More people, more concrete, and lots more heat in Phoenix
An 'urban heat island' effect, fed by the city's growth, is trapping heat and making temperatures soar.

Faye Bowers
The Christian Science Monitor
August 30, 2007

PHOENIX

Arizona is poised to take another record. It's about as unwelcome as a couple of other firsts – No. 1 in the nation for most illegal immigrants crossing the border, or No. 1 in the nation for identity thefts. This "one" directly corresponds with another No. 1 – its status as the fastest-growing state in the nation. While news of global warming becomes as common as the wheeze of air conditioners here, Phoenix is fighting a different, if related, problem. In part because of heavy growth – particularly in the Phoenix metro area – heat is being reflected, trapped, and absorbed in concrete, rooftops, and a maze of buildings that blocks wind. At the same time, there's little vegetation to absorb the heat, and high energy usage generates more.

It's called the "urban heat-island effect," and whatever the impact of global warming here, this phenomenon is sending the mercury rising. On Tuesday, Phoenix tied the all-time record of 28 days at 110 degrees or greater in one summer, reached in 1979 and again in 2002. If the temperature rises to 110 degrees one more day this year, Phoenix will set a record.

"We're forecasting 111 for Wednesday, 109 for Thursday, and 110 again on Friday," says Keith Kincaid, a forecaster with the National Weather Service here. But if the temperature doesn't hit 110 on those days, he adds, "we have had 110-degree days in September before."

This summer is hot elsewhere, to be sure. But in few places can you fry an egg on a sidewalk as quickly and thoroughly as you can here. And you'd have to fry a lot of them: Experts say the main reason the number of 110-degree-or-higher days has risen so steadily – and steeply – is rapid growth. In the 1950s, for example, the temperature rose to 110 or higher an average of 6.7 days per year. In the 1960s it was 10.3 days per year; in the 1980s it was 19 days per year, and in the 2000s (through Aug. 21, 2007), 21.9 per year, according to the National Weather Service.

For Westerners living here, it's about as much fun as an earthquake, a drought, or, well, a 110-degree day. But it does have people's attention. True, it's not as difficult as this summer's devastating floods or fires elsewhere in the US. Many people have swimming pools, and most have air conditioning. But that, too, adds to the problem of the heat-island effect, experts say.

"Every time you use that mechanical air conditioner, you're throwing hot air back into the environment," says Jay Golden, an expert on urban climate and energy at Arizona State University in Tempe. "It's not only the sun and the pavement, but we're generating more heat because of human adaptation." And that's where global warming comes in: The hotter it is, the more we need to cool off; and the more we try to cool off – with air conditioning, for instance – the more heat-trapping greenhouse gases and "waste energy" we create, feeding both phenomena.

No escape in the Phoenix nights

The lows at night are rising, too. Three decades ago, the nighttime low here was about 30 degrees cooler than the days. Today, it is on average only 20 degrees cooler. That's because cities are slower to cool off at night, retaining their heat in roads and buildings. Dr. Golden points to differing temperatures between downtown Phoenix and a rural weather station at the Casa Grande National Monument, about 50 miles southeast. In 1950, he says, it was only six degrees warmer in Phoenix than at the Casa Grande Monument. By 2000, the temperature in Phoenix was 12 degrees higher. Now, it is almost 14 degrees warmer in the city than in the adjacent rural areas.

That has a huge impact on water consumption and electricity generation, he says. Researchers in his department recently calculated the correlation between nighttime temperatures and water consumption. "A one-degree nighttime [temperature] increase equals 677 gallons more on average per household per year," he says – due as much to evaporation from pools, irrigation, and agriculture as to human consumption. Golden and his colleagues study these rises in temperatures for urban areas from here to London and Beijing.

"We are trying to do two things," Golden says. "One is to quantify the impacts from this national trend of climate change in the broad context…. Then, we try to provide policymakers sound science and engineering to understand what the impacts are."

Looking toward solutions

Here in the Phoenix area, for example, 40 percent of the heat-island effect is due to paved surfaces, according to Golden. "We're trying to transition to pervious pavement, which would allow for water penetration," he says.
That, he adds, would support the growth of urban vegetation, which is typically removed for new building projects. And urban vegetation planted at intervals, as well as the water pervious pavement retains, would lead to cooler temperatures at night.

"If we were to take all the surfaced parking lots in this city and cover them with 50 percent tree cover," that would significantly decrease the surface temperatures, he says. His department is also studying the survival methods of this area's early inhabitants, such as the Hohokam with their earthen structures.

Today, two-story houses are popular, he says. But what if policymakers were to ban future building of two-story houses – or at least upper floors – in order to make buildings shorter, and less prone to trapping heat. Instead, housing plans could include basements, he says, which would naturally remain cooler – though the prospect of lower levels has long been considered too expensive or difficult, despite the plethora of inground pools. The good news about these rises in temperatures, if there is any, Golden says, is that local governments are beginning to pay attention to how they design cities, how closely they space houses, and how much forestry and agriculture they plan.

