The global road-building explosion is shattering nature


Bill Laurance, James Cook University

If you asked a friend to name the worst human threat to nature, what would they say? Global warming? Overhunting? Habitat fragmentation?

A new study suggests it is in fact road-building.

“Road-building” might sound innocuous, like “house maintenance” – or even positive, conjuring images of promoting economic growth. Many of us have been trained to think so.

But an unprecedented spate of road building is happening now, with around 25 million kilometres of new paved roads expected by 2050. And that’s causing many environmental researchers to perceive roads about as positively as a butterfly might see a spider web that’s just fatally trapped it.

A Malayan tapir killed along a road in Peninsular Malaysia.
WWF-Malaysia/Lau Ching Fong

Shattered

The new study, led by Pierre Ibisch at Eberswalde University for Sustainable Development, Germany, ambitiously attempted to map all of the roads and remaining ecosystems across Earth’s entire land surface.

Its headline conclusion is that roads have already sliced and diced Earth’s ecosystems into some 600,000 pieces. More than half of these are less than 1 square kilometre in size. Only 7% of the fragments are more than 100 square km.

Remaining roadless areas across the Earth.
P. Ibisch et al. Science (2016)

That’s not good news. Roads often open a Pandora’s box of ills for wilderness areas, promoting illegal deforestation, fires, mining and hunting.

In the Brazilian Amazon, for instance, our existing research shows that 95% of all forest destruction occurs within 5.5km of roads. The razing of the Amazon and other tropical forests produces more greenhouse gases than all motorised vehicles on Earth.

Animals are being imperilled too, by vehicle roadkill, habitat loss and hunting. In just the past decade, poachers invading the Congo Basin along the expanding network of logging roads have snared or gunned down two-thirds of all forest elephants for their valuable ivory tusks.

Deforestation along roads in the Brazilian Amazon.
Google Earth

Worse than it looks

As alarming as the study by Ibisch and colleagues sounds, it still probably underestimates the problem, because it is likely that the researchers missed half or more of all the roads on the planet.

That might sound incompetent on their part, but in fact keeping track of roads is a nightmarishly difficult task. Particularly in developing nations, illegal roads can appear overnight, and many countries lack the capacity to govern, much less map, their unruly frontier regions.

One might think that satellites and computers can keep track of roads, and that’s partly right. Most roads can be detected from space, if it’s not too cloudy, but it turns out that the maddening variety of road types, habitats, topographies, sun angles and linear features such as canals can fool even the smartest computers, none of which can map roads consistently.

The only solution is to use human eyes to map roads. That’s what Ibisch and his colleagues relied upon – a global crowdsourcing platform known as OpenStreetMap, which uses thousands of volunteers to map Earth’s roads.

Therein lies the problem. As the authors acknowledge, human mappers have worked far more prolifically in some areas than others. For instance, wealthier nations like Switzerland and Australia have quite accurate road maps. But in Indonesia, Peru or Cameroon, great swathes of land have been poorly studied.

A quick look at OpenStreetmap also shows that cities are far better mapped than hinterlands. For instance, in the Brazilian Amazon, my colleagues and I recently found 3km of illegal, unmapped roads for every 1km of legal, mapped road.

A logging truck blazes along a road in Malaysian Borneo.
Rhett Butler/Mongabay

What this implies is that the environmental toll of roads in developing nations – which sustain most of the planet’s critical tropical and subtropical forests – is considerably worse than estimated by the new study.

This is reflected in statistics like this: Earth’s wilderness areas have shrunk by a tenth in just the past two decades, as my colleagues and I reported earlier this year. Lush forests such as the Amazon, Congo Basin and Borneo are shrinking the fastest.

Road rage

The modern road tsunami is both necessary and scary. On one hand, nobody disputes that developing nations in particular need more and better roads. That’s the chief reason that around 90% of all new roads are being built in developing countries.

On the other hand, much of this ongoing road development is poorly planned or chaotic, leading to severe environmental damage.

For instance, the more than 53,000km of “development corridors” being planned or constructed in Africa to access minerals and open up remote lands for farming will have enormous environmental costs, our research suggests.

Orangutans in the wilds of northern Sumatra.
Suprayudi

This year, both the Ibisch study and our research have underscored how muddled the UN Sustainable Development Goals are with respect to vanishing wilderness areas across the planet.

For instance, the loss of roadless wilderness conflicts deeply with goals to combat harmful climate change and biodiversity loss, but could improve our capacity to feed people. These are tough trade-offs.

One way we’ve tried to promote a win-win approach is via a global road-mapping strategy that attempts to tell us where we should and shouldn’t build roads. The idea is to promote roads where we can most improve food production, while restricting them in places that cause environmental calamities.

Part of a global road-mapping strategy. Green areas have high environmental values where roads should be avoided. Red areas are where roads could improve agricultural production. And black areas are ‘conflict zones’ where both environmental values and potential road benefits are high.
W. F. Laurance et al. Nature (2014)

The bottom line is that if we’re smart and plan carefully, we can still increase food production and human equity across much of the world.

But if we don’t quickly change our careless road-building ways, we could end up opening up the world’s last wild places like a flayed fish – and that would be a catastrophe for nature and people too.

