Poorer Urban Areas Suffer Worse Heat:

A recent study in New York community districts and United Hospital Fund neighbourhoods shows that there is a higher rate of heat-related mortality in poorer areas.

According to an article in the Harvard Gazette, there were higher heat related deaths in southern and western Bronx, central Brooklyn, northern Manhattan, and the eastern side of midtown.

The poorer residents mainly occupy these smaller heat islands. The study showed a strong correlation between excess deaths and poverty, poor housing quality, hypertension, and impervious land cover.

“It is known that there is an unequal distribution of risk from climate change around the world,” Joyce Klein Rosenthal, an assistance professor of urban design, told the Gazette. “What’s less known is that there is a significant variability of risks from climate change and extreme events within American cities, related to poverty and conditions in the built environment.”

She added that it is very important to recognise that “designers, architects, and urban planners have the capacity and agency to improve urban conditions”. Rosenthal said that by understanding vulnerability within cities, there is a better chance to implement more “effective adaptive strategies with communities”.

Several cities have already started ways to ease the heat for the most vulnerable of residents through “longstanding programs to distribute fans and air-conditioners and open cooling centres on the hottest days”.

“Studies like this provide health outcome-related evidence supporting adaptive interventions. We have health disparities in the spatial distribution of excess mortality of seniors during heat events. The types of characteristics we found to be associated [with that mortality] are within the collective ability of municipalities to intervene,” Rosenthal told the Gazette.

She said that heat, like ground-level ozone, is an environmental stressor, “unevenly distributed in places where there are less trees, less green space, and associated with poorer housing quality”.

According to the study, income levels are associated with surface temperatures. It showed that poorer neighbourhoods are hotter while wealthier neighbourhoods are cooler.

“Urban design strategies can make a difference in reducing urban micro-heat islands,” Rosenthal said.

She added that if the aging population, hotter climate, and lack of affordable housing are not addressed, it may constitute a “perfect storm for future heat wave deaths”.

Rosenthal said the study proves that greening a neighbourhood should be taken seriously. “The disciplines of the built environment – urban planning, architecture, landscape architecture, and urban design – have the knowledge and responsibility to make a difference.”

Urban Heat Islands Killing Red Maples:

Urban heat islands are doing more damage than previously known, according to a new study by the North Carolina State University.

The research shows that “urban heat islands are slowly killing red maples in the southeastern United States”. The researchers have found that “warmer temperatures increase the number of young produced by the gloomy scale insect” by 300 percent. This in turn leads to 200 times more adult ones in urban trees.

The gloomy scale insect is a problematic tree pest. It is small, immobile, has no visible legs and antennae, and they look like individual fish scales pressed tightly against the plant they are feeding on. They suck the sap from trees, removing nutrients and energy. This reduces tree growth and can eventually kill trees.

“We’d been seeing higher numbers of plant-eating insects like the gloomy scale in cities, and now we know why,” says Adam Dale, a PhD student at NC State and lead author of the paper.

“These findings also raise concerns about potential pest outbreaks as temperatures increase due to global climate change.”

The research focused on red maple trees in 26 sites in Raleigh, North Carolina as they wanted to look at the most important pest species of the most common tree species in urban areas in the southeastern United States.

“Urbanisation reduces the amount of vegetation in a habitat and increases impervious surfaces such as roads and rooftops. This can diminish predator and parasitoid communities and their ability to control pests. However, it also makes cities hotter than rural areas.”

The research found that temperature was the most important predictor of gloomy scale abundance. The warmer the area the more scale insects were found.

The researchers also said that the temperature was related to the amount of impervious surfaces in the area, including streets, sidewalks, and parking lots. “In short, the higher the percentage of impervious surface, the warmer the area.”

They said that at the coolest sites, the females were producing approximately 20 young while the warmest sites, the females were producing around 60 young.

Aside from the pest problem, the researchers also found that “higher temperatures increase stress on red maples by making it harder for them to get water from their roots to their leaves”.

“This work tells us that urban planners and foresters may need to change the way they decide which trees to plant, and select trees that are better suited to hotter conditions,” Dale says.

The researchers added that urban planners need to plant more trees and vegetation in cities to increase the shade on impervious surfaces and limit the urban heat island effect.

“It would also make sense to choose trees that are less susceptible to scales and other pest species,” he says.

A first national study by the United States Forest Service has revealed that trees are saving more than 850 human lives each year and preventing 670,000 instances of acute respiratory symptoms.

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The Difference That Urban Trees Make:

Urban developers around the world are joining in the effort to create green cities for future generations.

