According to the Australian Government Bureau of Meteorology, the El Niño phenomenon continues to persist in the tropical Pacific. Atmospheric and oceanic indicators of the El Niño-Southern Oscillation (ENSO) reflect that the El Niño phenomenon has peaked and is now declining. Currently, El Niño may still continue to impact global weather and climate. Climate model predictions indicate that by the fall of 2024, sea surface temperatures (SSTs) in the tropical Pacific are expected to return to neutral levels of the El Niño-Southern Oscillation (ENSO).

Figure 5.5 shows the evolution of the standard Southern Oscillation Index (SOI) values from January 2023 to January 2024. Over the past four months, the SOI values were at lower levels around October and November (around -7), followed by a continuous upward trend until January. By December and January, the SOI has risen to neutral levels, indicating a decline in the El Niño phenomenon.

Figure 5.5 Monthly SOI-BOM time series from January 2023 to January 2024 (Source: http://www.bom.gov.au/climate/enso/soi/)

Another commonly used measure of El Niño events is called the Oceanic Niño Index (ONI). Figure 5.6 shows the locations of several NINO indices. An analysis of Table 5.2 reveals that during this four-month period, all three regions (NINO3, NINO3.4, and NINO4) have positive values, indicating sea surface temperatures above average levels. It is noteworthy that the positive values of the ONI index suggest the presence of El Niño conditions in the tropical Pacific region during this time. However, the absolute value in January 2024 is smaller compared to the preceding three months, suggesting a potential weakening or transition to neutral conditions.

Figure 5.6 Map of NINO Region（Source: https://www.ncdc.noaa.gov/teleconnections/enso/sst）

Table 5.2 ONI (°C) Anomaly Values from October 2023 to January 2024(Source:https://www.cpc.ncep.noaa.gov/data/indices/sstoi.indices)

Sea surface temperatures (SSTs) for January 2024 (Figure 5.7) were higher than the average level across the entire tropical Pacific. Between 10°S and 10°N, the sea temperature anomaly exceeds 1°C, warmer than the long-term (1961-1990) average in most areas along the equator. In comparison to December 2023, there is a slight decrease in sea temperature anomalies in the eastern and central-eastern Pacific.

According to the latest forecasts from NOAA's Climate Prediction Center, there is a probability of 79% that the El Niño phenomenon may transition to ENSO-neutral conditions between April and June 2024.

Figure 5.7 Monthly temperature anomalies for January 2024 (Source:http://www.bom.gov.au/climate/enso/wrap-up/#tabs=Sea-surface)

Global Impact 

El Niño has varying effects on different regions, typically bringing drier conditions to certain areas of Australia, Southeast Asia, and South Africa, increasing the risk of agricultural production and wildfires. Pacific airflows and tropical cyclone activity may also be affected.

The World Meteorological Organization (WMO) has confirmed that 2023 is the hottest year on record. The WMO estimates that the global temperature in 2023 exceeded the average level of 1850-1900 by 1.45±0.12°C, surpassing the record-warm years of 2016 and 2020, which were 1.29±0.12°C and 1.27±0.12°C, respectively. During the period from April 2023 to January 2024, global sea surface temperatures (SST) reached the highest levels ever recorded.

Climate change is leading to an increase in the frequency of extreme heat events. In recent decades, the proportion of high-intensity, short-duration rainfall events has also been on the rise, especially during the rainy season, with a larger proportion observed in the northern regions of Australia.

Extreme heat events and extreme fire weather associated with warming have also seen an increase (Figure 5.8).

Figure 5.8 Northern Kenya is currently experiencing drought

In some regions of South America, recent high temperatures and dry weather have led to devastating forest wildfires in central Chile. Argentina experienced a heatwave from January 21 to 31, while the capital of Chile, Santiago, recorded its third-highest temperature in history on January 31, surpassing 37 degrees Celsius. In early February, the high temperatures in central Chile triggered wildfires, resulting in at least 131 deaths and over 300 people missing or unaccounted (Figure 5.9). This is the most severe disaster Chile has faced since the 8.8-magnitude earthquake in 2010.

Figure 5.9 On February 3rd, a wildfire in Biobío del Mar, Chile, reduced houses to rubble and ashes