Volcanic eruptions can abruptly influence the climate. During a large eruption, sulfur dioxide (SO2) is expelled into the stratosphere, where it could stay for years and gradually get oxidized into sulfate aerosols. Being highly reflective, sulfate aerosols reduce the incident sunlight and cool the Earth's surface. By drilling into glaciers and ice sheets, scientists can access the archives of the history of atmospheric composition. A team of multidisciplinary researchers led by Joseph McConnell of the Desert Research Institute in Reno, Nevada deduced that a volcanic eruption occurred in 43 B.C., a year after the assassination of Julius Caesar in the Ides of March (March 15) in 44 B.C, which left a power vacuum and led to bloody civil wars. According to historical accounts, this was also a period of poor weather, crop failure, widespread famine, and disease. Analyses of tree rings and cave stalagmites from different parts of the globe provided complementary data. The Northern Hemisphere got drier while the Southern Hemisphere became wetter. Indeed, Greek historian Appian recorded that there was a lack of flooding in Egypt, which also faced famine and pestilence. Rome's interest in Egypt as a source of food intensified, while the aforementioned problems and civil unrest weakened Egypt's ability to resist. It came under Roman rule after Cleopatra's suicide in 30 B.C. While it is difficult to say for certain whether Egypt becoming a Roman province would have happened if Okmok volcano (in modern-day Alaska) had not erupted, the eruption likely hastened the process.