El Nino and +IOD expected to severely impact global weather in coming months

El Nino and +IOD expected to severely impact global weather in coming months
by Simon Mansfield
Sydney, Australia (SPX) Apr 18, 2023

Recent climate forecasts predict a strong El Nino and positive Indian Ocean Dipole (IOD) events to occur in the near future, potentially leading to significant impacts on global weather patterns, atmospheric and oceanic processes. Past combined events have had substantial impacts on weather patterns and natural disasters around the world, including floods, droughts, and extreme weather events.

El Nino, characterized by the warming of the equatorial Pacific Ocean, and the positive IOD, marked by warmer sea surface temperatures in the western Indian Ocean and cooler temperatures in the eastern Indian Ocean, influence global atmospheric circulation patterns. The interaction of these events can disrupt the typical east-to-west flow of trade winds, altering precipitation and temperature patterns worldwide.

During El Nino and positive IOD events, the Walker circulation, a large-scale atmospheric circulation pattern, weakens, leading to changes in rainfall distribution. The weakened circulation often results in reduced rainfall over parts of Indonesia, Australia, and southern Asia, while increased precipitation occurs in parts of eastern Africa, South America, and the western tropical Pacific.

As these events unfold, oceanic processes are also affected. El Nino can cause the thermocline, the boundary separating warm surface waters from cooler deep waters, to deepen in the eastern Pacific. This leads to increased nutrient availability and subsequent changes in marine life distribution. In contrast, during a positive IOD event, upwelling of nutrient-rich waters in the eastern Indian Ocean is suppressed, leading to reduced primary productivity and altered marine ecosystems.

These atmospheric and oceanic processes can exacerbate the impacts of El Nino and positive IOD events. For instance, the 1997 and 2015 combined events led to increased rainfall, flooding, and droughts in various regions, with devastating consequences for infrastructure, agriculture, and human life. Warmer ocean temperatures can further intensify extreme weather events, such as hurricanes, typhoons, and heavy rainfall, and contribute to coral bleaching and changes in marine biodiversity.

Climate change is expected to amplify the impacts of these events, as rising global temperatures and increased greenhouse gas emissions could lead to more frequent and severe extreme climate events. This highlights the urgent need for continued monitoring and research into these phenomena, as well as the development of robust planning and adaptation measures to address the challenges faced by vulnerable regions.