In an article by Ben Kaplan from We Create Here in Iowa, he mentioned the many benefits of urban trees based on a list created by Dan Burden. Burden is the co-founder of the Walkable and Livable Communities Institute – an organisation focused on creating pedestrian friendly spaces.

The story stated several benefits of urban trees. One is creating a safer environment. This is because street trees “make people drive more carefully” thereby keeping pedestrians safe and reducing stress associated with driving.

“Surprisingly, people perceive driving through areas with street trees as taking less time than driving in areas without street trees,” Kaplan noted.

Second, trees absorb greenhouse gas emissions, lowering the carbon emissions and other particulates in the air. Apart from that, “roads covered by a canopy of mature trees last 40 to 60 percent longer than roads without tree cover.”

The shade also lowers the heat island effect as canopied roads stay cooler on hot days. “Street trees also soak up a lot of water, helping to prevent street flooding and runoff.”

As we mentioned in the blog, street trees actually have more financial benefits to the city than the cost to maintain them. According to Kaplan’s article, it costs $1.2 million a year to maintain all of the 35,000 street trees in their area. But they generate $5 million of positive economic benefits each year.

“The average value per tree is $34 and in total generates $1.3 million a year. Street trees in Cedar Rapids also divert enough stormwater to save the city $1.8 million a year, reduce energy costs by $1.3 milion a year and provide $450,000 worth of air quality improvement and carbon reduction annually.”

“If you want to experience the difference street trees can make as a pedestrian, take a happy hour stroll from the Starlite Room to Belle’s Basix or 101 Gastropub, once on the tree-plentiful north side of 1^st Avenue, and walk back on the unshaded south side of the street,” Kaplan said.

Several organisations are aware of the many benefits trees provide. More recently, according to 9&10 News in Michigan, the Greening of Detroit’s Green Corps program is hiring 80 high school students to help take care of the 12,000 trees and green spaces in the city. Since it started, the program has hired more than 1,500 young people to help care for the city’s environment.

These young people will also “work to improve parks and support conservation projects while learning about agriculture and farming at The Greening’s farm gardens”.

Previously, residents of Detroit also united to create a greener city. It is these efforts from communities and organisations that will continue to push others to do their part in creating a greener future.

The heatwaves in Australia are expected to increase in the coming years, according to a PWC report.

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The State of Australian Cities:

A 2013 report examined the sustainability issues for Australia’s major cities. It said that in recent years, heatwaves, floods, fires and storms have happened more frequently in several cities in the country. Aside from climate impacts, the report also looked at the residential and transport energy use of the country.

“The energy consumed in Australia’s cities is a major element of the country’s natural resource consumption; it continues to stand out as one of our major long-term sustainability issues. While the United States and Europe show signs of leveling-off per capita energy use (and hence emissions), according to some sources, Australia shows no clear signs of a long-term trend in that direction.”

It said that Australia’s energy use and emissions have both grown along with per capita GDP. The report predicts that heat-related deaths in cities like Perth and Brisbane will only increase.

“The liveability of Australia’s cities will be affected by how their sustainability is managed.”

To reduce the Urban Heat Island (UHI) effect, many cities are making good progress in introducing plants and vegetation in metropolitan regions. For one, the South Australia Urban Forests – Million Trees Program is on track to achieve the target of three million new native plants by 2014. The program was created by the SA government to return three million local native trees and associated understorey plants to Greater Adelaide.

But there is still a long way to go. The report said that in order for the government to meet the targets of South Australia’s Strategic Plan, “re-vegetation across a scale of thousands of hectares is required in order to redress the habitat loss and absorb carbon emissions”.

The Million Trees Program is a good representation of the “long-term approach to habitat restoration and forms a strong basis for continued success and sustained effort into the future”.

A snapshot of Melbourne’s urban forest shows that there’s an expected 27 percent loss in 10 years and 44 percent loss in 20 years in useful life expectancy. There is only a 22 percent canopy coverage in the public realm. In response, Melbourne has placed key urban forest targets, including 40 percent canopy coverage by 2040. The city aims to reduce urban temperatures by two to four degrees. There will also be an expansion of stormwater harvesting to secure water supply to the urban forest.

As for Sydney, the city has developed the Greening Sydney Plan, which aims to develop and protect the city’s urban forest, improve habitat for biodiversity and to care for the urban landscape. The program will deliver 42 programs and projects in partnership with residents, local business, developers, and volunteer groups. So far, the program have planted over 8,650 new street trees since 2005 and installed 35,000 square metres of landscaping throughout the streets since 2008.

Next, more on Australia’s green roofs and walls.

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