Niños can cause severe drought in dry climates such as Australia and India, intense flooding in wetter climates such as the Pacific Northwest and Peru, and causes more hurricanes to form in the Pacific and fewer in the Atlantic.

Before 1978, 12 of 14 El Niños formed east of the International Dateline. Since 1978, all 11 have formed in the central or western Pacific Ocean, a shift of hundreds of miles. There have been three “super” El Niños since the shift — in 1982, 1997, and 2015 — that broke new average temperature records and triggered catastrophic natural disasters. The 1997-1998 El Niño, for example, caused thousands of deaths from severe heat, flooding, drought, and coastal storms, and generated as much as $96 billion in damage, according to the United Nations.

If global temperatures keep rising, El Niños could continue to intensify, with major impacts on societies around the world. If the observed background changes continue under future anthropogenic forcing [human-induced global warming], more frequent extreme El Niño events will induce profound socioeconomic consequences.

18-Jul-2019: Using El Niño and Antarctic Oscillation data to predict air pollution levels in northern India

A team of researchers affiliated with several institutions in China and the U.S. has found that data from El Niño and Antarctic Oscillation events can be used to predict air pollution levels in northern India. The group describes their study of the historical impact of El Niño and Antarctic Oscillation events on weather in northern India and what they found.

In recent years, northern India has experienced poor air quality, particularly in the winter months, to the extent that the country has some of the worst air quality in the world—surpassing even China. Researchers have also noted that in some years, pollution levels seem worse than normal due to weather conditions. In this new effort, the researchers looked at two natural weather events that are known to have a clear impact on winter weather in northern India—El Niño and the Antarctic Oscillation.

El Niño is, of course, an event that involves a large band of warm water forming in the Pacific Ocean—such events have widespread weather impacts across multiple parts of the world. And the Antarctic Oscillation is a wind event caused by a low-pressure belt forming over Antarctica.

To better understand what impact either or both weather events might have on India's air pollution, the researchers collected data on both, covering the years 2003 to 2018. They then used the data to conduct statistical modeling as a way to assess their impacts on northern India. They report that El Niño events tend to result in reduced wind speeds in the region, which prevented airborne pollutants from moving out of heavily populated areas. They also found that Antarctic Oscillation events create stronger winds in some parts of northern India and weaken them in others, resulting in uneven impacts on pollution levels.

The researchers suggest that it is possible to use weather data collected for El Niño and Antarctic Oscillation events to provide government officials with a means of gauging pollution levels in northern India each year.

16-Jul-2019: El Niño could be losing steam

A weak El Nino prevailing in the Pacific Ocean since the start of this year is beginning to dissipate. Over the next two months, a fully neutral condition is likely to be restored in the Pacific Ocean.

While the weak warming condition continues to be present as of now, it had begun to decrease. SST (sea-surface temperature) anomalies across most of the eastern Pacific decreased during the month. Overall, oceanic and atmospheric conditions were consistent with a weakening El Niño.

A transition from El Niño to ENSO-neutral is expected in the next month or two, with ENSO-neutral most likely to continue through Northern Hemisphere fall and winter.

El Nino is a condition wherein the surface waters in the equatorial Pacific Ocean, off the coast of South America, become unusually warm. Its opposite condition, when it becomes unusually cold, is termed, La Nina. The two conditions influence weather events worldwide, including the Indian monsoon. El Nino is known to suppress rainfall during the monsoon months.

6-May-2019: El Niños becoming stronger

Australian scientists have developed an innovative method using cores drilled from coral to produce a world first 400-year long seasonal record of El Niño events, a record that many in the field had described as impossible to extract. The record published in Nature Geoscience detects different types of El Niño and shows the nature of El Niño events has changed in recent decades.

This understanding of El Niño events is vital because they produce extreme weather across the globe with particularly profound effects on precipitation and temperature extremes in Australia, South East Asia and the Americas.

The 400-year record revealed a clear change in El Niño types, with an increase of Central Pacific El Niño activity in the late 20th Century and suggested future changes to the strength of Eastern Pacific El Niños. There are even some early hints that the much stronger Eastern Pacific El Niños, like those that occurred in 1997/98 and 2015/16 may be growing in intensity.

This extraordinary result was teased out of information about past climate from coral cores spanning the Pacific Ocean, as part of Dr Freund's PhD research at the University of Melbourne and the Centre of Excellence for Climate Extremes. It was made possible because coral cores -- like tree rings -- have centuries-long growth patterns and contain isotopes that can tell us a lot about the climate of the past. However, until now, they had not been used to detect the different types of El Niño events.

This meant El Niño researchers were constrained by what they could say about El Niño behaviour because the instrumental record was too short and it was hard to judge whether recent decadal changes were exceptional.

