'Killer Trees' threaten planet Earth

abc [au]: Scientists question trees' role in global warming

Under the United Nations' Kyoto Protocol on global warming, the forest is a saint, as trees suck in carbon dioxide (CO2) as part of the natural process of respiration.

By such thinking, if Kyoto signatories plant lots of forests, they create wonderful sponges that absorb the dangerous climate-altering gas.

But what if trees, in addition to taking in CO2, also emit a greenhouse gas of their own?

That scenario is sketched in a new study by European scientists, which if confirmed, would be one of the biggest upheavals in climate science for years.

It would also inflict a serious blow to Kyoto, one of whose key pillars is the faith in "sinks", as forests are called in the treaty's jargon.

Until now, the mainstream belief is that atmospheric methane chiefly comes from bugs: from bacteria working in wet, oxygen-less conditions, such as swamps and rice paddies.

But in a study published in the journal Nature, a team led by Frank Keppler of the Max Planck Institute in Germany has found living plants, dried leaves and grass emit methane in the presence of air.

Nor is this gas just a piffling amount. Read more