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.

 
 
 
 

Which nations control the materials required for renewables? Meet the new energy superpowers

Solar and wind power facilities in Bitterfeld, Germany. Image: Getty.

Imagine a world where every country has not only complied with the Paris climate agreement but has moved away from fossil fuels entirely. How would such a change affect global politics?

The 20th century was dominated by coal, oil and natural gas, but a shift to zero-emission energy generation and transport means a new set of elements will become key. Solar energy, for instance, still primarily uses silicon technology, for which the major raw material is the rock quartzite. Lithium represents the key limiting resource for most batteries – while rare earth metals, in particular “lanthanides” such as neodymium, are required for the magnets in wind turbine generators. Copper is the conductor of choice for wind power, being used in the generator windings, power cables, transformers and inverters.

In considering this future it is necessary to understand who wins and loses by a switch from carbon to silicon, copper, lithium, and rare earth metals.

The countries which dominate the production of fossil fuels will mostly be familiar:

The list of countries that would become the new “renewables superpowers” contains some familiar names, but also a few wild cards. The largest reserves of quartzite (for silicon production) are found in China, the US, and Russia – but also Brazil and Norway. The US and China are also major sources of copper, although their reserves are decreasing, which has pushed Chile, Peru, Congo and Indonesia to the fore.

Chile also has, by far, the largest reserves of lithium, ahead of China, Argentina and Australia. Factoring in lower-grade “resources” – which can’t yet be extracted – bumps Bolivia and the US onto the list. Finally, rare earth resources are greatest in China, Russia, Brazil – and Vietnam.

Of all the fossil fuel producing countries, it is the US, China, Russia and Canada that could most easily transition to green energy resources. In fact it is ironic that the US, perhaps the country most politically resistant to change, might be the least affected as far as raw materials are concerned. But it is important to note that a completely new set of countries will also find their natural resources are in high demand.

An OPEC for renewables?

The Organization of the Petroleum Exporting Countries (OPEC) is a group of 14 nations that together contain almost half the world’s oil production and most of its reserves. It is possible that a related group could be created for the major producers of renewable energy raw materials, shifting power away from the Middle East and towards central Africa and, especially, South America.

This is unlikely to happen peacefully. Control of oilfields was a driver behind many 20th-century conflicts and, going back further, European colonisation was driven by a desire for new sources of food, raw materials, minerals and – later – oil. The switch to renewable energy may cause something similar. As a new group of elements become valuable for turbines, solar panels or batteries, rich countries may ensure they have secure supplies through a new era of colonisation.

China has already started what may be termed “economic colonisation”, setting up major trade agreements to ensure raw material supply. In the past decade it has made a massive investment in African mining, while more recent agreements with countries such as Peru and Chile have spread Beijing’s economic influence in South America.

Or a new era of colonisation?

Given this background, two versions of the future can be envisaged. The first possibility is the evolution of a new OPEC-style organisation with the power to control vital resources including silicon, copper, lithium, and lanthanides. The second possibility involves 21st-century colonisation of developing countries, creating super-economies. In both futures there is the possibility that rival nations could cut off access to vital renewable energy resources, just as major oil and gas producers have done in the past.


On the positive side there is a significant difference between fossil fuels and the chemical elements needed for green energy. Oil and gas are consumable commodities. Once a natural gas power station is built, it must have a continuous supply of gas or it stops generating. Similarly, petrol-powered cars require a continued supply of crude oil to keep running.

In contrast, once a wind farm is built, electricity generation is only dependent on the wind (which won’t stop blowing any time soon) and there is no continuous need for neodymium for the magnets or copper for the generator windings. In other words solar, wind, and wave power require a one-off purchase in order to ensure long-term secure energy generation.

The shorter lifetime of cars and electronic devices means that there is an ongoing demand for lithium. Improved recycling processes would potentially overcome this continued need. Thus, once the infrastructure is in place access to coal, oil or gas can be denied, but you can’t shut off the sun or wind. It is on this basis that the US Department of Defense sees green energy as key to national security.

The ConversationA country that creates green energy infrastructure, before political and economic control shifts to a new group of “world powers”, will ensure it is less susceptible to future influence or to being held hostage by a lithium or copper giant. But late adopters will find their strategy comes at a high price. Finally, it will be important for countries with resources not to sell themselves cheaply to the first bidder in the hope of making quick money – because, as the major oil producers will find out over the next decades, nothing lasts forever.

Andrew Barron, Sêr Cymru Chair of Low Carbon Energy and Environment, Swansea University.

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