The study looked at how rainfall in April and May in South China changed over decades and how it relates to sea surface temperatures in the Mid-West Pacific Ocean. They found that when rainfall was lower in April and May, the ocean temperatures were warmer in the previous year. This led to changes in air pressure and wind patterns, causing less rainfall in South China. The study also showed that warmer ocean temperatures led to weaker winds and less water vapor reaching South China, resulting in less rainfall.