If Australia wants to stay cool, it should stop land clearances and plant some trees

Koala bears are among the cuter victims of land clearances. Image: Getty.

Land clearance is on the rise in Australian states like Queensland and New South Wales, with land clearing laws being fiercely debated.

In Queensland in 2013–14, 278,000 hectares of native vegetation were cleared: an area 1.2 times the size of the Australian Capital Territory. A further 296,000ha were cleared in 2014–15. These are the highest rates of deforestation in the developed world.

Land clearing on this scale is bad for a whole host of reasons. But our research shows that it is also likely to make parts of Australia warmer and drier, adding to the effects of climate change.

How do trees change the climate?

Land clearing releases greenhouse gases into the atmosphere, but the effect of land clearing on climate goes well beyond carbon emissions. It causes warming locally, regionally and even globally, and it changes rainfall by altering the circulation of heat and moisture.

Trees evaporate more water than any other vegetation type – up to 10 times more than crops and pastures. This is because trees have root systems that can access moisture deep within the soil. Crops and pastures have 70 per cent of their roots in the top 30cm of the soil, while trees and other woody plants have 43 per cent of their roots in the deeper part of the soil.

The increased evaporation and rough surface of trees creates moist, turbulent layers in the lower atmosphere. This reduces temperatures and contributes to cloud formation and increased rainfall. The increased rainfall then provides more moisture to soils and vegetation.

The clearing of deep-rooted native vegetation for shallow-rooted crops and pastures diminishes this process, resulting in a warmer and drier climate.

We can see this process at work along the “bunny fence” in southwest Western Australia, where there is a moister atmosphere and more clouds over native vegetation compared with nearby farming areas during summer.

The rabbit-proof fence, which keeps pests from the rest of Australia out of the Western Australian pastoral lands. Image: Rougengineer/Wikimedia Commons.

Studies in Amazonia also indicate that, as deforestation expands, rainfall declines. A tipping point may be reached when deforestation reaches 30-50 per cent, after which rainfall is substantially reduced. Complete deforestation results in the greatest decline in rainfall.

More trees, cooler moister climate

We wanted to know how land clearing could affect Australia’s climate in the future. We did this by modelling two scenarios for different amounts of land clearing, using models developed by CSIRO.

In the first scenario, crops and pasture expand in the semi-arid regions of eastern and southwest Australia. The second scenario limits crops and pastures to highly productive lands, and partially restores less productive lands to savanna woodlands.


We found that restoring trees to parts of Australia would reduce surface temperatures by up to 1.6℃, especially in western Queensland and NSW.

We also found that more trees reduced the overall climate-induced warming from 4.1℃ to 3.2℃ between 2050 and 2100.

Replanting trees could increase summer rainfall by 10 per cent overall, and by up to 15.2 per cent in the southwest. We found soil moisture would increase by around 20 per cent in replanted regions.

Our study doesn’t mean replanting all farmed land with trees: just areas that are less productive and less cost-effective to farm intensively. In our scenario, the areas that are restored in western Queensland and NSW would need a tree density of around 40 per cent, which would allow a grassy understorey to be maintained. This would allow some production to continue such as cattle grazing at lower numbers or carbon farming.

Political and social challenges

Limiting land clearing represents a major challenge for Australia’s policymakers and farming communities. The growing pressure to clear reflects a narrow economic focus on achieving short- to medium-term returns by expanding agriculture to meet the growing global demand for food and fibre.

However, temperatures are already increasing, and rainfall is decreasing over large areas of eastern and southwest Australia. Tree clearing coupled with climate change will make growing crops and raising livestock even harder.

Balancing farming with managing climate change would give land owners on marginal land new options for income generation, while the most efficient agricultural land would remain in production. This would need a combination of regulation and long-term financial incentives.

The climate benefits of limiting land clearing must play a bigger part in land management as Australia’s climate becomes hotter and drier. Remnant vegetation needs to be conserved and extensive areas of regrowth must be allowed to regenerate.

And where regeneration is not possible, we’ll have to plant large numbers of trees.The Conversation

Clive McAlpine is a professor, Leonie Seabrook a landscape ecologist and Jozef Syktus a principal research fellow in the Global Change Institute at the The University of Queensland.

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

 
 
 
 

Southern Rail is resuming full service – but how did the company's industrial relations get so bad?

A happy day last August. Image: Getty.

