This entry is from Ryan Merry, a senior Biology and Environmental Science major at the University of St. Thomas.
When the weather is scorching hot, which is occurring more frequently due to global climate change, it is human intuition to find refuge under cool shade trees or by refreshing water sources. Moving beyond human intuition to combat urban heat waves, a new science is developing which investigates how nature’s own cooling systems can be used to mitigate the effects of global warming. Although this research is still in its infancy, an analysis of to what degree (literally in this case) green spaces can cool the urban environment looks promising and shows that decreases of 0.94° centigrade, or around 2° Fahrenheit, are achievable (Bowler et. al. 2010). A 2° decrease may not seem substantial, but your heating bill over the entire summer may say otherwise. Urban greening may also help decrease heat wave disasters such as that in France back in 2003, which had its largest effect in the urban area of Paris and increased the death rate by 147% over the course of the temperature spike (Vandentorren et al. 2004). Why are urban areas at higher risk during a heat crisis? Bowler et. al. (2010) found that the city’s many heat absorbing surfaces capture the sun’s energy, creating an “urban heat island effect”. This urban heat island effect creates higher temperatures in urban areas than in the surrounding countryside. However if green spaces are incorporated into the cityscape, Bowler found mounting evidence that a cooling effect can be achieved in an area within 500 of the green space through shade, mitigation of energy absorbance, and humidity released through plant photosynthesis. Oak or maple could be used to cool in urban greening, but apple or pear trees can also provide a cooling service with some added produce benefits.
Instead of landscaping to create green spaces in the traditional way, the possibility exists to integrate urban agriculture and urban greening and foodscape the city. In scientific terms, a foodscape is a study of how food is available to consumers and the effect that has an eating habits (Morgan & Sonnino 2010), but foodscaping would be the conscious effort to integrate more permanent food systems into urban environments. New foodscape parks could plant (instead of oak tree after oak tree) nut trees such as chestnut or pecans and a wealth of fruits. This would not only increase the biodiversity of city parks, but provide the services of the other trees (shade, cooling, and recreation) while also providing food at certain times of the year! There is also not a restriction to food trees. Foodscapers could incorporate hedges of blueberry or currant, and ponds could become temperature cooling cranberry bogs or fish hatcheries.
Integral to the success of foodscaping would be the perpetual access to these production areas to the public. Fencing in a foodscaped park and restricting access would deny citizens the benefit of recreation and cooling. However, how could a city possibly manage a landscape that needs care and attention to also produce food under a limited budget? Could foodscaping ever occur in an urban setting? A group in Seattle Washington has found the answers to these questions, where 30 city parks exist that have fruit trees which are the result of either new community garden plantings or absorption of old “heritage” orchards into the city limits. Seattle could not afford upkeep of these trees, so a group called City Fruit received a grant from the Washington Department of Natural Resources and U.S. Forest Service to maintain and care for the fruiting trees. In 2014 the group harvested 8,221 lbs of plums, 6,622 lbs of apples, 4,715 lbs of pears, and 7 other fruits for a total of 22,000 lbs of fruit donated to 39 different Seattle food shelves and all from public city parks.
City Fruit volunteer pruning an urban fruit tree in Seattle, WA. Picture: http://cityfruit.org/programs/orchard-stewards/
This Seattle example shows that it is possible and extremely beneficial to incorporate food into green spaces, and it can create the dual benefit of edible production and urban cooling. Delicious fruit is an easy sell for urban residents, and public interest and volunteering for such projects with a dangling carrot (or perhaps an apple) of fruits for their labor would not be difficult. My hope in the future is that you can go for a walk in the park to escape the heat of the day and pick a snack for yourself along the way, because why not grow your plum and eat it too?
