Final answer:
La Niña is the weather system that is likely causing droughts in Australia and floods in parts of South America.
Step-by-step explanation:
If Australia is experiencing droughts and parts of South America are flooded, it is likely due to the weather phenomenon known as La Niña. La Niña refers to the cooling of the surface temperatures in the eastern Pacific Ocean, which affects global weather patterns. During La Niña, Australia experiences drier than normal conditions, leading to droughts, while South America may experience increased rainfall and floods.
Learn more about La Niña and its impact on global weather patterns