Forests are transitioning from carbon sinks to carbon sources, warns new study

Forests are one of the largest carbon sinks, they produce oxygen and also regulate the rainfall regime. But a paradox is occurring: from sinks, they are turning into carbon sources, making it more difficult to slow global warming

Nothing is left to the imagination as far as deforestation and climate change are concerned, since it is a fact that, on the whole, forests are the second most important carbon reservoir after oceans. Forests carry more than 860 billion tons of carbon and absorb approximately a third of human-caused CO2 emissions every year, preventing this carbon from building up in the atmosphere.

Contrary to this, a new study by the UK Met Office shows that wildfires are accelerating carbon losses from ecosystems. This shift reduces the ability of forests and the planet to sequester carbon, further complicating efforts to meet global climate goals.

The shift means forests around the world will turn from carbon sinks into carbon emitters, and it will be much harder to slow down global warming.

With warming at 2.34°F, we’re already seeing fire impacts on carbon storage in ecosystems,” says lead author Chantelle Burton. “This makes the Paris Agreement’s target of 2.7°F all the more important to limit escalating impacts.”

This accelerating trend may already have passed a “critical temperature threshold” beyond which fires trigger significant changes in tree cover and carbon storage, the study said.

The worrying thing is that the current highest temperature at which these effects are pronounced globally is 2.41°F above levels within the pre-industrial era, which is already almost close to the current warming levels.

The study

The research used advanced global climate and land models to understand better how fires affect the carbon storage capability of ecosystems. These models simulate plant growth competing for resources, responding to environmental changes, including all essential nutrients, and how their climate-altered availability affects fire behavior. Analyzing both historical data and future scenarios, the team identified critical temperature thresholds beyond which fires significantly alter tree cover and carbon storage. Indeed, strikingly, the last temperature at which such impacts become widespread is a rise of 2.41°F-which is near current levels of warming.

“Our findings underscore a harsh reality: fires are not just a problem of the future,” says coauthor Douglas Kelley. “They are affecting our planet now. As temperatures rise, fires are increasingly shifting natural carbon sinks towards carbon sources.”

What’s more, though some areas may be nearing the threshold, the study suggests that in parts of the world large-scale losses due to fire might not be realized until warming hits 3.6°F.

What’s needed?

In the meantime, there is an imperative to include fire consequences in climate planning and update strategies. It’s time again for world leaders to take drastic action.

And why not? In view of upcoming COP climate negotiations, these findings could provide further solid ammunition for leaders to take strong measures in order to tackle the climate crisis.