Fires in Iceland: human interference even 1,100 years ago

For the first time, the analysis of an ice core taken from the east coast of Greenland, in Renland, has allowed researchers to recreate the trend of the fires that have scourged the Icelandic forests over the last five thousand years.

The discovery was made by an international team led by Ca’ Foscari University of Venice and the Institute of Polar Sciences of the National Research Council of Italy (CNR-ISP). The results, which were published in the journal Climate of the Past, are a crucial contribution to the understanding of the links between fires, climate and human action.

Ice has always been the backbone of the climatic and environmental history of our planet and it allows tracing back information from past centuries and millennia about temperatures, volcanic eruptions and even fires.

“The analysis of the chemical compounds found in ice cores collected in polar areas helps to recreate climate-related aspects and weather events of the past'', confirms Andrea Spolaor, researcher at the CNR-ISP. “In this case we are talking about compounds such as black carbon, ammonium and levoglucosan, produced during biomass burning. By measuring these tracers, we found that in the high North Atlantic, which encompasses the north-east, south-east and south-west coasts of Greenland and Iceland, more than 4,500 years ago the number of fires decreased thanks to weaker summer insolation, resulting in the expansion of glaciers and and sparser vegetation”.

The researchers examined the Recap ice core (Renland ice cap) at Ca’ Foscari University of Venice, the CNR Institute of Polar Sciences and the Centre for Ice and Climate in Copenhagen.

“The climate factors that most affect fires are temperatures, summer insolation, rainfall and humidity, along with quantity and type of vegetation”, Delia Segato, researcher from Ca’ Foscari University of Venice, explains. “In the presence of dense vegetation, fires typically last longer due to greater availability of flammable material”.

In addition to the climatic factors, the study also revealed that another reason why more than 1,100 years ago the number of fires decreased in the North Atlantic was due to human interference.

The researchers explain that “The decrease recorded in this period is due to the loss of vegetation in the Icelandic area”. “The Viking colonisation of Iceland caused one of the first environmental disasters in history and even today, after a millennium, the Icelandic forests have not fully recovered. The Vikings deforested extensively, causing the loss of more than 25% of vegetation in less than a century. The settlers, following the customs of their native lands, used to cut down birch tree forests to collect wood and to remove the shrubs to open grazing lands”.

The human impact in the high North Atlantic continued over the centuries. The researchers conclude by stating that “In the two most recent centuries, we have found that fires have increased due to climate change and emissions caused by human activity''.

“The results of the study show that regions at extreme latitudes represent one of the first places on Earth where climate change is having the most catastrophic effects. At the end of summer 2020 alone, fires in the Arctic Circle caused the emission of 244 megatons of CO2, exceeding by 35% those recorded in 2019. In these areas it is therefore essential to improve the understanding of climate trends and the history of fires”.