“I cannot simply operate outside the law, however much I might be tempted to, however much people might want me to,” a pained Chris Grayling said on TV on 13 December. As the first all-out drivers’ strike shut down the entirety of Southern’s network, the transport secretary insisted to interviewers he was powerless in this struggle between unions and a private rail operator.

But rewind to February and Grayling’s Department for Transport was putting out a very different message. “Over the next three years we’re going to be having punch-ups and we will see industrial action and I want your support,” Peter Wilkinson, the Department’s passenger services director, told a public meeting:

“We have got to break them. [Train drivers] have all borrowed money to buy cars and got credit cards. They can’t afford to spend too long on strike and I will push them into that place. They will have to decide if they want to give a good service or get the hell out of my industry.”

Wilkinson was forced to apologise for his comments. But when Southern began to implement driver-only operation, replacing conductors with non-safety-critical “on-board supervisors”, unions weren’t convinced by claims it was all about improved customer service. “This is a national fight – we’re not going to let them pick off one group of workers at a time,” a spokesman for the rail union RMT said in April.

The strikes have been repeatedly characterised as being about who opens and closes train doors. Journalists might consider this the best way to capture the distinction between different modes of train operation – but it’s also the easiest way to dismiss and ridicule the dispute.

The reality is that with driver-only operation, all operational functions are removed from conductors. It’s then left to drivers to assess – at each station – whether it’s safe to leave the platform. Aslef, the train drivers’ union, says this requires its members to look at dozens of CCTV images in a matter of seconds. And ultimately, trains can run with just the driver.

While Southern has promised not to dismiss its current workforce, unions fear that removing the guarantee of a second member of staff will eventually lead to them being ditched altogether. Who would look after passengers if the driver became incapacitated?

In an article, BBC political editor Laura Kuenssberg suggested the dispute was also fuelled by rivalry between the RMT, which represents the conductors, and Aslef. Though the relationship between the two unions hasn’t always been easy, she misses the point entirely.

At a TUC fringe meeting in 2014, I watched RMT delegates accuse drivers of being happy to accept pay-rises in exchange for implementing driver-only operation. Aslef insisted this was not its approach, and the following year the union’s conference endorsed a motion calling for no extension of the method, and for guards to be restored where they had already been axed.

Surely the real theme of the Southern dispute is the unity of the workforce. Conductors are striking against de-skilling, drivers are striking against taking on additional duties, and the mandate for action among both groups is overwhelming.

It’s true, however, that a walk-out of drivers can have a much bigger impact than a conductors’ strike – given that 60 per cent of Southern services are already driver-only. And this is why Southern’s owner Govia Thameslink Railway, Britain’s worst-performing railway, has been so keen to prevent Aslef from going on strike. When Gatwick Express (also part of GTR) drivers refused to drive new 12-carriage trains without guards in April, the company secured a court injunction preventing striking over driver-only trains. It did so again in June after drivers voted to strike, with the High Court agreeing the ballot had included drivers on irrelevant routes.


When drivers balloted again in August, lawyers went over the ballot with a fine tooth-comb and forced the union to re-ballot over a technicality, fittingly, about doors. This week’s strike was only allowed because first the High Court, and then the Court of Appeal, ruled it was not an infringement of EU freedom of movement laws. When GTR launched this bid in the courts, a senior trade unionist told me it was in “wanky wonderland” if it thought it would win.

You’d think such expensive litigation would be risky for a company facing the ire of frustrated passengers. Things have got so bad some have moved house or switched to driving to work instead. But GTR, unlike most of Britain’s private railways, doesn’t operate on the normal franchise model. Rather than collecting fare revenue, the company is paid a set fee by the government – and so it has far lesser risks.

Critics say this has made Southern ideal as a test-ground for taking on the unions over driver-only operation, claiming the government wants to make it national as part of a cost-cutting drive.

But even with such a good deal on a plate, chaos has followed Southern bosses everywhere. At the Transport Select Committee in July, the firm faced heavy criticism for failing to recruit enough staff at the start of the contract. Southern has accused unions of unofficial action through high levels of staff sickness. But are these really a surprise when industrial relations are so bad and workers are threatened with the sack?

The Committee issued a withering report – but that was where its powers stopped. Transport secretary Grayling is also refusing to act, and the company is, after all, owned by a FTSE 250 firm and a French transport group. The only people with the power to do anything, it seems, are the workers. As hell-raising as their strike may be, perhaps it’s time we celebrated it.

Conrad Landin is the Morning Star's industrial correspondent. This article previously appeared on our sister site, the Staggers.

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