Describe how upwelling can affect climate.

Remember the atmosphere and the hydrosphere - the oceans, are connected systems. They exchange energy and mass.

Deeper ocean waters are usually cooler than surface waters. Their upwelling means the surface waters will be cooler until they are also warmed up by the sun over time.

Cooler surface waters mean there is a lowered exchange of heat energy and water vapor from the oceans to the atmosphere in the region. The winds emanating from the region will therefore be cooler and drier affecting the climate of the area, including on the continent where the trade winds blow.

This phenomenon - the upwelling in the Pacific Ocean waters - is also the basis for the El Nino La Nina cycles.