Arabic writings from a thousand years ago are helping piece together past climate events and trends, Spanish researchers say.

Researchers in Spain said the writings of scholars, historians and diarists in Iraq during the Islamic Golden Age between 816-1009 are providing evidence of abnormal weather patterns.

The writing of historians and political commentators of the era are mainly concerned with social and religious events of the time but do include mentions of abnormal weather events, the researchers report in the journal Weather.

"Climate information recovered from these ancient sources mainly refers to extreme events which impacted wider society such as droughts and floods," lead author Fernando Dominguez-Castro of the University of Extremadura said. "However, they also document conditions which were rarely experienced in ancient Baghdad such as hailstorms, the freezing of rivers or even cases of snow."

While many ancient documents in Iraq have been lost to a history of invasions and civil strife, researchers said they've rescued some meteorological information from surviving works of writers including al-Tabari, Ibn al-Athir and al-Suyuti.

Researchers said they believe the sources prove Iraq experienced a greater frequency of significant climate events and severe cold weather than it does today.

While the study focused on Iraq, it suggest a potential for reconstructing global climate from an era before meteorological instruments and formal records, they said.