Peatlands become fuel for wildfires in a warming climate

The loss of water in northern peatlands will intensify global warming and wildfires, according to new research.

An international team of 59 scientists led by McMaster University investigated how various ecosystems lose water to the atmosphere. 

The researchers found that in response to a warming climate, forests and peatlands regulate water loss in dramatically different ways.

Experts in McMaster’s School of Geography and Earth Sciences, Manuel Helbig and Mike Waddington, analyzed observational data from countries across the boreal biome. 

Most current global climate models assume the biome is all forest, an omission that could seriously compromise their projections, explained Helbig.

“We need to account for the specific behavior of peatlands if we want to understand the boreal climate, precipitation, water availability and the whole carbon cycle. Peatlands are so important for storing carbon, and they are so vulnerable.”

Helbig said that until now, it had not been possible to capture such a comprehensive view of these water-cycle dynamics. With the support of the Global Water Futures Initiative and research partners across the globe, new insights are emerging.

As the climate warms, the drier air can absorb more water, yet forest ecosystems respond to the dry air by retaining more water.  

Trees, shrubs, and grasses are vascular plants that absorb carbon dioxide and release water and oxygen through pores in their leaves. These pores close in warmer and drier weather to conserve water.

Beyond the forest, the rest of the boreal landscape is comprised of peatlands and lakes.

Peatlands are made up of organic matter from decaying plant material, and store massive amounts of water and carbon. As long as they remain saturated, peatlands serve as natural firebreaks between sections of forest. 

Peatland mosses are not vascular plants, which means they do not conserve water in a warming climate and are more prone to drying out. When peat becomes dehydrated, it is transformed from a firebreak into fuel.

Helbig explained that drier peatlands mean bigger, more intense fires that can release vast amounts of carbon into the atmosphere, accelerating global warming.

“It’s crucial to consider the accelerated water loss of peatlands in a warming climate as we project what will happen to the boreal landscape in the next 100 to 200 years,” said Helbig.

The study is published in the journal Nature Climate Change.

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By Chrissy Sexton, Earth.com Staff Writer