A La Nina would have significant consequences for global agriculture because it typically brings wetter weather to eastern Australia and southeast Asia and drier conditions to the Americas.
| Photo Credit: Ritu Raj Konwar/The Hindu

There are early signs that a La Nina weather event may form in the Pacific Ocean later this year, Australia’s weather bureau said on Tuesday.

A La Nina would have significant consequences for global agriculture because it typically brings wetter weather to eastern Australia and southeast Asia and drier conditions to the Americas.

The bureau said it had declared a “La Nina Watch”.

“When La Nina Watch criteria have been met in the past, a La Nina event has subsequently developed around 50% of the time,” it said.

Also Read | El Niño, La Niña and changing weather patterns 

La Nina events result from cooler sea surface temperatures in the Pacific. Warmer sea surface temperatures can cause an opposite weather phenomenon called El Nino, which occurred last year and lasted into early 2024.

“Sea surface temperatures in the central Pacific have been steadily cooling since December 2023,” the bureau said.

“The Bureau’s modelling suggests that ENSO will likely remain neutral until at least July 2024,” it said, using the formal name, the El Niño Southern Oscillation, that describes the switch between the two phases.

Japan’s weather bureau has said there is a 90% chance that the El Nino phenomenon will dissipate by the end of May.

Other forecasters have also heralded a La Nina later this year. Last week, Japan’s weather bureau said there was a 60% chance it would occur by November, and a U.S. government forecaster said there was a 69% chance that it would develop during July-September.

Pea plants are damaged by drought, due to the El Nino weather phenomenon in Madrid municipality near Bogota, Colombia, January 17, 2016.
| Photo Credit: Reuters

Latin American nations must be on high alert as the weather phenomenon known as El Nino rapidly switches over to La Nina, experts said on Thursday, leaving populations and crops little time to recover.

El Nino and its abundant rains could soon turn into droughts caused by La Nina as well as an intense hurricane season across South America, experts said at a panel organized by the United Nations’ Food and Agriculture Organization (FAO).

The full weather pattern involving El Nino, La Nina and a neutral phase typically lasts between two to seven years. But experts said that the transition period from El Nino to La Nina is getting shorter.

“We just saw it happen,” said Yolanda Gonzalez, director of the International Research Center for the El Nino Phenomenon. “A year ago we came out of a Nina, and in March there were already signs of a Nino.”

“Now in March, April there are signs of a Nina,” she added. “We haven’t been able to recover from the impact.”

In South America, the weather patterns can hit key crops such as wheat and corn, denting commodity-dependent economies.

The phenomenon is not caused by climate change, FAO’s technical team told Reuters, but experts have seen that the effects of the weather pattern, such as rainfall, heat waves and drought, have become more extreme.

The rapid transitions between El Nino and La Nina could also be correlated with climate change, FAO said, though scientists have yet to establish definitive causation.

“These abrupt changes, and the fact that these cycles are now almost overlapping, ultimately decreases the ability to adapt to the changes,” said Marion Khamis, FAO’s regional risk management specialist. “This implies a huge challenge.”

The Copernicus Climate Change Service said that every month since June last year has been the warmest such month on record.
| Photo Credit: AP

The world, last month, experienced the warmest February on record, with the average temperature being 1.77 degrees Celsius more than the February average for 1850-1900, the designated pre-industrial reference period, the European Union’s climate agency said on March 7.

The Copernicus Climate Change Service (C3S) also said that every month since June last year has been the warmest such month on record.

Scientists attribute the exceptional warming to the combined effects of El Nino — a period of abnormal warming of surface waters in the central Pacific Ocean — and human-caused climate change.

C3S last month said the global mean temperature breached the 1.5-degree Celsius threshold for an entire year for the first time in January. A permanent breach of the 1.5-degree Celsius limit specified in the Paris Agreement, however, refers to long-term warming over many years.

Explained | How El Nino could impact the world’s weather in 2023-24

According to climate scientists, countries need to limit the global average temperature rise to 1.5 degrees Celsius above the pre-industrial period to avoid the worst impacts of climate change.

Earth’s global surface temperature has already increased by around 1.1 degrees Celsius compared with the average in 1850-1900 — a level that has not been witnessed since 1,25,000 years, before the most recent ice age.

This warming is considered the reason behind record droughts, wildfires and floods worldwide. With an average temperature of 13.54 degrees Celsius, February 2024 was 0.12 degrees Celsius warmer than the previous warmest February in 2016, the EU’s climate agency said.

“The month was 1.77 degrees Celsius warmer than an estimate of the February average for 1850-1900, the designated pre-industrial reference period,” C3S said in an update.

The global average temperature for the last 12 months (March 2023–February 2024) is the highest on record, at 0.68 degrees Celsius above the 1991-2020 average and 1.56 degrees Celsius above the 1850-1900 pre-industrial average.

“The daily global average temperature was exceptionally high during the first half of the month, reaching two degrees Celsius above the 1850-1900 levels on four consecutive days (February 8–11),” C3S scientists said.

The average global sea surface temperature (SST) for February 2024 was 21.06 degrees Celsius, the highest for any month in the dataset. The previous high was in August 2023 (20.98 degrees Celsius).

C3S director Carlo Buontempo said, “February joins the long streak of records of the last few months. As remarkable as this might appear, it is not really surprising as the continuous warming of the climate system inevitably leads to new temperature extremes.

“The climate responds to the actual concentrations of greenhouse gases in the atmosphere so, unless we manage to stabilise those, we will inevitably face new global temperature records and their consequences,” Mr. Buontempo said.

The World Meteorological Organization on Tuesday said the 2023-24 El Nino has peaked as one of the five strongest on record and will continue to impact global climate in the coming months despite a weakening trend.

The United Nations agency also said above-normal temperatures are predicted over almost all land areas between March and May. The WMO said there is about a 60% chance of El Nino persisting during March-May and an 80% likelihood of neutral conditions (neither El Nino nor La Nina) from April to June.

There is a chance of La Nina developing later in the year, but those odds are currently uncertain, it said. Scientists closely tracking the development in India have said La Nina conditions setting in by June-August could mean monsoon rains would be better this year than in 2023.

El Nino — a periodic warming of the ocean surface in the central and eastern tropical Pacific Ocean — occurs every two to seven years on average and typically lasts nine to 12 months.

It is associated with increased rainfall in the Horn of Africa and the southern U.S., and unusually dry and warm conditions in Southeast Asia, Australia and southern Africa.