Thursday, February 11, 2016
Tasmania’s Burning Peatlands Caused by global warming?
No. There was no statistically significant terrestrial global warming for over 18 years. And even El Nino pushed the average terrestrial global temperature to a 2015 rise of just over one tenth of a degree Celsius
As the climate warms, the hoary peatlands that blanket Tasmania’s west are drying out, and burning up. The cool moist conditions they rely on are disappearing but the peatlands are exacting a small revenge on the species responsible.
While fires have typically burned across peatlands with little effect, Professor David Bowman said that as they dry, the centuries-old organic soils beneath are starting to smoulder.
In turn, public health experts say the smouldering peatlands are letting off nasty smoke, exacerbating the already serious threats posed by bushfires.
According to Prof. Bowman, there’s little doubt that human-induced climate change is to blame, and the problem will only grow as temperatures rise.
“A lot of people haven’t caught up to how fast climate change is in comparison to the background ecological change,” Prof. Bowman said. “What is happening with a warming climate is ecological change is just speeding up, and there’s going to be collateral.”
“There is damage, and I think these fires are part of that. There have been big fires in the past…but I suspect the trend we’re seeing now, of really big fires, and high frequency big fires, often lit by lightning storms, is signalling something different.”
It’s unclear how bad the damage is at this stage, but if the organic soils under the peatlands combust, they take centuries to regenerate. During that time, peatland ecosystems also becomes more fire-prone, lessening the peat’s chances of regeneration.
Prof. Bowman predicts peat soils will likely be relegated to localised patches along creek lines, and on lower slopes by the end of this century. Outside of these refugia, he expects large tracts of Tasmania’s western wilderness, much of it World Heritage Listed, will be replaced by “scrublands on gravelly ridges”.
“I actually think at a broader scale – if you believe the climate models, and data – it’s pretty simple analysis,” Prof. Bowman said.
“That is, that peatlands require a certain climate; the Tasmanian peatlands are right on the margin; and if you warm the world, the peatlands that exist in Tasmania will … be replaced by a different sort of bush that will be more flammable and has a different sort of hydrology.”
And out of the ashes of Tasmania’s peatlands, a new threat is rising.
“The odd bushfire, you know, every so often, is typical basically anywhere in Australia,” said Dr Fay Johnston, a Menzies Institute researcher at the University of Tasmania. “But here we’ve got vegetation and soil burning that doesn’t normally burn. It’s more than just smoke from a passing vegetation fire, and that can be bad enough.”
“The mixture is more toxic, particularly if you’re close to it, and the sheer load of particles, because it’s incomplete [and]inefficient combustion, is much greater,” Dr Johnston said.
“The smoke mixture has a higher load of toxic ingredients, including suspended particles and products of incomplete combustion – hydrocarbons, volatile organic acids, a whole suite of things – that in their own right are highly irritating.”
“With peat fires, you tend to have a bigger exposure and you tend to have an exposure that goes on for longer,” she said.
On Friday, when authorities issued their latest stakeholder update, there were still over 70 fires – 30 of them uncontrolled – still burning across Tasmania. Smoke has reached as far as Melbourne, and Dr Johnston said that it’s likely around half of Tasmania has been exposed to the damaging haze.
“Everybody in Tasmania, more or less, would’ve got some smoke, but it was the people who live up in the north west who really got affected. It was quite bad for a good week, and it’s fluctuating on and off in some cases since then,” she said.