The Conversation

Bill Laurance, Distinguished Research Professor and Australian Laureate, James Cook University

This article was originally published on The Conversation. Read the original article.

Climate change played a role in Australia’s hottest October and Tasmania’s big dry in 2015


Pandora Hope, Australian Bureau of Meteorology; Andrew King, University of Melbourne; Guomin Wang, Australian Bureau of Meteorology; Julie Arblaster, Monash University, and Michael Grose, CSIRO

Climate change made some of Australia’s 2015 extreme weather events more likely, according to research published today in the Bulletin of the American Meteorological Society.

As part of an annual review of global weather extremes, these studies focused on October 2015, which was the hottest on record for that month across Australia. It was also the hottest by the biggest margin for any month.

October 2015 was also the driest for that month on record in Tasmania, which contributed to the state’s dry spring and summer, and its bad fire season.

El Niño events usually drive global temperatures higher, and 2015 had one of the strongest on record. So were these records due to El Niño, or climate change? The research shows that while El Niño had some influence on Australia’s weather, it was not the only culprit.

El Niño packed a punch – or did it?

In 2015, a strong El Niño developed, with record high temperatures in the central equatorial Pacific Ocean contributing to 2015 being the hottest year on record globally (although 2016 will smash it). The Indian Ocean was also very warm.

El Niño is often associated with warm and dry conditions across eastern Australia, particularly in spring and summer. The new studies found that for Australia as a whole, while El Niño did make the continent warmer, its direct contribution to record temperatures was small.

Only in the Murray Darling Basin did El Niño make it more likely that the October 2015 heat would be a record. El Niño also played a small but notable role in the dry October in Tasmania.

Temperatures were at a record high across the south of the country.
Bureau of Meteorology

The hottest October

Although record-high spring temperatures might not make you sweat as much as a summer heatwave, ecosystems and agriculture can be susceptible. October 2015 was 2.89℃ warmer than the previous hottest October in 2014, beating the margin set by September 2013, which was 2.75℃ warmer than the previous hottest September.

Even before October 2015 was over, Mitchell Black and David Karoly at the University of Melbourne reported that human-induced climate change played a strong role in the excessive October heat.

The first paper (chapter 23 in the annual review) explains this further. Using the citizen science Weather@home ANZ system, the researchers analysed thousands of simulations of the world’s climate of 2015, generated on home computers (you can donate your computer power here).

To find out whether climate change played a role, some of those simulations included the observed ocean temperatures of 2015, while some included ocean temperatures as if human-caused climate change had never occurred.

According to this method, climate change made breaking the October record four times more likely compared to a world without climate change.

The second paper (chapter 24 in the review) backed this up. This study used the Bureau of Meteorology’s seasonal forecast system to compare the real world to a world with less carbon dioxide in the atmosphere. The researchers came to exactly the same conclusion: rising carbon dioxide levels made a record October four times more likely.

This second study also found that the atmospheric conditions – the series of high and low pressure systems that shift heat from inland Australia towards the south – were more important in driving the extra heat than the extreme global ocean temperatures.

If these weather systems had occurred in a low-CO₂ world, it would still have been an extremely warm month. But for October 2015, climate change increased the temperature by an extra 1 degree.

Driest October for Tasmania

In October 2015, Tasmania received only 21mm of rainfall, just 17% of its normal amount. It was much drier than the previous driest October in 1965 (in the era with reliable record, when the state received 56mm). This was part of the driest spring on record, and a dry and warm run of months through spring and summer.

This run of warm and dry months had major impacts on agriculture and hydroelectricity, and helped to set up a catastrophic fire season.

Rainfall extremes can be complex, and it is generally much harder to figure out what caused them than temperature extremes. So the third Australian study (ch. 25 in the review) used two different methods to compare October 2015 to the previous record.

The results showed that El Niño did affect the October climate, but human-caused climate change also played a small but significant role. Climate change probably increased the chances of Tasmania having its driest October by 25-50%.

The record-dry October appears to be linked to higher atmospheric pressure in a band around the whole southern hemisphere, which is consistent with trends over recent time.

Rainfall across Tasmania was the lowest on record across nearly the whole state.
Bureau of Meteorology

Climate change is altering our extremes

More extreme events and more broken climate records are causing many people to ask whether climate variability or climate change is to blame. But of course it is never just one of these; it is always a combination of both.

For the extreme October of 2015, while short-term weather patterns and the El Niño contributed to the extremes, breaking these climate records would have been substantially less likely without human-induced climate change.

Climate change has already altered the extreme weather we experience in Australia and will continue to do so over the coming years.


David Karoly, Mitchell Black, EunPa Lim and Harry Hendon all contributed to the research on which this article is based.

The Conversation

Pandora Hope, Senior research scientist, Australian Bureau of Meteorology; Andrew King, Climate Extremes Research Fellow, University of Melbourne; Guomin Wang, Research scientist, Australian Bureau of Meteorology; Julie Arblaster, Associate Professor, Monash University, and Michael Grose, Climate Projections Scientist, CSIRO

This article was originally published on The Conversation. Read the original article.