The global natural phenomenon La Niña is over and “neutral” weather conditions will remain in the tropical Pacific for the next few months. Temperatures are expected to rise above average this summer, especially in the Northern Hemisphere, the World Meteorological Organization (WMO) reported.
Rainfall is also expected to be below average in many parts of the world, including Eastern Europe, the Mediterranean and North America.
With the La Niña phenomenon, it causes a cooling of the ocean surface in the central and eastern equatorial Pacific Ocean, which leads to changes in the tropical circulation of the atmosphere, namely wind, pressure and precipitation. The La Niña phenomenon is associated with a cooling phase, while the opposite phenomenon, El Niño, is associated with a warming phase.
The start of 2021 was relatively cool by today’s standards. But that shouldn’t give us a false sense of security.
At the same time, WMO experts emphasize that all natural climatic events are currently taking place in the context of human-induced climate change, which is leading to an increase in global temperatures and exacerbation of extreme weather conditions.
“La Niña has a temporary global cooling effect, which is most felt in the second year of this phenomenon. The start of 2021 was relatively cool by today’s standards. But this should not give us a false sense of security, we should not think that the process of climate change has stopped, ”said the head of WMO, Petteri Taalas.
“The concentration of carbon dioxide, which leads to global warming, remains at an all-time high. New projections released by WMO show that at least one year between 2021 and 2025 will be the warmest year on record, breaking the 2016 record for the strongest El Niño, is 90 %. ” he added.
WMO experts remind that El Niño and La Niña are the main, but not the only factors influencing the weather conditions. There are also such phenomena as, for example, the North Atlantic and Arctic oscillations.
The 2020-2021 La Niña event has ended and neutral conditions (neither El Niño or La Niña) are likely to dominate the tropical Pacific in the next few months, according to the WMO. Air temperatures are expected to be above average between June and August, especially in the northern hemisphere.
There is a 78% chance of neutral conditions in the tropical Pacific until July, decreasing to 55% by August-October, and with more uncertainty for the rest of the calendar year, according to WMO’s El Niño/La Niña Update.
La Niña refers to the large-scale cooling of the ocean surface temperatures in the central and eastern equatorial Pacific Ocean, coupled with changes in the tropical atmospheric circulation, namely winds, pressure and rainfall. It usually has the opposite impacts on weather and climate as El Niño, which is the warm phase of the so-called El Niño Southern Oscillation (ENSO).
However, all naturally occurring climate events now take place in the context of human-induced climate change, which is increasing global temperatures, exacerbating extreme weather and impacting seasonal rainfall patterns.
“La Niña has a temporary global cooling effect, which is typically strongest in the second year of the event. This means that 2021 has got off to a relatively cool start – by recent standards. This should not lull us into a false sense of security that there is a pause in climate change,” said WMO Secretary-General Prof. Petteri Taalas.
“Carbon dioxide concentrations remain at record high levels and so will continue to drive global warming. According to new predictions issued by WMO, there is a 90% likelihood of at least one year between 2021-2025 becoming the warmest on record. This would dislodge 2016 – a strong El Niño year – from the top ranking,” said Prof. Taalas.
Global Seasonal Climate Update
El Niño and La Niña are major – but not the only – drivers of the Earth’s climate system.
In addition to the long-established ENSO Update, WMO now also issues regular Global Seasonal Climate Updates (GSCU), which incorporate influences of all other major climate drivers such as the North Atlantic Oscillation, the Arctic Oscillation and the Indian Ocean Dipole.
The Global Seasonal Climate Update is based on forecasts from WMO Global Producing Centres of Long-Range Forecasts and is used to support governments, the United Nations, decision-makers and stakeholders in climate sensitive sectors to mobilize preparations and protect lives and livelihoods.
The WMO Global Seasonal Climate Update is based on an ensemble of global prediction models run by WMO-accredited centres around the world.
The WMO El Niño/La Niña Update is prepared through a collaborative effort between the WMO and the International Research Institute for Climate and Society (IRI), USA, and is based on contributions from experts worldwide.
The El Niño/La Niña Southern Oscillation (ENSO) has a major influence on climate patterns in various parts of the world. This naturally occurring phenomenon involves fluctuating ocean temperatures in the central and eastern equatorial Pacific, coupled with changes in the atmosphere. Scientific progress on the understanding and modelling of this phenomenon has improved prediction skills to within a range of one to nine months in advance, giving society the opportunity to prepare for associated hazards such as heavy rains, floods and drought.