A soon to be revealed global map for road building could show planners how to help rather than harm the environment.
The damage that building roads has on the landscape is well documented. From deforestation and the unwanted spread of exotic species, to territory fragmentation and chemical changes in the local environment, the ecological effects are devastating.
Conservationists have logged the reluctance of species, from mountain lions to land snails, to cross roads. Meanwhile road-kill numbers of bolder mammals including Alaskan Caribou and the endangered Tasmanian Devil have soared.
Australian Laureate and professor of tropical biology at James Cook University of Cairns, Professor William Laurance is just one of a growing body of researchers anxiously watching the proliferation of roads across the planet.
"You feel like you're the little Dutch boy plugging your fingers in the dyke but it just keeps springing more and more leaks," he says. "We've been trying to fight this one road at a time and it's just a losing prospect."
Prof Laurance has devoted much of his academic career to researching the environmental impacts of roads. His seminal paper published in Science more than a decade ago shocked nations worldwide by highlighting how the Brazilian Amazon was losing some two million hectares of forest a year, the fastest rate of deforestation in the world.
Prof Laurance linked the mass destruction of the Amazon to road building, intended to accelerate development in agriculture, timber and mining. These planned roads also generated vast networks of secondary and tertiary roads for industrial-scale, but illegal, logging and mining, with dire consequences.
"Up to 95 per cent of deforestation will be within 10km of a road while illegal hunting and mining have been big issues," Prof Laurance says. "The ultimate cause [of environmental damage] is population growth and economic development, but roads are very, very associated. If we could pick one thing to limit, even more than climate change, it would be to constrain road expansion, especially in frontier regions."
When he unveiled his Amazonian findings, Prof Laurance suggested using agricultural land intensively rather than extensively to stem 'rampant exploitation'. But today, road networks are still spreading across the Amazon as well as the Congo region, Borneo, Siberia and Namibia.
Global map of road building
Earlier this year Prof Laurance joined forces with professor of conservation science at the University of Cambridge, Professor Andrew Balmford, to publicise a solution. Writing in Nature, the pair outlined plans for a global map for road building that they believe would keep roads out of natural areas and help protect crucial ecosystems.
Crucially, their map could also help to reduce the conversion of intact habitat to food crop, biofuel and livestock production. Today, vast funds are poured into agriculture research to boost crop yields, but both Prof Laurance and Prof Balmford are convinced these efforts will only lessen the impact of farming on ecosystems if coupled with strategic road development. Their map could provide the guiding principles.
"Latest UN figures project the world population to increase to nearly 11 billion people so we can't just sit around in ivory towers saying, well, we can't have new roads," says Prof Laurance. "We have to have development, so let's make it smarter development. Our idea is to identify areas where new road or road improvements could really yield a lot of economic developments... and constrain road expansion in frontier regions."
So what exactly will a global map for road building look like? Still under development, the researchers are considering a Google Earth-style platform in which the user can zoom into a region to glean detail, but then zoom out to get the bigger picture.
"Ideally you want it scale-free so you can zoom in or zoom out at any scale," explains Prof Laurance. "So if you are in the Democratic Republic of Congo, you'd want to pull down the layer for your country and then zoom in and out again."
As Prof Balmford highlights, a range of scale is imperative to the success of such a map. "There will be a nested series of scales... and the map would show clear areas where road building is extremely risky but other areas where it potentially brings benefits," he says. "It could be useful to organisations that invest large sums of money in road-building projects, such as the World Bank."
Prof Laurance also reckons the map will be colour-coded. Regions in red could represent areas where new roads would inflict greatest damage, whereas green regions would benefit from development.
"Conceptually it's fairly simple," he says. "You'd have a whole spectrum of colours, probably with red and green at either end, representing regions where you'd likely get the least and most benefits. But the devil is in the detail. Getting all the right data at the right spatial resolution is a challenge."
For starters, the map will comprise a myriad of data layers covering the topography of a terrain, habitat cover, levels of carbon stored in a region, soil fertility, climate variables and more. Alongside environmental data, information on, for instance, spatial population distributions and projected urban population growth, will be integrated to represent the human needs or demands of a region.
"We come up with all these factors but at some point you have to say, 'I think this is a really important factor that needs that weighting, while this factor needs a different weighting'," explains Prof Laurance. "We can put this in a framework and decide how different variables are weighted... or we can build this so the person doing the planning puts the weights in."
Planning the map
Following years of research, the researchers broadly know how road development would best take place. More suitable locations would include regions where habitat loss has already taken place and prospects for social and economic development are high.
"We know regions with a lot of projected population growth that also have the right characteristics for agriculture, for example, soils and climate are suitable," says Prof Laurance. "So these areas are going to get weighted towards roading and development."
The researcher also points to regions where little natural habitat is left, but only smallholdings or lower efficiency farming schemes exist. "Again, if this is in an area with substantial projected population growth, you will want to have road improvements and expansion here," he adds.
Regions with so-called yield gaps, where actual agricultural yield does not meet potential yield, could also be prime candidates for development. As with many of the data inputs, the legwork here has already been done. For example, Stanford University researchers have broadly mapped where the yield gaps exist for major food crops, such as wheat in Northern India, rice in the Philippines and maize in Nebraska, US.
But analysis isn't always straightforward In this case, and as Prof Balmford emphasises, a researcher may know where a yield-gap region with unfulfilled agricultural potential is, but can it be enhanced by road improvements? "Sometimes there are other constraints, and this is the scientific challenge," he says.
And as Prof Laurance concedes: "This is part science and part art, but the bottom line is you have to make decisions, so you are explicit about them. This is the approach people use for building these complex spatial models... and at the end of the day, you want something that is intuitive and makes sense to people."
But is the map too little too late? As the researchers get to grips with building the global map, nearly 100,000km of roads have already cut into the Amazon rainforest alone, and this figure is rapidly rising.
For his part, Prof Laurance asserts the map must "come online sooner rather than later", and highlights how road building is relatively amenable to policy modification; it is far easier to cancel or relocate a road project than it is to reduce human overpopulation or halt harmful climate change. And his plans are rooted in realism.
"We don't expect to be this global authority and have economists and planners looking at the map, saying 'Oh no, we can't put a road there'," he says. "But it would be nice if this was part of the conversation. Right now, with a lot of frontier roads, environmental considerations don't even get put on the table."
Prof Balmford also hopes the road map will help inform policy makers where development would be most usefully directed.
"We've now probably lost more than half of all the wild places left on the planet," he says. "We've probably got a generation left before the loss of biodiversity becomes irreparable, so slowing that loss now involves getting a number of very difficult decisions right. This may just be part of that."