Will global warming cause fires in the Arctic tundra?

Research into sediment cores in the Arctic seems to indicate that an increasingly warm climate could make the Arctic tundra far more likely to catch fire. Findings of scientific studies have been published in a well-respected online journal PLoS ONE.

Philip Higuera from Montana State University led the study over period of four years that examined sediment samples taken from 4 lakes in Alaska in an effort to determine the types of vegetation that existed immediately after the last ice age.

They examined pollen grains found in samples and discovered that after the ice age. The tundra in the region was of a totally different nature than it is today. At that time, it was covered in tall birch bushes whereas today the tundra is made up of herbs and grasses.

They also discovered charcoal in the samples, which indicated that there had been large continuous fires in the tundra wastelands. Higuera stated “Modern tundra burns so infrequently that we don’t really have a good idea of how often tundra can burn. Best estimates for the most flammable tundra regions are that it burns once every 250-plus years.”

This research is deemed to be important because. When combined with other evidence the indication is that with increased temperatures in the Arctic over the last hundred years. The same shrubs are beginning to spread quickly across the vast tundra landscape.

“There is evidence of increasing shrub biomass in modern tundra ecosystems, and we expect temperatures to continue to increase and overall moisture levels to decrease. Combine these two factors and it suggests a greater potential for fires,” Higuera said. “The sediment cores indicate that it’s happened before.”

These tundra regions account for approximately 30% of the world’s soil carbon. The permafrost that covers the region currently locks in this carbon. However, as warming of the earth continues this could easily cause is permafrost melt away. Thus releasing huge amounts of carbon into the atmosphere, causing increased global warming, which in turn would melt more permafrost releasing more gases into the atmosphere.

“Vegetation change through an increase in shrub biomass and more frequent burning will change a great deal of the carbon cycle in these high latitudes,” Higuera said. “We don’t fully understand the implications, except that it’s reasonable to expect that carbon that was previously locked up could enter the atmosphere.”

The scientific paper is only the first Higuera expecting to publish in a series about his findings over the four-year period.