Final answer:
El Niño typically decreases monsoon rainfall as part of the ENSO cycle, altering atmospheric conditions and affecting global weather patterns. These changes can result in extreme weather and impact human health and economies reliant on agriculture and fishing.
Step-by-step explanation:
El Niño decreases monsoon rainfall in many regions around the world. This phenomenon is part of the El Niño Southern Oscillation (ENSO) cycle, which has significant impacts on global weather patterns. During El Niño events, a band of warm ocean water develops in the central and east-central equatorial Pacific, which leads to changes in atmospheric conditions including high air pressure in the western Pacific and low air pressure in the eastern Pacific. One of the effects of these changed atmospheric conditions is the alteration of the monsoon systems, particularly in the Asia-Pacific region, often resulting in decreased rainfall.
In addition to affecting monsoon systems, El Niño can cause extreme weather in various parts of the world, like droughts and floods, which can have repercussions on economies dependent on agriculture and fishing. While the focus here is on rainfall, El Niño's broader influence on weather can lead to a range of other consequences, including increased precipitation in some areas, the intensification of tropical storms, and potential effects on human health, such as the spread of diseases like the hantavirus.