Phoenix, for example, is pushing for more open-space parks with trees downtown. And the city of Mesa is offering $500 rebates to residents who convert their yards from lawns to xeriscape, including desert trees that provide canopy shade.

http://www.csmonitor.com/2007/0830/p01s01-wogi.htm

Ontario Government Helps Cities Plant Trees To Fight Climate Change Cleaner Air And Water, Energy Conservation Among Benefits

LONDON, ON, Aug. 22 /CNW/ - The planting of native trees in urban areas means cleaner, healthier cities that are fighting the effects of climate change, Natural Resources Minister David Ramsay announced today. "Trees clean the air and water, provide shade and wind protection, supply habitat for birds and wildlife and make our cities beautiful," said Ramsay.

"Supporting tree planting on publicly accessible land will expand our urban forests and reduce the effects of climate change on Ontario's cities." The province is investing $1 million over two years in a partnership with Evergreen, a national non-profit environmental organization that works with people to create and sustain healthy, natural outdoor spaces in cities. The province-wide program will support the planting of 100,000 trees in urban areas such as parklands, conservation areas, publicly accessible corporate lands and industrial parks, university campuses, hospital grounds, road allowances, boulevards and medians.

Evergreen will grant funds to groups for the purchase of trees native to Ontario, facilitate tree plantings, and provide education and outreach to involve community volunteers and citizens in tree planting. As well, the program will work with existing provincial partners involved in tree planting and environmental initiatives such as stewardship councils for advice and
support.

"Evergreen works with hundreds of communities and schools across Ontario to bring nature back to our cities," says Geoff Cape, executive director, Evergreen. "Evergreen focuses on educating people through direct participation: by planting a tree, individuals can see they are making a difference, which leads them to other ways they can improve their local environment. It's a sustainable model with long-term impact, which is why Evergreen is delighted to partner with the Province of Ontario to address climate change through individual and community action."

Proposals to Evergreen for grants will be required to demonstrate:
- Good matching of tree species to the site, good care of trees after planting, and regular monitoring of planting sites
- Significant numbers of native trees planted
- Engagement of the community in tree planting, and
- For tree planting around buildings, a focus on improving energy conservation, where feasible, through the placement of trees and choice of species to provide shade in summer and sun penetration in winter.

"The planting of urban trees is one more important element in our government's overall plan to fight climate change," said Environment Minister Laurel Broten. "Urban trees capture carbon, improve air quality and help prevent cities from becoming heat islands. It's a simple, natural strategy, yet it benefits us in so many ways over the long term." This is just one more example of how, working together, Ontarians are achieving results in ensuring a healthier natural environment and mitigating the effects of climate change. Other initiatives include:

- Planting 50 million trees in southern Ontario by 2020
- Making $220 million in loans and grants available to help municipalities reduce greenhouse gas emissions by improving and retrofitting buildings
- Setting ambitious but realistic targets to reduce greenhouse gases below 1990 levels - six per cent by 2014, 15 per cent by 2020 and an 80 per cent reduction by 2050.


Backgrounder
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ADDRESSING CLIMATE CHANGE: URBAN TREE PLANTING PROGRAM

The Ontario government is committed to fighting climate change and greening the province. While 80 per cent of Ontarians live in urban areas, our urban forests are under increasing stress from expanding development, climate change and air pollution. Planting more native trees in Ontario cities will improve air and water quality, increase energy conservation, provide habitat for birds and wildlife, and moderate the urban climate and the stress of urban life. The program will encourage people to plant trees in cities across the province. It will foster a healthier environment while building awareness of the important benefits that trees and the urban forest bring to our daily lives among individuals, families, school groups and community organizations.

The Urban Tree Planting Program
Tree Planting
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- Over a two-year period - 2007-2008 and 2008-2009 - the Ministry of Natural Resources will invest $1 million and partner with the organization Evergreen to enable 100,000 trees to be planted in Ontario's urban green spaces.

- Evergreen is a national, not-for-profit charitable organization whose mission is to bring people and nature together for the benefit of both. Evergreen has distributed nearly $2.5 million in direct grants, in addition to expert assistance, to help transform over 2,800 school grounds and public spaces across Canada.

- Tree planting activities will be done on parklands, school grounds, conservation areas, corporate lands and industrial parks with public access, university campuses, hospital grounds, rooftops and road allowances, boulevards and medians.

- Groups will be invited to submit proposals to Evergreen for funding to buy native trees. The trees will be about one metre tall to help ensure their survival in urban conditions.

Proposals will be assessed using four main criteria:
- commitment to good site-selection, post-planting care and site monitoring
- number of native trees planted
- level of community engagement, and
- improving energy conservation, where feasible, through tree planting activities around buildings that provide shade in the summer and sun in the winter.

- All planting plans must be reviewed by a qualified forester, landscape architect or equivalent professional.

- The program will engage the province's existing partners, such as the Trees Ontario Foundation, and tie into existing provincial initiatives including stewardship councils and the Community Fisheries and Wildlife Involvement Program grants. Evergreen will work with partners to identify suitable native species and to find appropriate sites for urban planting.

- The program is designed to involve people of all ages and backgrounds in planting a tree native to their part of the province.


Education and Outreach
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- Evergreen will host up to 50 workshops over the two-year period, to build the capacity of environmental stewardship groups, social service agencies, schools and others to plan, implement and steward successful community naturalization projects.

- Evergreen will support a province-wide media campaign to raise
awareness and encourage broad participation.

Contact:
Stuart Mallany
Regional Strategic Development
705-755-3205