Which mechanism drives ocean density and upwelling disruption during El Niño events?

💡 Explanation

During El Niño, weakened trade winds decrease westward surface current flow across the Pacific because reduced wind shear slows the normal upwelling of colder, nutrient-rich water. Therefore limited upwelling results as warmer surface water reduces density-driven circulation, rather than salinity changes, cyclone mixing, or glacial melt which involve other dynamics.

• Which risk increases when pyroclastic flow encounters meltwater?
• Which mass wasting process is amplified within a cirque containing thawing permafrost?
• Which deformation pattern emerges when thawing permafrost causes widespread episodic solifluction on moderately steep Arctic slopes?
• Which phenomenon causes offset landforms and frequent shallow earthquakes parallel in a transform plate boundary?
• Which risk increases when a large glacial lake outburst flood (GLOF) occurs toward lower elevations?
• Which mechanism causes seismic creep along a transform fault boundary?