12:00 pm
LONDON - Carbon sinks - forests and farmlands that can absorb carbon dioxide - will not be able to soak up environmentally damaging greenhouse gas indefinitely, scientists say.
In a report which could have important implications for New Zealand's stance at world climate change talks in Morocco, a panel of 30 carbon experts warned carbon sinks could not be relied on because their ability to soak up carbon dioxide would change with time.
"Although carbon sinks have a role to play in absorbing excess carbon dioxide, it is possible that the net global terrestrial carbon sink may disappear altogether in the future," Professor David Schimel of the Max Planck Institute for Biochemistry in Germany said in a statement.
New Zealand has been a vocal advocate for forests, and possibly even re-generating indigenous vegetation, to be accepted internationally as a carbon-sink, capable of holding atmospheric carbon as long as the forest is not felled or burned.
Carbon dioxide is one of half a dozen "greenhouse gases" contributing to global warming, and the Kyoto Protocol requires New Zealand to slash its greenhouse gas emissions to 1990 levels.
New Zealand negotiators have argued strongly that it lower its levels by cutting emissions from fossil fuels used in transport and industry, but also by planting trees to absorb carbon dioxide.
New Zealand is expected to have to remove the equivalent of 363 million tonnes of carbon in the first Kyoto "commitment period" from 2008-2012, and is looking to its "Kyoto forests" - trees planted since 1990 - to remove 100 million tonnes of that.
Details of how sinks are to be included in the Kyoto Protocol are still being negotiated but to be effective, the system would need to penalise people who cut down forests of any age, without re-planting, as well as rewarding people who planted new forests after 1990.
New Zealand had high forestry planting rates from 1992-2000, in which 520,000ha of new forest were established - but most of that has been by farm foresters or small investors.
The nation's bigger corporate foresters have claimed their $3.6 billion export sector will be gutted if the Government presses ahead with plans to accept only the so-called "Kyoto forests" to qualify as carbon sinks.
A ministerial steering group on climate change, convened by Energy Minister Pete Hodgson - who is attending the Moroccan meeting - released in June proposals for using New Zealand forests as a "carbon sink" for long term storage of carbon from the nation's carbon dioxide emissions.
But Will Steffen, the executive director of the International Geosphere-Biosphere Programme (IGBP) and a co-author of the report just published in the science journal Nature, said it gave a comprehensive picture of carbon sinks on land and their impact on global warming.
"It is a major step forward in understanding where terrestrial carbon sinks actually are, why they are there, and how long they will operate in the future," he said.
Scientists have warned that if measures are not taken to reduce global warming, disastrous climate changes including droughts and flooding will occur.
Carbon sinks and emissions trading, essentially a market for buying and selling the right to pollute, were the main stumbling blocks of the failed UN conference on climate change in The Hague last year. The United States has withdrawn from the talks.
The aim of the Morocco meeting is to bring into force the 1997 Kyoto Protocol, which commits industrialised nations to cut their greenhouse gas emissions by an average of five percent of 1990 levels by 2012.
According to the report, carbon sinks are created by changes in land use, reforestation and improvements in forest management. But when a forest matures, the sink becomes less effective.
One of the issues that must be resolved at the talks is whether Russia should be allowed to make greater use of its carbon-storing forests to set against its emissions target than was agreed a climate talks earlier this year in Bonn.
- REUTERS
Intergovernmental Panel on Climate Change (IPCC)
United Nations Environment Program
World Meteorological Organisation
Framework Convention on Climate Change
Executive summary: Climate change impacts on NZ
IPCC Summary: Climate Change 2001