Was the Medieval Warm Period a global event?

Friday, June 21, 2024
By John Mason

The Medieval Warm Period was regional, not global.

Between 950-1250 AD, temperatures as warm as those in the mid-20th century were isolated to parts of the Northern Hemisphere. Most of the planet was relatively cool.

The regional nature of the warming indicates that internal variability — how and where energy is moved about within the system — was the main cause. In addition, this was one of the quietest periods of the past 2000 years for volcanic eruptions. Fewer eruptions meant fewer sun-reflecting particles in the air.

The Medieval Warm Period’s warming was also short-lived. The Little Ice Age started soon after and continued until the Industrial Revolution, when our fossil fuel burning intensified.

All of Earth’s regions are now warming, and average global surface temperatures are about 1°C higher than during the Medieval Warm Period.

Current global warming will continue as long as humans keep emitting heat-trapping gases into the atmosphere.

This fact brief is responsive to conversations such as this one.
Skeptical Science is a non-profit science education organization. Our goal is to remove a roadblock to climate action by building public resilience against climate misinformation. We achieve this by publishing debunking of climate myths as well as providing resources for educators, communicators, scientists, and the general public. Skeptical Science was founded and is led by John Cook, a Senior Research Fellow with the Melbourne Centre for Behaviour Change at the University of Melbourne.