How have human activities transformed the phosphorus cycle? (4/4)

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Clip Guide

: Here you will find clear descriptions of what you just saw, how they know what they said they knew, why they know it to be trustworthy information. Finally we will ask the question, "So what!" and explore why the information is important.

WHAT do we know?

In this clip from the public 2009 presentation “Agriculture After Norman Borlaug, ” Dr. Crews describes how the rise of fossil fuels has enabled large scale extraction of concentrated reserves of phosphorus through mining. This has enabled farmers, primarily in industrialized countries, to apply increasing amounts of phosphorus to soil, far beyond what was possible in the past with techniques of phosphorus concentration. The result of this phenomenon is a major transformation of the global phosphorus cycle.

HOW

Dr. Crew's draws his conclusions from existing studies and reports produced by reliable sources, such as the scientific report from Cordell et al1, which shows an increase in the use of phosphate rock based fertilizers.

1Cordell, D., et al., "The story of phosphorus: Global food security and food for thought." Global Environ. Change (2009), doi:10.1016/j.gloenvcha.2008.10.009

WHY

The tremendous increase in fossil fuel consumption is a trend that has been well documented by industry data. One example is the accompanying rendering based on data compiled by Vaclav Smil (Smil, 20101). Similar data is available on the use of mined phosphate rock based on data compiled by academics and organizations over the last 40 years (Cordell, 20082).

1 Smil, Vaclav. Energy Transitions: History, Requirements, Prospects. Santa Barbara: 2010, Praeger.

2Cordell, D., et al., "The story of phosphorus: Global food security and food for thought." Global Environ. Change (2009), doi:10.1016/j.gloenvcha.2008.10.009

SO WHAT

Dr. Crews’ research highlights some of the profound ways in which fossil fuels have transformed systems in society and nature in profound ways. The transformation of the global phosphorus cycle is just one example. As another example, fossil fuels have enabled the industrial-scale production of nitrogen as fertilizer. While enormous societal benefits have resulted from these transformations, a range of challenges have also arisen. For example, increased runoff of nitrogen and phosphorus into freshwater ecosystems and oceans causes a rapid rate of eutrophication.

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Printable Companion Guide:

Guide New--Crews IV.pdf

Active Listening Questions

Active Listening Questions:

What does Dr. Crews point to as the fundamental driver of change to the phosphorus cycle in the last century?

Taking the Reins

taking the reins

Clip Discussion Questions

Reflect on the clip using these questions. Then, record your thoughts in a science journal or discuss them with a friend.

How have human changes to the phosphorus cycle impacted human lives and the ecosystems in which we live?

What are some of the benefits of these changes to the phosphorus cycle, and what are some of the downsides?

Clip Discission Question Printable Companion:

Discussion Questions New--Crews IV.pdf

Go Beyond:

“Thinking in Systems” PART 3 – Transformational Changes (in a system)

Recall the simple system you developed in Part 1 and augmented in Part 2 of “Thinking in Systems”
The example system in this activity is a city bike share system. In this exercise, you will be asked to consider how transformational changes may alter your system -- in either positive or negative ways.

Instructions:

1. Think about conditions that would lead to a transformation of your system—what could cause a sudden and enormous change in the quantity of inputs/outputs or the speed of processes within the system? Make a list of possible drivers of transformational change as well as possible positive and negative consequences of that change.

Example response from bike share system:

Possible drivers of transformational change:

New city policy limits vehicle traffic, pushing a significantly larger share of the population to ride bikes.
- Consequences:
  - For a period, demand overwhelms supply of shared bicycles
Bikes are retrofitted with small motors which increase the speed of trips and enable longer routes
Consequences:
- A entire new set of individuals begin to bike, leading to a dramatic increase in demand for bikes
- Longer routes lead to a much larger demand for distribution of docking stations
- Shared motorized bicycles begin to replace cars on roadways

2. Select one of the transformational changes you identified and alter your system map to characterize the changes to your system.

3. Evaluate your transformed system to determine whether it still behaves in a manner consistent with the original goals of your system. Also evaluate the extent to which transformations in the system carry external consequences that positively/negatively affect other systems.

Go Beyond Printable Companion:

Go Beyond New--Crews IV.pdf

Clip Quiz

Clip Quiz: