The Earth Story

A visit to Sue the T-Rex and the Field Museum of Chicago fossil preparation and paleontology rooms.

Most of us aren't going to be able to fly anywhere any time soon, but here's a view of what flights used to look like out the front window of a plane. This nighttime voyage on an Air France flight starts off in Chicago and flies over the Great Lakes and eventually Montreal Canada before heading out on the rest of its trip.

Reflecting sun Taken from a flight coming in towards Chicago airport, this wonderful picture shows the sun's rays passing under the layer of stratus cloud and reflecting back up towards the plane through a window in the cloud, producing a beautiful stream of coloured rays. Loz Image credit: Mark Hersch

Sunrise over Chicago

The Value of Green

This is a green roof atop city hall in Chicago. Green roofs are one example of what is termed “Urban agriculture”; growing plants in densely populated urban areas to take advantage of the things that plants naturally do. A new study used satellite data to survey around the world, hunting for urban agriculture, and then applied economic calculations to see how much it was actually worth.

In this study, urban agriculture consists of green roofs like this, grown atop buildings, making use of vacant space in cities, or agriculture along the edges of buildings as you might see from people growing plants on a balcony. The largest of these at present, by far, is growing plants on vacant space inside city limits.

There are a number of potential economic benefits to urban agriculture. Green roofs like these provide insulation to help keep buildings cool in summers and warm in winters. Plants help limit the urban heat island effect, where dense buildings absorb sunlight and become extra hot during the day, leading to increased energy use to control temperatures and sometimes actually harming people’s health. Growing plants limits water runoff, cutting into flood risk and reducing the load on sewer systems, and helps establish soil that can support trees or other plants. Plants also will help remove pollutants such as nitrates from the air and water, and help fertilize the soil, cleaning the city and reducing the amount of fertilizer used. Finally, if edible plants are available, the food grown at these sites can be sold, making fresh foods available with little to no travel distance required to get them to consumers.

In their survey of urban agriculture across the world, this international team of scientists finds that as of the years 2009-2011, urban agriculture contributes about $33 billion worth of value globally. The largest portions of this are due to soil formation/preventing fertilizer use and due to regulation of climates and insulation inside cities.

They also apply basic estimates of the available roof and open space in cities globally to ask what is possible for green infrastructure if these features continue to be scaled up. About 20% of the roofs in Toronto were estimated as available for urban agriculture, and other cities they tested had slightly more available space. Adopting the value for Toronto, they find that continued scaling up of urban agriculture could be scaled up to values of $80-$160 billion in value globally, if local governments make efforts to implement it at larger scales.

-JBB

Image credit: http://bit.ly/2D90ijB

Original paper: http://bit.ly/2DAwixv

Winter at the railyards near downtown Chicago

Wall of water marches across buildings on its way to Chicago’s Grant Park and Lake Michigan.