El Niño Strength Disputed Among Meteorological Agencies
The differing opinions on this year's El Niño highlight a fundamental issue in measuring the climate phenomenon - different methods used by meteorological agencies make direct comparisons challenging.
This year's El Niño has been described as "unprecedented by Britain's Met Office and the strongest ever observed by Japan's weather agency, but U.S. forecasters remain skeptical about its record-breaking status.
The differing opinions on the strength of this year's El Niño highlight a fundamental issue in measuring the climate phenomenon - different methods used by meteorological agencies make direct comparisons challenging.
Climate scientist Emily Becker from the University of Miami emphasizes that any assessment of El Niño's strength is complex and requires careful analysis. According to Becker, only after this year's event has passed will scientists be able to accurately determine its magnitude and place it within the context of historical climate patterns.
The Pacific Ocean's El Niño Southern Oscillation (ENSO) serves as a major driver of global climate variability, with trade winds normally blowing from east to west along the equator. This natural process pushes warm water from South America towards Asia, while cold water rises from the depths to replace it.
The natural process that drives El Niño events is complex and ongoing. As warm water from South America moves towards Asia, it creates a ripple effect on global weather patterns. The trade winds weaken and shift, causing warm water to be pushed back east towards the Americas.
This change in ocean heat distribution has far-reaching consequences for global climate conditions. Some regions become cooler and wetter due to the altered atmospheric circulation, while others experience increased temperatures and droughts. The shifting of ocean heat into the atmosphere is a key factor in shaping these regional weather patterns.
The Met Office has highlighted the significance of raw temperature readings in the Pacific Ocean. According to its observations, sea-surface temperatures in the central equatorial Pacific have exceeded levels recorded during previous El Niño events. This is a crucial indicator of the event's intensity and potential impact on global climate conditions.
However, there are different ways to measure an El Niño event's strength, including looking at anomalies rather than absolute temperatures. The Japan Meteorological Agency has taken this approach in declaring this year's El Niño the strongest on record based on sea surface temperature anomalies in the Nino3 region of the eastern Pacific.
The way El Niño is measured has been a topic of discussion among climate experts, particularly when it comes to determining what constitutes normal" temperatures in the Pacific Ocean.
The U.S. National Oceanic and Atmospheric Administration (NOAA) has shifted its approach with the introduction of the Relative Oceanic Niño Index (RONI), which takes into account how warm or cool the east-central Pacific is compared to the rest of the tropical ocean.
This change acknowledges that climate change is causing oceans worldwide to warm, making it necessary for the baseline temperature average to be updated regularly. The RONI index measures temperatures against a 30-year average, but also considers the difference in temperature between the east-central Pacific and other tropical regions.
The WMO is following suit by transitioning from its long-used Oceanic Niño Index (ONI), which compared temperatures to a static 30-year baseline that was updated every five years. This shift aims to better reflect the impacts of climate change on global weather patterns.
The old index used to measure El Niño and La Niña events has been found to be inconsistent, with some years producing stronger effects than their rating suggested.
NOAA's latest projections indicate that this year's El Niño could potentially become the strongest on record, surpassing those of 1982-83, 2015-16, and 1997-98. The organization is monitoring the three-month average RONI anomaly, which needs to reach 2.5C or higher for it to be considered a record-breaker.
The chances of this El Niño becoming the strongest on record are currently rated as high, but not yet certain.
Facts based on reporting originally published by Phys.org.
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