Forests' role as massive carbon sinks is "at risk of being lost entirely", top forestry scientists have warned.The International Union of Forest Research Organizations (IUFRO) says forests are under increasing degrees of stress as a result of climate change.
Forests could release vast amounts of carbon if temperatures rise 2.5C (4.5F) above pre-industrial levels, it adds.
The findings will be presented at the UN Forum on Forests, which begins on Monday in New York.
Compiled by 35 leading forestry scientists, the report provides what is described as the first global assessment of the ability of forests to adapt to climate change.
"The fact remains that the only way to ensure that forests do not suffer unprecedented harm is to achieve large reductions in greenhouse gas emissions"
Professor Andreas Fischlin,