smouldering wildfires in the UK could be a contributor to climate change, say Scottish researchers.

One Highland blaze that smouldered for weeks released back into the atmosphere a significant amount of the total carbon dioxide it would take all the peatlands across the UK a year to remove.

A team from Glasgow University examined land in the Cairngorms National Park that had a peat fire that lasted for longer than a month in 2006. The smouldering fire covered more than 10 acres.

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The flames ignited layers of peat that continued to burn as a sub-surface smouldering wildfire, after the initial surface blaze and despite several heavy rainfalls.

Such wildfires kill all vegetation and effectively sterilise the area. Scientists say they can have an environmental impact that lasts decades, if not centuries.

Other studies have calculated peat soils cover more than a fifth of Scotland's land area, with the deepest peat storing anything up to three billion tonnes of carbon, or 10 times the amount stored in the whole of the UK's trees. Peat soils in Scotland could contain almost 25 times as much carbon as all other plant life in the UK.

So peat fires, such as the one in the Glasgow University study, can release significant amounts of stored carbon.

Based on the researchers' measurements, they calculated that, in total, the smouldering wildfire near Aviemore burnt between 0.1% and 0.3% of the estimated total amount of carbon sequestered annually by UK peatlands. This indicated that even small events of this nature can release significant quantities of carbon.

The Glasgow team say many countries have promised to reduce carbon emissions by 2050. However, current emission estimates, for example in the UK, do not take into account those from peatlands.

"Direct estimates of the loss of carbon due to smouldering wildfires are needed to inform global estimates of the effect of wildfire on carbon dynamics and to aid with national emissions accounting," the team says.

The large number of wildfires in spring 2011 also only adds to their increasing concern about potential feedbacks between climate, fire frequency, fire severity and carbon fluxes from peatlands.

Matt Davies, lecturer in environmental stewardship, said: "Smouldering peat fires are difficult to detect due to their low temperature and low heat release and the fact that tree canopies remain intact for months afterwards.

"Our case study is the first of its kind in the UK and shows that even small areas of peat fires can release significant levels of carbon into the atmosphere.

"If similar smouldering fires are under-reported in other temperate, forest and tropical peatland regions then emissions from peatland burning may well be a substantially greater issue than currently assumed."

The team's results also provided circumstantial evidence that afforestation of peatland soils, and associated site preparation, may contribute to an increased risk of peat fires.