The climate is becoming more unpredictable and fierce with each passing year.
Extreme weather and natural disasters like bushfires, storms, floods and cyclones can have a devastating impact on communities, businesses, homes, and public infrastructure. How can plants and living infrastructure play a role in mitigating this change and help to create more climate resilient cities?
According to the Australian Bureau of Meteorology, June 2016 was the second-wettest month on record. Wild storms lashed the east coast, triggering flooding across Queensland, New South Wales, the ACT, Victoria and Tasmania, and causing widespread damage and destruction.
June was a bad month, both here in Australia and overseas. Around the same time, America’s south-west was ablaze with wildfires spurred by continuous high temperatures, drought and winds in the region. Taiwan and China were hit by a typhoon, while Europe surveyed the damage after major flooding in France, Germany and Austria.
There is much research to support the claim that natural disasters pose one of the biggest threats to our cities (and regional communities) on a national and international scale.
According to a Deloitte Access Economics report, the true costs of natural disasters - including a weakened economy, financial losses, business interruptions, transport delays, stress and anxiety - are substantially higher than direct repairs and replacement costs.
This report, commissioned by the Australian Business Roundtable for Disaster Resilience and Safer Communities earlier this year, notes that between 2002-03 and 2010-11, "more than $450 million was spent each year by Australian governments to restore critical infrastructure after extreme weather events." That’s a $3.6 billion expenditure in eight years. No small sum.
Where does this money come from? After the 2011 Queensland floods, the Australian government introduced a temporary flood and cyclone reconstruction levy during the 2011-12 financial year, estimating the levy would raise around $1.8 billion.
With total expected costs for the government to be around $5.6 billion, the levy represented only a third of the total rebuilding costs. A further $2.8 billion was reprioritised through spending cuts to green programs (like the Cleaner Car Rebate), as well as $1 billion in infrastructure reprioritisation in order to fund the rebuild.
Wouldn’t it make more sense to change the way we design, build and manage our infrastructure (and budget) so we can better cope with today’s climate hazards and plan for tomorrow’s? It’s time to review our mitigation strategies and build pre-disaster resilience into business as usual.
What does resilience look like? In a piece entitled An integrative review of the built environment discipline's role in the development of society's resilience to disasters published in the International Journal of Disaster Resilience in the Built Environment, researchers described ecological resilience as the ‘the amount of disturbance an ecosystem can withstand without changing self-organised processes and structures.’
The Australian Business Roundtable for Disaster Resilience & Safer Communities describes resilience as being ‘prepared but also dynamic, flexible and quick to respond.’
So rather than manufacturing a ‘replacement method’ of resilience where damaged parts are substituted for new, wouldn’t it be better if critical infrastructure and buildings were designed to withstand more in the first place? What if this resilient design could absorb some of the impact of natural disasters and offset it, lessening the destruction caused and making ‘bouncing back’ easier to do?
When it comes to storms, floods and severe heat waves, living infrastructure is a sustainable way to build pre-disaster resilience into business as usual.
Stormwater management and flood mitigation
A 2013 study conducted on behalf of the US Department of Homeland Security found that "adopting green infrastructure as a flood mitigation strategy can save approximately $6.1 million dollars annually in flood-prone areas."
How does it work? In urban areas where streams, floodplains and wetlands have been replaced by development, fill and impermeable surfaces, the strain on conventional stormwater management increases. This leads to overflow, degraded water quality and flooding after major storms. Living infrastructure retains stormwater through infiltration (in green roofs, rain gardens, pervious surfaces and the like) and evapotranspiration from trees and other vegetation.
In fact, the Center for Clean Air Policy notes that vegetated roofs can control between "30-90% of the volume and rate of stormwater runoff, detaining 90% of volume for storms less than one inch and at least 30% for larger storms."
Combining these methods could significantly reduce the stress on our stormwater systems and help minimise the flood risk. It’s already been proven in New York, where the Department of Parks & Recreation manages around 2,500 green streets, many of which performed well during Hurricane Sandy.
Reducing the severity of urban heat waves
We know urbanisation has led to the urban heat island effect. While a few degrees more on a summer’s day might make you sweaty and uncomfortable, a heat wave in these urban hot spots means an increased risk of heat stroke and death in urban populations.
Scientists attribute around 70,000 deaths to the European heat wave of 2003, while another 700 died in the Chicago heat wave of 1995. As climate change advances, these extreme temperatures will likely become more frequent.
Living infrastructure like trees, parks, and green roofs can offset this heat through evapotranspiration and shading. One study found that by adding 10 per cent green cover in high-density residential areas in Manchester, UK, maximum surface temperatures could be kept at or below 1961–1990 baseline levels in the 2080s. That’s a big deal when the projected climate change increase is 1.7 to 3.7 degrees Celsius without a rise in greening.
Of course flood, storms and heat waves aren’t the only natural disasters we face, and living infrastructure can’t provide all the answers – but it can provide some. When combined in a holistic mitigation strategy with planning, policy, management and ‘grey infrastructure’ (energy networks, roads and bridges, sewer and water systems) upgrades, living or green infrastructure is an important part of a much needed multi-faceted approach to natural disasters.
In an article for The Journal of Sustainable Development, Jenna Tyler notes "Building disaster resilient communities requires the coordination, collaboration, and financial support of various government entities." It also requires industry and private sector leadership – particularly in Australia – because politics is often fickle and budgets unpopular.
Extreme weather and natural disasters are a fact of life. When we plan, design, build, regulate and budget for these kind of events, we allow our society to focus on other things. Working resilience into business-as-usual and making it standard practice means we can focus our attention on innovation, process and efficiency – we can look to the future instead of being tied to (and cleaning up after) the past. Just imagine what we could do with that freedom.