Keeping it cool: Rooftop farms take on the city heat | urbanrooftopfarm

The midday sun beats down on a farmer harvesting bright red tomatoes, ripe for the picking. Behind her however, isn’t the New Territories landscape with a herd of cows grazing on an endless field of green, you probably have pictured.

Instead, towering blocks of concrete loom in the background as she snips off another luscious tomato hanging from a plant, and drops it into her bag, bulging with other fresh produce.

These urban farms, which have been cropping up on rooftops of the city’s skyscrapers, do not only provide residents with fresh, locally produced fruit and vegetables.

They also undertake the work of combating a bigger challenge, to tackle what academics call an alarming climate change problem — the urban heat island effect.

Taking on the heat

The effect, a consequence of excessive urbanization, means that heat is rapidly absorbed and retained by concrete buildings during the day. At night, heat becomes trapped because of the dense urban environment, resulting in warmer temperatures.

“Our summers are getting hotter and hotter, and it’s basically the nights that are more hot than the days…if the heat refuses to dissipate at night, then it’s a very serious problem,” says Professor Jim Chi Yung, chair professor of the Department of Geography at the University of Hong Kong.

Rooftop vegetation acts as a buffer to absorb the heat to reduce temperatures, but the smattering of a couple dozen green roofs isn’t enough to take on the heat.

According to data by the Hong Kong Observatory, the average temperature has been rising at a faster rate in the past century than it ever has before, with rates comparable to the global average.

Friday, March 20, marks the first day of Spring, but many in Hong Kong feel the city has skipped the entire season altogether.

“I only feel the heat, and more heat. It’s like Hong Kong went from winter to summer, just like that,” says Kathleen Kwan, a retiree, referring to the day’s temperature at 27 degrees celsius — an abnormal high for springtime.

As a result, Hong Kong citizens can’t help but crank up the air conditioning, a move that only further aggravates global warming.

Energy plants end up burning more fossil fuel, emitting harmful greenhouse gases in order to meet the demand. Data from the Electric and Mechanical Services Department show that electricity consumption per capita has jumped by 20% since 1997.

via Keeping it cool: Rooftop farms take on the city heat | urbanrooftopfarm.