The key to unlocking the El Niño record was the understanding that coral records contained enough information to identify seasonal changes in the tropical Pacific Ocean. However, using coral records to reconstruct El Niño history at a seasonal timescale had never been done before and many people working in the field considered it impossible.

After carefully refining the technique to reconstruct the signature of El Niño in space and time using new machine learning techniques, the scientists were able to compare recent coral results with the instrumental record. Dr Freund found a strong agreement between the coral cores and recorded events. This confirmation allowed the team to extend the record back in time.

Dr Freund and her team found there has been an unprecedented increase in the number of El Niños forming in the Central Pacific over the past 30 years, compared to all 30 year periods in the past 400 years. At the same time, the stronger Eastern Pacific El Niños were the most intense El Niño events ever recorded, according to both the 100-year long instrumental record and the 400-year long coral record.

As a result, Australian researchers have produced a world-first seasonal El Niño record extending 400 years and a new methodology that will likely be the basis for future climate research.

Having a better understanding of how different types of El Niños have affected us in the past and present, will mean we are more able to model, predict and plan for future El Niños and their wide-ranging impacts.

29-Mar-2019: IMD confirms weak El Nino conditions

The India Meteorological Department (IMD) has finally declared that weak El Nino conditions are prevalent in the equatorial Pacific Ocean. These conditions are likely to persist in early part of the summer season and likely to weaken thereafter.

El Nino, which is the unusual warming of the equatorial Pacific Ocean, disrupts global wind patterns affecting climatic conditions in tropical areas like Africa, sub-tropical areas like India as well as the extra-tropical areas like North America.

In India, there is a relationship between El Nino events and hotter than usual summers along with a decrease in rainfall during the monsoon. Most of the time, these events have also led to drought conditions.

The weak El Nino might have an effect on the onset and intensity of monsoon this year, an update on which is expected soon from the government of India.

In the 135 years between 1880 and 2014, around 90 per cent of all evolving El Nino years have seen below normal rainfall, and 65 per cent of them experienced droughts. In fact, six of the worst droughts in the country since 1871 have been triggered by El Nino — the most recent being in 2009. The last El Nino event that ended in 2016 had lasted for two years and caused heat waves all around the world, including India. The heat waves in 2015 and 2016 killed more than 2,500 people in India, and have been attributed to climate change — suggesting that El Nino was intensified by global warming.

The severe El Nino had also caused massive coral bleaching in the Great Barrier Reef and droughts in parts of Africa, South East Asia and South America. Last year, too, Australia underwent its worst drought in living memory — in regions like the New South Wales the drought was the worst in 400 years.

Weather agencies in other countries had declared weak El Nino conditions at the beginning of 2019. In January, Japan’s Meteorological Agency (JMA), which is also the Asian arm of the World Meteorological Organisation (WMO), said El Nino conditions were prevailing and that there was 80 per cent chance of an El Nino phenomenon staying till spring season of 2019.

The Climate Prediction Centre (CPC) of the National Weather Service in the United States of America also concluded, around the same time, that weak El Nino conditions had formed in the equatorial Pacific Ocean. In a March 14, 2019 update, the CPC says that “weak El Niño conditions are likely to continue through the Northern Hemisphere spring 2019 with an 80 per cent probability and summer with a 60 per cent probability”.

The preliminary impact of a weak El Nino can already be seen with the rising temperatures and heat waves across the country. In early March, the heat wave season began in many areas of Tamil Nadu, coastal Andhra Pradesh and Rayalaseema.

On March 6, Tamil Nadu’s Dharmapuri station recorded a maximum temperature of 40.2 degree Celsius which is the highest temperature ever recorded at the place in March. The previous record was 40 degree Celsius — recorded in 1996. In Andhra Pradesh, while two meteorological stations at Tirupati and Cuddapah in the Rayalaseema region recorded maximum temperatures of 40.4 degree Celsius and 40 degree Celsius, five other stations recorded temperatures above 38 degree Celsius. But then in late March an unusual heat wave affected Kerala, taking weather forecasters by surprise. It has killed four people till date and almost 300 people have suffered from sun burns. One third of these cases were reported on March 27.

The local IMD blamed the heat wave on El Nino. Temperature rise of one degree Celsius above normal are usual in pre-monsoon summer. But this time, it is up by 3 to 4 degrees Celsius, which is abnormal. Now the heat waves have spread to Gujarat, Maharashtra and Odisha as well. Heat waves are the third highest cause for deaths among natural disasters in India, after lightning strikes and earthquakes; but the Indian government does not consider it as a natural calamity.

