Climate change poses a "major risk" to forests all over the world, threatening widespread tree deaths that could wipe out wildlife, exacerbate global warming and hurt the economy, a major new UN report will warn today.
According to a leaked final draft of the latest UN Intergovernmental Panel on Climate Change (IPCC) report, "tree mortality and associated forest dieback will become apparent in many regions sooner than previously anticipated".
"Forest dieback is a major environmental risk with potentially large impacts on climate, biodiversity, wood production, water quality, amenity and economic activity," says the draft report, seen by The Independent on Sunday.
The dieback will be triggered by the increase in severe droughts, heatwaves, wildfires, storms and pest outbreaks that are expected to result from global warming, it says.
The impact will be felt in forests around the world. "Recent indications are that the temperate forests are beginning to show signs of climate stress, including a reversal of tree growth enhancement in some regions [including Europe], increasing tree mortality and changes in fire regimes, insect outbreaks and pathogen attacks."
Forests store huge amounts of carbon dioxide, and widespread tree deaths threaten to accelerate climate change because dead trees not only release their carbon into the atmosphere but are also no longer able to absorb new CO2.
Experts say climate change poses risks to British woodland. Dr James Morison, of the Forestry Commission's Forest Research unit, said: "The climate is changing and we need to be planning around that. If we don't do anything the problems created by drier summers and droughts could be severe."
He recommends increasing the number of trees planted and broadening the variety grown by importing new species – and existing ones with different provenances.
It is important to mix them up because it is difficult to predict exactly how different species will be hit by climate change, he said.
The threat posed by climate change comes on top of a growth in deadly pests and tree diseases amid growing international plant and animal trading and rising imports of "harmful non-native species", Dr Morison added.
Dr Keith Kirby, at Oxford University's Department of Plant Science, said: "There has probably been a slight rise in general drought deaths over the last 40 years – although data has not been collected on this.
We also have to be more alert to the possibility of forest fires being a serious threat to woodland." He believes forests in southern England could come to resemble a "more Mediterranean structure, with more open and scrubby woodland" as trees compete for dwindling soil-water supplies.
Overseas, the impact on forests could wipe out the valuable habitat of species such as tigers, snow leopards, chimpanzees, gorillas and orang-utans. The threat to woodland is part of a much broader threat posed to the world by climate change, the IPCC report will say.
- The Independent