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.

 
 
 
 

Eritrea’s Modernist architecture: a striking reminder of years of oppression

Asmara’s futuristic Fiat Tagliero Building (1938) was built to resemble an aircraft. Image: David Stanley/Creative Commons.

Those with an eye for architecture will notice something peculiar when visiting Eritrea’s capital, Asmara. Dotted around the city are exceptional examples of Modernist architecture, a style that emerged in Europe during the interwar period. Rejecting gratuitous ornateness in favour of minimalism, function and rationalism, the style grew to dominate 20th century design. But it didn’t arrive in an east African country in a remotely benevolent way.

The huge continent was carved up in the span of just a few decades, in an era of history known as the “Scramble for Africa”. Described in German as torschlusspanik, meaning “panic of a closing gate”, European powers grabbed as much as they could to prevent their rivals gaining the upper hand.

Having consolidated his power in Italy, fascist dictator Mussoulini looked to Africa to expand what he saw as the new Roman Empire. It was in this context that the country seized this stretch of coast along the Red Sea that became Eritrea. And it was Asmara that was going to be the new African capital, La Piccola Roma – Little Rome.

Standing at 2,000m above sea level, the capital’s location was chosen in part because it was cooler than the brutally hot coastal regions. As was commonplace across European colonies, the colonisers wanted to avoid the extremes of the lands they conquered and find places more comparable to the climates they had left behind.

Where the colonial money arrived, the locals followed and Asmara became a city of contrasts. Intermingled with the Tukul’s, round huts of stone or mud topped with conical roofs that are indigenous to East Africa, are hundreds of buildings in the modernist style that were erected by the Italian colonisers from 1935. Many such buildings, including the Fiat Tagliero petrol station, the Town Hall and the Cinema Roma, came to represent East African Modernism. But why was there this push towards the style?


Peter Volgger, an academic who studied the impact of the modernist architecture in post-colonial Eritrea, has a theory. “Colonial cities were often projection screens for modernist fantasies and were built as futuristic visions for European cities.” So what couldn’t be done back home could be done in the colonial setting. Fantasies could be fulfilled.

The fall of fascism in Europe after WWII didn’t mark the end of colonialism in Africa, as the losers’ colonies were transferred over to the winners. Britain governed the colony for a while before power at a federal level was handed over Ethiopia. It was only in 1993 that Eritrea finally gained independence from its larger neighbour; a hundred years after the Italians first conquered the region.

Yet the Modernist buildings continued to be built long after the Italians had left. The IRGA garage, for instance, which is often held up as a key example of Eritrean modernism was built in 1961.

It’s in part due to such constructions that in 2017, Asmara was recognised as by Unesco as a site of particular cultural importance and included in their world heritage list. This not only brings in money from Unesco directly, but also induces international interest and tourism. The inclusion of Asmara in the organisation’s heritage list marked a shift towards inclusivity, having often been criticised for its lack of sites in Africa. Of the 845 cultural sites worldwide, Asmara is one of only 52 that are from Sub-Saharan Africa. In Germany alone there are 41 sites and Italy 49.

Long overdue, the significance of Asmara and its modernist buildings has been recognised. Despite their architectural interest they cannot and should not be divorced from the grim historical reality of their existence. For the millions who call the city home they stand monument to the arrogant dreams of empire that consumed the country for over a hundred years.