Now researchers in the US reckon they have the definitive answer. By using the latest modelling techniques and taking into account all the important uncertainties, Xiang Gao and her colleagues from Massachusetts Institute of Technology, the University of Alaska, Purdue University and the Marine Biology Laboratory have concluded that the climate impact of this increase in atmospheric methane will be small, particularly when weighed against human emissions.

"We used the MIT Integrated Global System Model (IGSM), which quantifies various sources of uncertainty in climate projections," Gao told environmentalresearchweb. "This is the first time a model like this has been used for this application."

The model accounts systematically for key sources of uncertainty stemming from human emission pathways, global climate sensitivity and regional shifts in climate change.

Gao and her colleagues found that the additional warming due to degradation of Arctic permafrost would be no greater than 0.1° C by 2100. What's more, for this temperature feedback to be doubled would need at least a 25-fold increase in methane emissions. Overall, this biogeochemical global climate-warming feedback is relatively small whether or not humans choose to constrain global emissions, they conclude.

"While we are confident in our findings, we also recognise that these Arctic ecosystems remain insufficiently observed, and there are still gaps in our knowledge of this subject, such as the biogeochemical mechanism and the hydrologic response," said Gao. "We want to extend this study in the future to examine climate feedback in a more comprehensive framework and also look at other greenhouse gases."

The team published the study in Environmental Research Letters (ERL).

Related links

Related stories