Tree farms won't halt climate
The New Scientist, Oct. 28, 2002
Planting trees to soak up carbon dioxide actually releases a surge of the greenhouse gas, suggesting the Kyoto Protocol is based on false science
The Kyoto Protocol to halt climate change is based on a scientific fallacy, according to the first results of CarboEurope, a Europe-wide programme that has pioneered research into the carbon budget.
The protocol says that countries can help meet
their targets for cutting emissions of greenhouse gases over the next decade by
planting forests to soak up carbon dioxide. But the soil in these "Kyoto
forests" will actually release more carbon than the growing trees absorb in the
first 10 years, the new research shows.
"Countries will be able to claim carbon credits for the forests. But that won't reflect what is happening in the atmosphere," says Riccardo Valentini of the University of Tuscia in Viterbo, Italy. He presented the CarboEurope data last week in Valencia, Spain.
The project's revelations could embarrass governments now meeting in New Delhi to discuss implementation of the Kyoto Protocol. Earlier in October, Italy announced plans to achieve between 10 and 40 per cent of its emission reductions target for 2012 through forest planting. But now its own scientists are warning that these sinks might not work.
The problem is soils. Forest soils and the organic matter buried in them typically contain three to four times as much carbon as the vegetation above. CarboEurope's researchers have discovered that when ground is cleared for forest planting, rotting organic matter in the soil releases a surge of CO2 into the air.
This release will exceed the CO2 absorbed by growing trees for at least the first 10 years, they say. Only later will the uptake of carbon by the trees begin to offset the losses from soils. In fact, says CarboEurope chairman Han Dolman of the Free University Amsterdam, some new forests planted on wet, peaty soils will never absorb as much carbon as they spit out.
The world's densest network of CO2 monitoring devices has revealed that Europe's forests are absorbing up to 400 million tonnes a year, or 30 per cent of the continent's emissions.
Researchers once assumed that most of this came from young forests, since old forests were thought to be in equilibrium with the atmosphere - sucking up as much gas as they spew out. But, says Valentini, old forests actually accumulate more carbon than young plantations. This suggests that conservation of old forests is a better policy for tackling global warming than planting new ones.
But the Kyoto Protocol takes none of this into account. "Besides ignoring soils, it has no measures to stop deforestation," says Valentini. Instead, it seems to give countries a perverse incentive to chop down existing natural forests and replace them with plantations.
"They will be able to claim carbon credits for the new planting, while in reality releasing huge amounts of CO2 into the air," says Valentini. "There is nothing in the protocol to stop this."
"If the politicians had known in 1997 what we know now, they would never have agreed to its rules on carbon sinks - at least, I hope they wouldn't," says Dolman.