In a study published in the prestigious academic journal Proceedings of the National Academy of Sciences of the United States of America (PNAS), scientists from the University of Granada and the University of Wyoming have demonstrated that a temperature increase of just 0.5° during the Medieval Warm Period (between 800-1300 AD) led to a significant rise in the frequency of wildfires in the Rocky Mountains in the US and the amount of area burned. According to their research findings, 83% of the trees in the region were set ablaze during these wildfires.

The researchers have been able to study how the frequency of wildfires varied so considerably in the past by examining lake-sediment charcoal records spanning over 2,000 years. They then used this data to reconstruct the history of wildfires throughout a representative subalpine forest landscape in Colorado (US) over a period of two millennia.

Gonzalo Jiménez-Moreno, from the UGR´s Department of Stratigraphy and Palaeontology and one of the authors of the work, explains: “When a wildfire occurs, a great deal of charcoal is produced. The charcoal is released, in the form of ash, via the smoke clouds which billow up into the earth´s atmosphere. These particles then fall back down to the earth´s surface and are deposited in the sedimentary basins within a radius of a few kilometres around the wildfire focal point. When we study the amount of charcoal per cm3 of sediment, we can ascertain that wildfires were prevalent during certain periods of history, while they were not so commonplace during others.”

Jiménez-Moreno adds: “In this article we have proved that the frequency of wildfires increases when temperatures increase, something which occurred during the Medieval Warm Period and which is also occurring at present.”

The results indicate that the increases being observed in current temperatures are set to cause more and more wildfires in the forests of the Rocky Mountain region. However, Jiménez-Moreno points out: “This will also apply to other regions of the world such as our own [Spain and Europe]. Although the study was conducted in the Rocky Mountains, the results can be extrapolated perfectly to other regions on our planet, such as Europe, given that over the past number of decades we´ve been experiencing notable temperature increases, similar to those that caused the great wildfires in the Medieval Warm Period. These rising temperatures will result in more and more serious outbreaks of wildfires in the US, Europe and other regions.”

Bibliography:

Medieval warming initiated exceptionally large wildfire outbreaks in the Rocky Mountains, W. John Caldera, Dusty Parker, Cody J. Stopka , Gonzalo Jiménez-Moreno , and Bryan N. Shuma. PNAS, Article #201500796

Contact the research group:

Gonzalo Jiménez-Moreno

Department of Stratigraphy and Palaeontology, Faculty of Sciences, UGR

Email: gonzaloj@ugr.es

Phone: + 34 958248727