The researchers used a computer model to simulate the climate during the Silurian Period, around 430-424 million years ago. They found that the Earth was warmer with higher levels of CO2 in the atmosphere compared to today. The climate was influenced by the positioning of continents, creating different weather patterns in the northern and southern hemispheres. This simulation suggests that early land plants likely thrived in humid coastal areas, and that wind did not play a significant role in spreading spores between different continents. The results of the simulation match well with what we know from studying rocks and fossils from that time period.