La Nina means Little Girl in Spanish. According to National Ocean Service of National Oceanic and Atmospheric Administration (NIAA), US Department of Commerce, La Nina is also sometimes called El Viejo, or anti-El Nino.
The phenomenon begins when the atmosphere reacts to a cooler patch of water over the Pacific Ocean. Signs have been emerging for months that the pattern was likely forming, marking the world’s second La Nina in a row.
La Nina – like its counterpart, El Nino – usually peaks in the Northern Hemisphere’s winter, but its effects can trigger widespread consequences across the globe.
India has been witnessing extreme weather conditions over the past few weeks. This can be attributed to various causes, including warming of the seas, unabated development and delayed withdrawal of the monsoon, PTI reported.
The southwest monsoon withdrew from the country on Monday, making it the seventh-most delayed retreat since 1975, according to the India Meteorological Department (IMD).
The southwest monsoon retreated on or after October 25 five times between 2010 and 2021 in 2017, 2010, 2016, 2020 and 2021, the IMD data showed.
The southwest monsoon started receding from west Rajasthan and adjoining Gujarat on October 6, making it the second-most delayed withdrawal since 1975.
The withdrawal of the southwest monsoon from northwest India usually begins from September 17.
The monsoon withdrawal started on September 28 last year, October 9 in 2019, September 29 in 2018, September 27 in 2017 and September 15 in 2016, according to IMD data.
The country received “normal” rainfall during the four-month southwest monsoon season from June to September.
M Rajeevan, former Ministry of Earth Sciences secretary, who has been studying the southwest monsoon for more than three decades, said warming of seas around India is another factor behind the delayed withdrawal of the monsoon.
He told PTI that the warming of the Bay of Bengal and Arabian Sea helps in forming a cyclonic circulation. This year, it is aided by La Nina conditions — the phenomenon is associated with the cooling of the Pacific waters and usually results in good rainfall activity — and some remnants of cyclonic circulation from the Pacific Ocean.
What happens during La Nina?
Explaining the phenomenon, NOAA said it forms after reverse interaction of weather conditions with trade winds, the permanent east-to-west prevailing winds that flow in the Earth’s equatorial region.
During normal conditions in the Pacific Ocean, trade winds take warm water from South America towards Asia. To replace that warm water, cold water rises from the depths, and the is called upwelling.
La Nina is one of the two opposing climate patterns that breaks these normal conditions.
Strong currents during La Nina
During La Nina, trade winds are even stronger than usual, pushing more warm water toward Asia, said NOAA. This leads to increasing in upwelling off the west coast of the Americas, which brings cold, nutrient-rich water to the surface.
These cold waters in the Pacific push the jet stream northward. NOAA added that La Nina can lead to a more severe hurricane season.
How long do these weather phenomenon last?
Episodes of La Nina typically last nine to 12 months, but can sometimes last for years. Such events occur every two to seven years, on average, but they don’t occur on a regular schedule. Generally, El Nino occurs more frequently than La Nina.
A weather phenomenon that typically delivers harsher winters is on the way and expected to add to Asia’s energy crisis.
The La Nina pattern, which forms when equatorial trade winds strengthen to bring colder, deep water up from the bottom of the sea, has emerged in the Pacific. That typically spells below-normal temperatures in the northern hemisphere and has prompted regional weather agencies to issue warnings about a frigid winter.
Several nations and particularly China, the top energy consumer, are grappling with surging fuel prices and for some, power shortages or curbs on supply to heavy industry. Coal and gas prices are already elevated and a bitter winter will add heating demand that’ll likely spur further gains.
“We are expecting temperatures to be colder than normal this winter across northeastern Asia,” said Renny Vandewege, a vice president of weather operations at data provider DTN. “Weather forecast data is a critical component of predicting how much energy load will be required.”
Here’s the outlook for some key nations:
Temperatures plunged early last week across most of eastern China, and are already colder than usual in some northern areas, according to the country’s National Climate Center. Provinces including Heilongjiang, Shaanxi and Shanxi began the winter heating season between four and 13 days earlier than in previous years. Local government-controlled systems — typically powered by coal or gas — are fired up to warm residents’ homes in many areas.
Extreme weather conditions could happen more regularly as a result of global warming, according to Zhi Xiefei, atmospheric science professor at Nanjing University of Information Science & Technology. “Cold waves could lead to greater temperature drops, but unusual warm events could also appear,” Zhi said.
The climate center expects the country to enter La Nina conditions this month, the official Xinhua News Agency said on Saturday.
Japan will likely see lower than normal temperatures next month, according to the Japan Meteorological Agency, which had earlier forecast a 60% chance of a La Nina over the autumn-winter period. The nation, which has been relatively insulated from the energy crisis, is staying vigilant after last year’s deep freeze that saw wholesale power prices spike.
Utilities were caught without enough fuel as demand surged last winter, forcing them to buy costly spot liquefied natural gas shipments. The trade ministry has already been meeting with major power, gas and oil firms to prepare for the winter months, and LNG stockpiles held by Japan’s major electricity providers are currently about 24% above the four-year average.
South Korea will see colder weather in the first half of winter, and is also likely to be impacted by the effects of La Nina, according to the country’s meteorological administration. The country saw its first snow of the season 15 days earlier than last year amid an unusually cold October.
The nation’s government is already taking steps to bolster fuel supply and mitigate the impact of higher prices. Fuel taxes and LNG import tariffs will be temporarily lowered, Vice Finance Minister Lee Eog-weon said Friday.
Temperatures in India are expected to fall to as low as 3 degrees Celsius (37 Fahrenheit) in some northern areas in January and February before recovering. Unlike in other nations, cooler weather typically leads to lower energy consumption as demand for air conditioning wanes.
Most importantly, the nation is anticipating a drier period after the end of the monsoon season. Key coal mining regions suffered flooding in recent months that triggered a squeeze on supply of the fuel used to produce about 70% of the nation’s electricity.
Aside from La Nina events, there are other factors that can impact the region’s winter weather, according to Todd Crawford, director of meteorology at Atmospheric G2. Climate change has led to a lack of sea ice in the Arctic’s Kara Sea, which may be contributing to high pressure ridging in that area. This leads to downstream colder conditions across northeast Asia, “like what happened last winter,” he said.
There are also indications the polar vortex a girdle of winds that bottle up cold at the pole could be weaker than normal at the start of winter, which would allow frigid air to spill south, Crawford said.
Putting all that together, we think the best window for big cold in northeast Asia this winter is in the late November to mid-January window,” he said. “That is where we think the greatest risk lies.”