Tipping Points, Combusting Compost, and Cross-Disciplinary Applications

Two weekends ago, a few of my fellow MSCers and I schlepped over to the Hynes Convention Center to attend the AAASAnnual Scientific Meeting here in Boston. This was my first *big* scientific meeting.

Typically I attend regional meetings, usually held in moderate sized hotels, where several hundred marine biologists come together to present recent research findings. These small meetings are great for catching up with colleagues and getting an insider’s look at the latest and greatest research. But here, at the AAAS meeting I found myself amongst thousands of scientists, from all different disciplines, moving around the convention center to see presentations on chemistry, engineering, biology, etc. Although not the best venue for hearing about cutting edge research in marine biology it was great to hear talks in other areas of science and gain insight into cross-discipline applications.

Once such group of presentations was a session in mathematics on “Mathematics of Tipping Points: Framework, Applications, and Prediction”. The session was organized by Mary Lou Zeeman, daughter of Sir Christopher Zeeman one of many mathematicians who contributed to the theory and application of tipping points. The theory of tipping points (aka: catastrophe, bifurcation, hysteresis, etc.) describes a system, that has different states (let’s say 2) and when in a single state things change very slowly (stable equilibria) but once you reach a certain point or value (point of unstable equilibria) you “jump” into the other state.  As Marteen Schaffer, one of the session presenters, put it, your system may be changing so slowly that you don’t even notice, but eventually you reach a point that all you need is a fly to s#&@ on your system and it tips!

Diagram of Tipping Point (Catastrophe) Model; red surfaces = stable equilibrium, Blue surface = unstable equilibrium. If in one stable state, you eventually reach a node (place where red meets blue) the system becomes unstable and “jumps” (a “catastrophe”) to the next state.

You can watch this video of Sir Zeeman describing and demonstrating applications of the theory of tipping points in his 1978 Christmas Lecture. In the first 20 minutes, he gives an easily digestible explanation of tipping points theory and demonstrates the theory with the “Zeeman Machine”. In the remainder of the lecture he explains the theory’s application in engineering, physics, and psychology. (What I’d really like to know is how they got so many children to sit patiently and interestedly for an hour long lecture on math?!)

As an ecologist my first introduction to the theory of tipping points was its application in alternative stable states hypothesis describing abrupt changes in community composition leading to an alternative, but stable, community. As the session participants pointed out, the theory is gaining new interest due to its application in many new topics such as climate change. The coolest thing I learned was that tipping “rates” can actually be used rather than tipping “points”. There are many systems where the rate of change can increase or decrease in state of stable equilibrium and particular rates can cause the system to tip into a different state. Dr. Sebastian M. Wieczorek used the example of combusting compost. In the arctic, under layers of permafrost, massive amounts of peat (aka compost) are digested and processed by microbes. As these microbes breakdown organic matter and respire they give off lots of CO2. Typically this gas is released slowly into the atmosphere but if temperature rises too quickly (i.e., rate of temperature increase) the compost gets too hot and the greenhouse gases are released in huge bursts; releasing large quantities of CO2 and creating the potential for combustion. In a feedback, rising atmospheric temperatures (which are increasing due to climate change) increase peat temperature which in turn stimulates microbial activity which further increases soil temperature – creating a potential “compost bomb”. You can read a scientific article here, but you may prefer a more digestible popular article.

smoke plumes from satellite
Satellite images of smoke plumes from peat fires in Russia in 2010.


As the meeting continued over the course of the weekend I saw the concept of tipping points come up again in a session on evolution (“How Macro-Evolutionary Studies Call for an Extended Synthesis“) and climate change policy (“The National Climate Assessment: Draft Findings for 2013 and Sustaining the Process“).

Although I enjoyed all the science talks, I really appreciated the opportunity to get more information about fellowship opportunities and participate in sessions on science communication. I am particularly interested in the AAAS Mass Media Fellowship. This fellowship places you in mass media outlet for 10 weeks, during which you act as a free-lance science writer for the company and build a portfolio of published writing examples.  I was fortunate enough to be able to talk with Mass Media Fellows and all said the same thing – that the fellowship was life-changing, a sort- of tipping point in their careers. Ever since I served as an adjunct professor at community colleges, the challenge of making science understandable and (more importantly) interesting to non-scientists has been a passion of mine. While working on my Ph.D., slowly and steadily, I have been increasing my participation in outreach activities that allow me to practice my communication skills. Who knows, maybe a Mass Media Fellowship experience will tip me into the realm of reaching the masses with my science-y ramblings.



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