Published on Sustainable Cities

Urban Careers and the Twenty-Ninth Day

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Lily pads on lakeA helpful way for young math students to grasp the concept of exponential growth is to look at water lilies growing on a pond. They grow exponentially and double in area each day. If they will fully cover the pond by the 30th day, on what day is the lake half covered? The twenty-ninth day[1].
This year I had the honor of teaching 4th year energy systems students who will graduate later this month (their blogs on energy issues will be presented on this site over the summer). These graduates are particularly essential. During their careers they will be part of the world’s largest ever city-building spree. Their task will be to again double the world’s cities.

In my career – the twenty-eighth day – the world’s urban population doubled from about 1.6 billion to 3.2 billion. My father’s career started in 1948 when there were less than 750 million people living in all the world’s cities (about 33% of total global population). Today’s graduates will see urban populations double from about 3.2 billion today to 6.4 billion when they retire in 2050 – they will build homes, workplaces, transportation and energy systems for more than 3 billion new urban residents: A staggering task.

For students graduating today, theirs will be the last career of doubling urban populations. We’ve reached the twenty-ninth day.  By the end of their careers we will have locked in our future.
Hopefully by 2050 population growth will have stabilized and GHG emissions will have already started to decline.  A few big questions remain: how many species will we lose; where and when will global population peak (the range is somewhere between 8 billion in 2070 to 15 billion+ beyond 2020); and what will the quality of life be for the world’s poorest quintile (the true measure of success). Nothing contributes more toward good outcomes on these questions than how well today’s graduates do their job of planning, building and managing cities.
We know that we will end up with an urban planet – this is actually a good thing. True, people in cities, especially the ones with money, are the main cause of the really tough environmental challenges we face today like biodiversity loss and climate change. But cities are also the most efficient way to provide services like water and housing, and they are the economic drivers.
We face enormous challenges. Today’s youth are graduating into economies with debilitating levels of youth unemployment, many are in danger of being part of a ‘lost generation’. Uncertainty immobilizes many of our leaders and corporate bastions. We will almost certainly overshoot 2, 3 and maybe even 4 degree increases in global warming. And yet on campuses all around the world, hope springs eternal.
At least two things offer hope: our graduates and our cities.  Together they have the ability to safeguard our future.

  [1] The Twenty-Ninth Day, 1979 by Lester Brown first discussed sustainable development through the lily-pond metaphor.

Photo source: Shutterstock


Dan Hoornweg

Professor and Jeff Boyce Research Chair, University of Ontario Institute of Technology

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