World Meteorological Organization Declares Onset of El Niño Conditions

El Niño conditions have emerged in the tropical Pacific for the first time in seven years, increasing the likelihood of rising global temperatures and significant weather and climate disruptions.

According to the latest update from the World Meteorological Organization (WMO), there is a 90% probability that the El Niño event will persist through the latter half of 2023. Forecasts indicate that the event will be at least of moderate intensity. The WMO update incorporates analyses from global experts and forecast models.

WMO Secretary-General Prof. Petteri Taalas stated that the presence of El Niño significantly raises the chances of new temperature records being set, leading to more frequent and severe heat waves in various parts of the world, including oceanic regions. The declaration prompts governments to enhance preparations, aiming to mitigate potential impacts on public health, ecosystems, and economies. Early warning systems and proactive measures are crucial in addressing extreme weather events linked to this climate phenomenon to minimize harm to communities and infrastructure.

El Niño typically occurs every two to seven years and lasts between nine and twelve months. This natural climate pattern is characterized by the warming of ocean surface temperatures in the central and eastern tropical Pacific. However, its effects are now superimposed on long-term climate changes driven by human activities.

In anticipation of this event, a WMO report released in May projected a 98% probability that at least one of the next five years, as well as the five-year period overall, will surpass previous temperature records. The record set in 2016, when an exceptionally strong El Niño occurred, is likely to be exceeded.

The May report, led by the UK’s Met Office in collaboration with international partners, also estimated a 66% chance that the global annual near-surface temperature between 2023 and 2027 will temporarily exceed pre-industrial levels by more than 1.5°C for at least one year.

However, this does not imply a permanent exceedance of the 1.5°C threshold established in the Paris Agreement, which refers to long-term warming over multiple years. Instead, it underscores the urgent need for accelerated action to curb climate change in alignment with the targets set in the 2015 Paris Agreement, explained WMO Director of Climate Services Prof. Chris Hewitt.

Data from WMO’s State of the Global Climate reports highlight that 2016 remains the warmest year on record due to the combined effects of a powerful El Niño and anthropogenic greenhouse gas emissions. The impact of the current El Niño event on global temperatures is expected to be most pronounced in 2024.

In 2022, the global average temperature was approximately 1.15°C above the 1850-1900 baseline, influenced by the cooling effects of a prolonged La Niña event.

Expected Impacts of El Niño

Historically, El Niño events led to increased rainfall in parts of southern South America, the southern United States, the Horn of Africa, and Central Asia. Conversely, they often contribute to severe droughts in Australia, Indonesia, sections of southern Asia, Central America, and northern South America.

During the boreal summer, the warmer ocean temperatures associated with El Niño can intensify hurricane activity in the central and eastern Pacific while simultaneously reducing hurricane formation in the Atlantic Basin.

In general, El Niño exhibits the opposite effects of La Niña, which ended earlier in 2023.

Current Observations and Forecast

Since February 2023, monthly average sea surface temperature anomalies in the central and eastern equatorial Pacific have increased significantly. The anomaly shifted from -0.44°C in February to +0.47°C in May. By mid-June, warm anomalies had continued to rise, reaching +0.9°C.

Oceanic and atmospheric data collectively indicate the presence of El Niño conditions in the Pacific. However, some uncertainty remains due to incomplete coupling between ocean and atmosphere systems, a critical factor for sustaining and amplifying El Niño. It is expected that full coupling in the tropical Pacific will develop within approximately a month.

Global Seasonal Climate Update

El Niño and La Niña are key drivers of Earth’s climate system, but other factors also contribute. In addition to its well-established ENSO updates, WMO now issues Global Seasonal Climate Updates (GSCU), which assess the impacts of additional climate influences, including the North Atlantic Oscillation, the Arctic Oscillation, and the Indian Ocean Dipole.

The most recent update for July, August, and September 2023 indicates that above-average sea surface temperatures are expected over oceanic regions, leading to widespread predictions of elevated land temperatures. Without exception, positive temperature anomalies are projected across all land areas in both hemispheres.

Precipitation forecasts for the upcoming three months align with typical El Niño-related rainfall patterns.

The WMO ENSO and Global Seasonal Climate Updates incorporate data from WMO Global Producing Centres of Long-Range Forecasts. These resources are made available to assist governments, United Nations agencies, and decision-makers in climate-sensitive sectors in their preparation efforts to safeguard lives and economies.

National Meteorological and Hydrological Services (NMHSs) will continue monitoring El Niño’s development and its effects on temperature and precipitation at national and local levels. WMO will provide further updates as necessary in the coming months.