Wetland dry-up eases methane levels.


A new study has shown that methane levels have stabilised in the atmosphere but it is only because emissions produced by wetlands have fallen.
The study, which has been published in the journal Nature, has shown that while sources of methane from human activities like mining continues to rise, the overall levels in the atmosphere have levelled out.
Dr Paul Steele, from the CSIRO, says the reason is the prolonged drying of wetlands has caused a fall in the amount of methane released from swamps and bogs.
"Had it not been for this reduction in methane emissions from wetlands, atmospheric levels of methane would most likely have continued rising," Dr Steele said.
"They've just offset each other so the net, the total, didn't change."
Methane is said to have been responsible for one-fifth of the enhanced greenhouse effect over the past two centuries.
If the drying trend of wetlands is reversed, Dr Steele says methane levels in the atmosphere may again increase, worsening the problem of climate change.
Scientists say the Earth is getting hotter because of human activities, notably the release into the atmosphere of greenhouses gases which let in sunlight and trap its heat like the walls of a greenhouse.
"Methane is an important greenhouse gas and this work is a major step in better understanding why methane emissions are changing," Professor Neville Nicholls, an expert on climate change at Monash University in Melbourne, said.
"But the relentless increase in carbon dioxide emissions from fossil fuels is, and will continue to be, the most important driver of the global warming we are witnessing."
The scientists used computer simulations to track back to the source of methane emissions and how the gas is transported in the atmosphere.
- ABC/Reuters