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.

 
 
 
 

North central Melbourne is becoming a test bed for smart, integrated transport

A rainy Melbourne in 2014. Image: Getty.

Integrated transport has long been the holy grail of transport engineering. Now, a project set up north of Melbourne’s downtown aims to make it a reality.

Led by the School of Engineering at the University of Melbourne, the project will create a living laboratory for developing a highly integrated, smart, multimodal transport system. The goals are to make travel more efficient, safer, cleaner and more sustainable.

Integrated transport aims to combine various modes of travel to provide seamless door-to-door services. Reduced delays, increased safety and better health can all be achieved by sharing information between users, operators and network managers. This will optimise mobility and minimise costs for travellers.

The National Connected Multimodal Transport Test Bed includes arterial roads and local streets in an area of 4.5 square kilometres in Carlton, Fitzroy and Collingwood.

Bounded by Alexandra Parade and Victoria, Hoddle and Lygon streets, this busy inner-suburban area is a perfect location to test a new generation of connected transport systems. Our growing cities will need these systems to manage their increasing traffic.

How will the test bed work?

The test bed covers all modes of transport. Since April, it has been collecting data on vehicles, cyclists, public transport, pedestrians and traffic infrastructure, such as signals and parking. The area will be equipped with advanced sensors (for measuring emissions and noise levels) and communications infrastructure (such as wireless devices on vehicles and signals).

The test bed will collect data on all aspects of transport in the inner-suburban area covered by the project. Image: author provided.

The aim is to use all this data to allow the transport system to be more responsive to disruption and more user-focused.

This is a unique opportunity for key stakeholders to work together to build a range of core technologies for collecting, integrating and processing data. This data will be used to develop advanced information-based transport services.

The project has attracted strong support from government, industry and operators.

Government will benefit by having access to information on how an integrated transport system works. This can be used to develop policies and create business models, systems and technologies for integrated mobility options.

The test bed allows industry to create and test globally relevant solutions and products. Academics and research students at the University of Melbourne are working on cutting-edge experimental studies in collaboration with leading multinationals.

This will accelerate the deployment of this technology in the real world. It also creates enormous opportunities for participation in industry up-skilling, training and education.

What are the likely benefits?

Urban transport systems need to become more adaptable and better integrated to enhance mobility. Current systems have long suffered from being disjointed and mode-centric. They are also highly vulnerable to disruption. Public transport terminals can fail to provide seamless transfers and co-ordination between modes.

This project can help transport to break out of the traditional barriers between services. The knowledge gained can be used to provide users with an integrated and intelligent transport system.

It has been difficult, however, to trial new technologies in urban transport without strong involvement from key stakeholders. An environment and platform where travellers can experience the benefits in a real-world setting is needed. The test bed enables technologies to be adapted so vehicles and infrastructure can be more responsive to real-time demand and operational conditions.


Rapid advancements in sensing and communication technologies allow for a new generation of solutions to be developed. However, artificial environments and computer simulation models lack the realism to ensure new transport technologies can be properly designed and evaluated. The living lab provides this.

The test bed will allow governments and transport operators to share data using a common information platform. People and vehicles will be able to communicate with each other and the transport infrastructure to allow the whole system to operate more intelligently. The new active transport systems will lead to safety and health benefits.

The test bed allows impacts on safety in a connected environment to be investigated. Interactions between active transport modes such as walking and cycling with connected or autonomous vehicles can be examined to ensure safety is enhanced in complex urban environments. Researchers will study the effects of warning systems such as red light violation, pedestrian movements near crossings, and bus stops.

Low-carbon mobility solutions will also be evaluated to improve sustainability and cut transport emissions.

Environmental sensors combined with traffic-measurement devices will help researchers understand the effects of various types of vehicles and congestion levels. This includes the impacts of emerging disruptive technologies such as autonomous, on-demand, shared mobility systems.

A range of indoor and outdoor sensor networks, such as Wi-Fi, will be used to trial integrated public transport services at stations and terminals. The goal is to ensure seamless transfers between modes and optimised transit operations.The Conversation

Majid Sarvi is chair in transport engineering and the professor in transport for smart cities; Gary Liddle an enterprise professor, transport; and Russell G. Thompson, an associate professor in transport engineering at the University of Melbourne.

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