Date : 07/09/2023

Relevance – GS Paper 1 – Geography

Keywords – El nino, La nina, ENSO, Walker Circulation,

Context –

A recent scientific study has raised concerns regarding the profound impact of human activities on the duration and behavior of El Nino and La Nina events, which are pivotal climate phenomena. This research has identified significant changes in the behavior of the Walker Circulation, an essential atmospheric component driving these events, particularly since the onset of the industrial era. These alterations in the Walker Circulation suggest that the occurrence of multi-year El Nino and La Nina events could become more frequent in the future. This potential shift in climate patterns holds the potential to elevate the risks associated with droughts, wildfires, heavy rainfall, and floods, demanding our attention and mitigation strategies.

Insights Offered by Recent Research Findings

The Walker Circulation, intricately tied to the El Nino-Southern Oscillation (ENSO) system, plays a pivotal role in shaping weather patterns worldwide. Researchers embarked on a mission to assess whether the emissions of greenhouse gasses had exerted an influence on this critical climate driver. Their findings have unveiled a subtle deceleration in the transition from El Nino to La Nina over time. This deceleration implies that multi-year climate patterns might become increasingly prevalent, posing heightened risks across the globe, from extended droughts to severe flooding, intense fires to heavy rainfall. Importantly, while the overall strength of the Walker Circulation has not witnessed a decline as of now, there exists a speculative concern regarding the potential weakening of this atmospheric component due to elevated levels of carbon dioxide. Additionally, various climate models have projected a potential decline in the Walker Circulation's strength by the end of this century.

This study further underscores a compelling correlation between volcanic eruptions and the weakening of the Walker Circulation, which often leads to El Nino-like conditions. Historical data points to three significant El Nino events in the twentieth century that were preceded by volcanic eruptions: Mount Agung in 1963, El Chichón in 1982, and Mount Pinatubo in 1991.

Walker Circulation:

The Walker Circulation, a large-scale atmospheric circulation pattern primarily located in the tropical Pacific region of Earth, holds the reins in shaping climate and weather patterns across the tropics and beyond. A weaker Walker Circulation corresponds with the onset of El Nino, while a more robust circulation signals the advent of La Nina.

El Nino:

El Nino, meaning "Little Boy" in Spanish, is a climate pattern characterized by the unusual warming of surface waters in the Tropical Pacific Ocean. It occurs more frequently than its counterpart, La Nina, and is notorious for suppressing monsoon rainfall in India. El Nino results from the weakening or reversal of trade winds in the tropical Pacific, which typically blow from east to west, pushing warm surface waters towards the western Pacific.

La Nina:

La Nina, which translates to "Little Girl" in Spanish and is sometimes referred to as El Viejo, anti-El Nino, or simply "a cold event," presents a contrasting picture. It involves the abnormal cooling of the Tropical Pacific Ocean and aids in rainfall over India. The strengthening of the trade winds in the tropical Pacific Ocean during La Nina events intensifies the normal east-to-west flow of warm surface waters across the equatorial Pacific. This, in turn, results in cooler-than-average sea surface temperatures in the central and eastern equatorial Pacific.

El Nino-Southern Oscillation (ENSO):

ENSO is a complex climate phenomenon arising from the intricate interplay between oceanic and atmospheric conditions. Its "southern oscillation" component pertains to disparities in sea-level air pressure over the western and eastern Pacific Oceans. El Nino and La Nina represent the warm and cool phases of the ENSO cycle, which typically undergo periodic shifts every 2 to 7 years. While La Nina events may persist for up to three years, it is relatively rare for El Nino events to extend beyond a year. The emergence of multi-year El Nino and La Nina events, as experienced in 2023 with the conclusion of a three-year La Nina, is an unusual and noteworthy phenomenon.

Potential Consequences of Increasing Multi-Year El Nino and La Nina Phenomena

The advent of more frequent and extended multi-year El Nino and La Nina events can potentially reshape the global climate landscape, heralding a host of impacts across various sectors:

Elevated Incidence of Severe Weather Events:

These prolonged climate patterns have the potential to alter precipitation, temperature, wind patterns, and atmospheric pressure on a global scale. Consequently, we can anticipate a surge in the occurrence and severity of extreme weather events, ranging from debilitating droughts and catastrophic floods to scorching heat waves, bone-chilling cold snaps, ferocious storms, and devastating wildfires.

Natural Disasters:

Floods and Droughts:

Multi-year El Nino events can exacerbate the risk of protracted droughts followed by catastrophic flooding in diverse regions. Conversely, multi-year La Nina events may trigger excessive rainfall and flooding in some areas, only to be succeeded by prolonged periods of drought in others.

Tropical Cyclones:

The frequency and intensity of tropical cyclones are intrinsically linked to the dynamics of ENSO events. Multi-year ENSO phenomena can yield variations in cyclone activity across different ocean basins, thereby impacting the vulnerability of coastal regions.

Agriculture and Food Security:

Multi-year El Nino-induced droughts can substantially diminish crop yields, with far-reaching repercussions for global food supplies and prices. Conversely, multi-year La Nina events may enhance crop production in certain regions but concurrently result in crop damage due to excessive rainfall and waterlogging.

Economic and Societal Impacts:

• These prolonged ENSO events entail a gamut of economic and societal ramifications. The cumulative impact encompasses significant economic costs stemming from infrastructure damage, escalated energy demand, and disruptions to global trade in key commodities such as food and minerals.
• Changing weather patterns can significantly influence the spread of diseases. The prolonged droughts associated with multi-year El Nino events increase the risk of waterborne diseases, while extended La Nina periods raise concerns about the transmission of vector-borne diseases.

Ecological Ramifications:

Ecosystems:

Multi-year ENSO events place considerable stress on terrestrial and marine ecosystems. The consequences may manifest as coral bleaching, rampant forest fires, and disruptions to habitat stability. Ecosystems often grapple with the challenge of adapting to rapid and persistent shifts in temperature and precipitation patterns.

Biodiversity:

Shifts in environmental conditions can exert profound impacts on species distribution and survival, especially affecting those species sensitive to climatic variations. The repercussions ripple through ecosystems, ultimately affecting biodiversity and the delicate balance of ecological systems.

Conclusion

The recent study shedding light on the evolving behavior of the Walker Circulation and the implications for multi-year El Nino and La Nina events underscores the critical need for proactive climate mitigation and adaptation strategies. As these phenomena exert far-reaching consequences on weather patterns, natural disasters, agriculture, economies, public health, and ecosystems, comprehensive efforts are essential to address the challenges posed by a changing climate.

Source – Down To Earth