A map is a mark of our lives in time, a journey transcribed. And it was a map, in part, that drew me to Australia, to better understand what fire maps can mean in our climate-change era, and to learn how a robust commitment to geospatial knowledge can help us manage what may be our most hazardous and valuable resource — the carbon that’s either released or sequestered in every fire-affected forest, bush, savanna and grassland.
My own journey, by jet, train, bus, Land Cruiser and helicopter, burned a carbon debt I’ll work most of my career to pay back. In the fall of 2012 I flew some 14 hours across the Pacific Ocean from the United States to Australia, then four hours from Sydney to Perth. After the Australian Fire Authorities (AFAC) and Bushfire CRC meeting, I flew north to Broome, the west coast gateway to mining, tourism, and the aboriginally managed lands. From Broome, I was driven northeast via Land Cruiser by Philip De Bruyn, the fire planning coordinator for the Kimberley Ranger Program. We bounced through red dirt and the squat gum forest, past wallabies and cattle and free-roaming fires and into the sandstone and red-rimrock country of the Kimberley, one of the more remote parts of a continent that gave us the type specimen for “outback.”
I had other reasons to travel this far, but this particular leg of a larger journey was inspired by a map I’d first seen in a talk at a fire conference in South Africa; it conveyed information on the North Australian Fire Information (NAFI) website and network. I needed to witness firsthand what anyone with a computer and slow Internet connection can observe from afar: that the Australian bush burns every few years (even every year), and it burns wide and far across the land.
The NAFI maps were telling the diurnal and seasonal story of man and fire across a big land. This was the smell of smoke to a smoke-chaser. To know fire you must know Australia, and NAFI seemed the tool to guide us to where cutting-edge science meets our original fire-stick tool.
It’s a familiar story: the bush has burned across the epochs of evolution and fire adaptation that predates human timekeeping — the first people here walked with fire sticks, and before them (and today) the pre-monsoon lightning ignited the landscape. Now, as the fires burn, we can watch the heat signature progress in near real-time, thanks to satellites and the calibration and mapping work of the fire researchers and practitioners I was joining in the bush.
The carbon burns and out-gasses into the sky. Yet if we manage the fires, return to less frequent and patchier cool-season burns that steal the fuel from hot late-season burns, we can conserve the carbon in the soil and roots, in regenerating bush and resilient trees. This is what we know to do and are doing, thanks, in part, to teams of researchers and practitioners like those I’m traveling with, who ensure that tools like NAFI pull the satellite data down in order to serve the needs that grow from the ground.
The burning bush
After the day’s drive, we meet with the rest of the team members to camp at a wet billabong near Karunjie. They’ve come from the opposite side of the outback, a day-and-a-half ’s drive from Darwin at the north-central top of the continent.Andrew Edwards, a research fellow with Bushfire NT and the Darwin Centre for Bushfire Research at Charles Darwin University, had invited me here after we’d chatted at AFAC. He shakes my hand and asks, “So Ron, what’s your question? Why are you here?” My question? De Bruyn, with whom I’d chatted for hours, suggests my deeper motive: “To have a good walkabout in the Kimberley?”
To which I agreed, though I did offer a purpose — to see, first-hand, how the science and practice are coming together — to see how fire science, applied fire and carbon management can support each other as we face the challenge of climate change. And to see it on the ground, to better apply these lessons elsewhere.
For the next few days and later, in Darwin and by Skype, Edwards and colleagues, including Peter Jacklyn, the NAFI web architect, explain the details of the science and resulting scheme (which is a word, outside the U.S., that lacks our illicit sense of underhandedness). When early cool-season burns dominate, the burns are patchier; less litter is consumed, and less of the grass and bush biomass, so that the grasses re-sprout and scorched eucalyptus starts to bud and leaf out before the dry season stunts the growth, thus drawing carbon from the atmosphere into the biomass. This compares to a late-season burn, which out-gasses more carbon and begins, over time, to convert the resilient bush into over-dominant exotics, which are, in turn, more flammable, and the carbon sink degrades.
To reach the point where NAFI can support a carbon scheme, three key questions had to be answered, by fuel model and habitat type, and by early and late burns:
- The CO2 emissions released
- The emissions conserved
- The emissions sequestered
The potential for carbon sequestration in the tropical savanna is based on definitive research by Jeremy Russell-Smith, Peter Cooke and others that concluded that the carbon sequestration can occur in fire-managed savanna that receives more than 1,000 mm precipitation a year, as does the northern tier of Australia.
The tropical savanna covers some 12% of the globe and is one of our richest sources of carbon sinks and biodiversity. This week, though, we were seeking to expand the original premise: can lower rainfall sites, from 600-1,000 mm, also sequester carbon, if we burned smarter.
So it was time for the research teams to re-measure old burns and to light new hot-season burns. For this scheme to work, you need 10 years of prior baseline burn data, plus this sort of field and satellite work to determine fuel accumulations. Finally, you can start to measure each year’s savings, by comparing a year in which you’re managing fire (for carbon and biodiversity and cultural values) against the earlier years. You need horizontal burn patchiness and vertical impact of scorch height. You need to sample from soil to grass/herbs to shrubs and trees, from fine to course fuels. And you need to confirm this on foot and by helicopter to correlate it to the satellite data, all of which feeds the NAFI maps.
The process is based on tallying “Burning Efficiency,” a formula that multiplies “Patchiness” by “Combustion Completeness” to calculate your greenhouse gas emissions. Building on decades of work, the team has determined that fire seasonality can become a proxy for and key mechanism that, when combined with Moderate Resolution Imaging Spectroradiometer (MODIS) data, can yield a robust and real-time tool for fire severity mapping. Edwards et al are working on a model for a Normalized Burn Ratio (combining seasonality with MODIS and other tools) that’s nearing 94% accuracy for mapping severity, compared with 50%-60% accuracy with MODIS alone. The result is that you can press a few buttons on a NAFI map to generate a seasonal and annual burn report, which can help you interpret the key impact of burn seasonality: that early season burns have from 10%20% more patchiness and 10% less combustion than late-season burns — which equals carbon sequestered.
This process, intuitive as it is complex, is why I found myself helping to ignite research burns in the Kimberley in early September, the start of hot season burns. The team was seeking to fill the data gaps, to measure what burns and what remains, to compare with the earlier cool-season burns and measure the comparative impacts on both biodiversity and carbon sequestration. This is a form of valuation, as key to climate’s health as depositing a paycheck in a bank machine.
De Bruyn drags the torch for these burns and I’m running ahead to scout a good line. We turn the corner and De Bruyn’s drip torch hooks the head of the fire and we both stop, breathing equally hard. Then we turn to the fire to take photos of the flames, which crackle with an occasional internal whoomp as the ground fuels ignite a tree’s canopy. We catch our breath and then take fire back to the gravel road where we started. Most of the burn’s intensity has cooled within 10 minutes. The grasses and forbs and the lower leaves of the trees are burnt to nothing. The upper leaves are singed but alive, and in a week, the basal roots and stems will be flushing green.
A small finger of fire burns in 5-foot flames across the road. In the interior, the flames have crossed our burn line. I ask, “Should we put this out?” No, I’m told, this fire will burn out in the evening’s humidity or when the fires reach an area that’s been previously burnt out. And we think it does, which we can confirm, by satellite, via a low-bandwidth NAFI download via a sat-phone. Two days later, on a helicopter flight to map burn severity to the southeast, we do see a column suspiciously near our research burn; but as we fly, we determine that it’s further west than our fire.
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