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

The green city of Jakarta

Nirwono Joga
Jakarta

A metropolitan city, as a man-made environment, is one of the biggest contributors to carbon-dioxide (C02) -- the gas causing global warming -- as a result of traffic congestion, urban exhaust gas emission and the narrowing of the green open space. Ironically, a coastal city like Jakarta will in fact receive the biggest adverse impact of this global warming phenomenon.

Luckily, the awareness shared by the government, property developers, planners and city residents has led to a commitment to integrate a sustainable development policy in all their operational activities. Global warming has prompted green cities to compete throughout the United States and elsewhere in the world. In Indonesia, we are familiar with Adipura, the award given to the cleanest and greenest city.

Jakarta must become a green city. Right now this city is in "suicidal" mode, ecologically and urban-wise. Jakarta is marked by a degradation of its environment including coastal abrasion, sea water intrusion to buildings and roads, a clean water crisis, ground water contamination, and soil subsidence. The city undergoes chronic traffic congestion and thick air pollution. Fire accidents in densely populated residential areas reach their apex during the dry season.
Flooding will (surely) drown the city.

Experts on disaster mitigation and city planners have again sounded their warning our city's spatial layout design is yet to take disasters into account. As a result, a disaster will claim a lot of lives and inflict great material losses. With reference to Law No. 24/2007 on Disaster Management and Law No. 26/2007 on Spatial Layout Design, a city must be designed to be "disaster alert".

This refers to a city's ability to anticipate and mitigate various natural disasters (flooding, earthquake, tsunami) and non-natural disasters (fires, clean water crisis, sea water intrusion, soil subsidence, environmental pollution). A disaster policy makes a priority of urban development and how to overcome environmental quality degradation.
Disaster management is a cycle of sustainable activities rather than post-disaster recovery plans. Disaster management makes green open space the backbone of a disaster-alert city.

A green city is supported by a structured green open space network system and includes home parks/gardens, environment parks, urban parks, sports grounds, cemeteries, urban forest/botanical gardens and water-catchment areas (man-made and natural lakes and dams). To be a green city, Jakarta must be reformed so that it will be more transparent and more accountable.

The mission is simple: "If you go out of your house, you will be in a park." This mission will be spelled out in greater detail in the master plan of green open space. With reference to Law No. 26/2007 on Spatial Layout Design and Regulation of Home Minister No. 1/2007 on green open space in urban areas, the green open space of a green city must make up at least 30 per cent of the total area of a city (20 per cent of public green open space and 10 per cent of private green open space).

The establishment of new green open space areas will be necessary to significantly augment the city's "lungs" and water catchment areas. Eco-drainage and ecotourism involving man-made lakes and mangrove forests must be revitalized and developed as water catchment areas. Hardened neighborhood parks (sports ground, neighborhood security system checkpoints, parking grounds for local residents) should be better managed. The yards of schools and office buildings should be made green with grass and trees. And all green areas should ensure a better water absorption capacity. Once these steps have been implemented, those responsible should enjoy government incentives (relief in tax payment).

The green belts on free plots of land on river banks and on either side of railway lines, open space under bridges and flyovers and high-voltage channels should be restored to their original function and be freed from illegal settlers in a humane and comprehensive manner. As a result of limitation in the availability of land, the government must encourage the public to (voluntarily) live in high-rise buildings or apartments so there can be more green open space.
The awareness of the public, particularly in disaster-prone locations, must be raised so they will voluntarily move to apartments in the city and give more room for evacuation.

It is now time for the government to provide a (flyover) disaster evacuation park measuring some 500 square meters in areas crowded with people and buildings -- the places hurt most when disasters strike. In a normal situation throughout the year, the parks will serve their functions, including ecological, economic, educational and conservation functions (solar energy, biogas), as well as their esthetic function (environmental cleanliness and beauty).
Planting large trees in a great number in all corners of the city will make the city's air fresh and cool. These large trees will absorb water and provide shade to pedestrians and cyclists. They also reduce solar radiation (the greenhouse effect) and lend softness to the buildings and the city landscape.

A green city will give a number of advantages and lead to environmentally friendly and sustainable development, productivity and the culture of high competition. The city is supported by proper facilities and infrastructure, public transportation and employment opportunities. The city is geared towards being a healthy city that is energy-efficient and environmentally friendly and marked with the culture of sustainability.

The writer is chairman of Jakarta's landscape architecture study group.