Bathtub dynamics and climate change

In Understanding public complacency about climate change, Sterman & Sweeney speculate that:

Low public support for mitigation policies may arise from misconceptions of climate dynamics rather than high discount rates or uncertainty about the impact of climate change. 

In the study they investigate the sorts of errors people make with "simple" stocks and flows problems, since these sorts of problems are fundamental to understanding the climate and climate change. 

Here's an example of one their tests:

After a bit of education about climate and climate dynamics, participants are shown the top chart and asked to fill in the bottom chart.  That is, given a scenario of future CO2 concentration what would be the corresponding emissions and removal rate of CO2. They have to extend the emissions line to the right, and also draw in the corresponding net removal rate, so that the top chart is explained by the bottom.

Their study finds that most people fail this test.  They assume that if the CO2 concentration rises a little and then levels off, so too must the emissions have risen and then levelled off.  Most people keep the removal rate constant or have it rise and level off too and they keep it well below the emission rate.

If you haven't spotted why these answers are wrong yet, think about bathtubs.  (This is a popular metaphor used by Sterman and Sweeney elsewhere.  See below.)  We can think of the above example in terms of a bathtub.  Replace the atmosphere with a bathtub and CO2 with water.  Now, the emission rate is the rate water is flowing into the tub from the tap, removal rate is the rate water flows out the drain, and CO2 concentration is the water level. 

In the example above, the question is: given that the water level rises but eventually stops rising and stabilises, what needs to happen to the rate of the water from the tap and through the drain Obviously if the water level stabilises eventually then both the rate the water is running into the tub and the rate the water is draining out must converge.  I think you can work the rest out for yourself. 

That these kinds of problems (systems thinking) are so tricky to answer correctly means we likely have the wrong intuitions of climate dynamics.  We may think certain climate change mitigation strategies are effective enough even when they aren't at all.  The sort of thinking that leads to you to the wrong answers above would also lead you to be in favour of a strategy that simply stops are CO2 emissions from rising from today's levels as a way to stop CO2 concentration from rising.  Wrong.  They have to drop, and drop dramatically enough to reach the removal rate.  And that's only the explanation that you get without invoking all the other, even trickier bits of systems dynamics like feedbacks and delays.

This study is cool because it isolates a class of tricky concepts that are fundamental to understanding climate change and its mitigation.  The suggestion is that if we could only teach people basic systems dynamics concepts then they'd make the right decisions.  We've seen this is not the case entirely, but I suspect it's part of it.

In any case, this paper gives me the framework for a study.  It gives me something concrete to measure and something concrete to teach.  I can imagine a study where I measure how well students do on these sorts of "bathtub dynamics" tests before and after they use the tool/visualisation/etc.. I develop.  

Cool, I'm starting to see ground.

As I mentioned above, the bathtub metaphor is one that's been used quite a bit.  Here are some very interesting and relevant links:

• Linda Booth Sweeney's recent blog post on the subject. A great post about bathtub dynamics and climate change, with some excellent (but broken) links at the end which I'll repeat here (but fixed, of course).
• John Sterman's interactive bathtub dynamics and greenhouse gas emissions simulator.  This basically steals all my recent ideas for climate change teaching tools and knits them together into a really slick flash application.  You get a bit of background and a few simple demonstrations/experiments that drill the stocks and flows concepts in.  
• A simple and fun bathtub dynamics climate model from SEED that puts you in a similar situation to the test I describe above, and then allows you to see future predictions under three different mitigation scenarios. 
• And finally, an cool looking blog associated with an exceptionally cool looking initiative called climate interactive. The project here is to create climate simulations (and entire simulation platform) that have "engaging interfaces and compelling output displays" with the express purpose of getting these simulations out in the hands of the general public and policy makers to enable them to make better decisions.  
  
  Well now, I think I've found folks to work with, wouldn't you say?  I haven't dug much into this project yet, but as I do I'll post up what I find.  Exciting stuff.