Ash dieback is triple whammy for net zero plans
20.08.2025

• Study reveals carbon losses from soils due to tree disease in Britain for first time
• Deaths of millions of trees will have multiple negative impacts on climate change mitigation

Ash dieback and other tree diseases are resulting in significantly more greenhouse gas emissions than previously thought because a large amount of carbon is escaping from woodland soils, a study has found. This is in addition to carbon losses from tens of millions of dying trees and reduced removal of CO2 from the atmosphere due to the widespread deaths of mature ash trees.

The research team led by the UK Centre for Ecology & Hydrology (UKCEH) says that the exponential rise in tree diseases across the world are likely to hamper forests’ ability to help meet net zero plans.

They estimate losses from soils alone due to ash dieback in British woodlands resulted in 5.8 million tonnes of CO2 emissions over five years (2016-21). This is equivalent to over half the amount of CO2 removed from the atmosphere by broadleaf woodlands in Great Britain in a year, or alternatively the total amount of CO2 emitted by cars travelling on Scotland’s roads annually.

While the loss of carbon from diseased trees themselves and reduced removal of CO2 has been previously noted by scientists, the authors of the latest study say a third impact – the effects on carbon cycling and storage in the surrounding environment – has not been considered before.

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