In fact, the IMD came up with advisories for heat waves only in 2016 — the first time in the institution’s 140 year-history. The heat waves of 2015 and 2016 had killed 2,040 and 1,111 people across the country respectively. In nine out of the last 10 years (till 2017) India has suffered from heat waves which have killed close to 8,000 people. Andhra Pradesh and Telangana seem to be particularly vulnerable to deaths due to heat wave conditions.

30-Jan-2019: How will global warming affect El Niño in the 21st Century?

El Niño remains the largest climate phenomenon that occurs frequently producing droughts, floods, wildfires, dust and snow storms, fish kill, and even elevated risks of civil conflicts. The theatre of action for El Niño is the tropical Pacific Ocean but its global reach costs the global community tens of billion dollars each time.

El Niños occur every two-to-seven years with very strong El Niños occurring about every 15 years. How its frequency or the time between two events and strength will change because of global warming remains a grand challenge for climate models. This also impacts projections of future climate since El Niños redistribute the heat gathered by the ocean between two El Niño events to cause a mini global warming. The most recent projection of global warming impact on El Niño appeared in scientific journal Nature in December 2018.

El Niño is measured by an index that averages sea surface temperature anomalies over the central-eastern tropical Pacific. Each model delivers a slightly different rendition of El Niño compared to nature. This has been an issue in finding a consensus among models as far as the El Niño response to global warming is concerned. But by using a model-specific El Niño index to make room for the inter-model differences, the latest projection posits that strong El Niño’s and thus extreme weather events associated with such strong El Niño’s will increase in the coming decades.

The results should serve as a warning to the countries on all continents that suffer from these extreme weather events during strong El Niño events such as the ones during 1982-83, 1997-98 and 2015-16. However, some major caveats are in order. The first caveat is that the eagerly-awaited winter rain and snow storms over California did not occur over California during the latest extreme El Niño. It is thus unclear if global warming is already affecting El Niño and its remote impacts. Secondly, the models used for making future projections have not stood the test of time for their depiction of El Niño during the 20th century.

The mean state of the tropical Pacific has cold temperatures in the east around the Galápagos Islands because the trade winds blowing from the east to west diverge waters away from the equator and push them westward. The atmosphere warms westward, moving waters and piling it in the west. Warm waters favour atmospheric convection and produce over 5 meters of rain per year to the west of the Dateline to New Guinea. El Niño is a perturbation of this background state of cold east – warm west ocean with air rising in the west and sinking in the east.

During an El Niño, warm waters and rainfall move east towards Galapagos and bring copious amounts of rain and mudslides to the Americas while causing droughts in the west over Australia and Indonesia. Floods, droughts and other extremes also occur over many other regions of the globe. The response of El Niño to global warming depends on how this background state responds to global warming as well. Some models warm the eastern tropical Pacific more than the west while others produce a faster warming in the west. Whether the east warms faster or the west has serious consequences for global warming itself since the cold eastern Pacific soaks up a lot of heating from the atmosphere. A slower warming of the east would imply more heat uptake by the ocean and a slower global warming.

Unfortunately, available data is not sufficient to say with confidence how the tropical Pacific has responded to global warming till now. All available evidence for El Niño behavior during the Holocene or the Last Glacial Maximum indicates that El Niño is highly variable and its variability depends on weather noise over the western Pacific, volcanoes, impact of phytoplankton on penetration of solar radiation into the ocean, aerosols and so on. It is unclear if the impact of global warming on El Niño can easily be extracted considering its intrinsic tendencies and its depends on so many factors that are not easily predictable.

In this context, it is imperative that models be held to very stringent standards on their performance of El Niño behaviour during historic periods, especially the 20th century, as a test of their reliability for future projections. This would also be necessary for projecting other events such as droughts and floods.

For example, droughts over India are closely tied with El Niño and any projections of how droughts will respond to global warming will depend on how models perform in their historic depiction of El Niño’s as well as monsoons and how reliably they can project El Niño response to global warming in addition to how the models perform in reproducing floods and droughts of 20th century.

27-Nov-2018: WMO Update: 75-80% chance of El Niño within next 3 months

There is a 75-80% chance of an El Niño developing by February 2019, although it is not expected to be a strong event, according to the latest update from the World Meteorological Organization (WMO). Sea surface temperatures are already at weak El Niño levels in part of the tropical Pacific, although the corresponding atmospheric patterns have not yet materialized.

WMO accompanied the El Niño Update with a global seasonal climate update, which indicated that precipitation patterns predicted for December-February resemble those normally associated with El Niño. In some regions the precipitation response has been weak, however, or not in keeping with those typically associated with El Niño.

The El Niño/Southern Oscillation (ENSO) is a naturally occurring phenomenon involving  fluctuations of ocean surface temperatures in the equatorial Pacific, coupled with changes in the overlying atmospheric circulation. It has a major influence on weather and climate patterns over many parts of the world.

Sea surface temperatures in the east-central tropical Pacific have been at weak El Niño levels since October 2018. However, the atmosphere has not yet responded to this additional warmth, and the upper level winds, cloud and sea level pressure patterns do not yet reflect typical El Niño features.

Model forecasts suggest that this will change within the coming month or two. The chance of a full-fledged El Niño between December 2018 - February 2019 is estimated to be about 75-80%, and about 60% for it to continue through February-April 2019. Model predictions of the strength of the El Niño range from just a warm-neutral condition through to a moderate strength El Niño event, with sea surface temperatures peaking at approximately 0.8 to 1.2 degrees Celsius above average.

The chance for a strong event (sea surface temperatures in the east-central tropical Pacific rising to at least 1.5 degrees Celsius above average) is currently low.

“The forecast El Niño is not expected to be as powerful as the event in 2015-2016, which was linked with droughts, flooding and coral bleaching in different parts of the world. Even so, it can still significantly affect rainfall and temperature patterns in many regions, with important consequences to agricultural and food security sectors, and for management of water resources and public health, and it may combine with long-term climate change to boost 2019 global temperatures,” said Maxx Dilley, director of WMO’s Climate Prediction and Adaptation branch.

Scientific progress on the understanding and modelling of ENSO, underpinned by major observational programmes and coordinated research initiatives, has improved operational monitoring and prediction capabilities, helping society to prepare for associated hazards such as heavy rains, floods and drought.

WMO’s update is based on forecast models and expert interpretation from around the world. It is used by planners within the United Nations system, and complements information issued by National Meteorological and Hydrological Services and WMO Regional Climate Centres as a source of information for country-level decision-making by disaster managers, for planning in climate-sensitive sectors, and by governments.

Global seasonal climate update: WMO’s global seasonal climate update for December 2018 through February 2019 is based on an ensemble of global prediction models run by WMO-accredited centres around the world. It is currently in a trial phase.

A tilt of the odds towards above-normal surface-air temperature is forecast in most of Asia, Europe, North America, the Caribbean, Africa, Australia, the Indonesian archipelago, and South America. Exceptions include portions of mainly southern South America, much of southeastern North America, parts of northwestern Europe and part of south-central Asia. Most of the regions with above-normal tendencies also saw above-normal temperatures during August-October 2018.

An enhanced probability of below-normal precipitation is predicted in the Caribbean, central America, part of northern South America, the offshore islands of southeast Asia, the southern part of the Indonesian archipelago, some south Pacific islands, portions of southwest Africa and eastern equatorial Africa, subtropical southwest coastal South America and southern South America.

Above-normal precipitation is favoured in part of southern North America, part of southeast South America, part of northwest North America, central and northern Asia, part of southwest Asia, part of the eastern Maritime Continent, and part of Europe. Near-normal precipitation is favoured in parts of interior northern tropical Africa.

These global forecasts provide predictions of large-scale patterns, which need to be further calibrated and optimized to derive regional and national scale forecasts.  WMO Regional Climate Centres, Regional Climate Outlook Forums (RCOFs) and National Meteorological and Hydrological Services carry out these tasks to provide more detailed outlooks.

National Meteorological and Hydrological Services will continue to closely monitor changes in the state of ENSO over the coming months.

El Niño is often associated with warm and dry conditions in southern and eastern inland areas of Australia, as well as Indonesia, the Philippines, Malaysia and central Pacific islands such as Fiji, Tonga and Papua New Guinea.

In northern hemisphere winter, drier than normal conditions are typically observed over south-eastern Africa and northern Brazil. Wetter than normal conditions are typically observed along the Gulf Coast of the United States, the west coast of tropical South America (Colombia, Ecuador and Peru) and from southern Brazil to central Argentina. Parts of eastern Africa and southernmost parts of South Asia also usually receive above-normal rainfall.

El Niño is associated with milder winters in north-western Canada and Alaska due to fewer cold air surges from the Arctic – a result of a large-scale region of lower pressure centred on the Gulf of Alaska/ North Pacific Ocean.

It is important to stress that these are typical effects – not specific forecasts – and that actual conditions vary according to the strength and timing of the El Niño event. Other factors (such as the Indian Ocean Dipole or the North Atlantic Oscillation/Arctic Oscillation) can also have an important influence on seasonal climate.

Global-scale seasonal forecasts, including those of precipitation and surface temperature, are routinely produced by WMO accredited centres using sophisticated atmosphere-ocean coupled models, which take into account ENSO as well as other climate drivers.  There are now 13 WMO Global Producing Centres of Long Range Forecasts, whose products are consolidated by a Lead Centre of Long Range Forecast Multi Model Ensemble (https://www.wmolc.org/).