(The citation is William S. Pease (1991). “Chemical Hazards and the Public’s Right to Know: How effective is California’s Proposition 65?” Environment 33 (10), pp. 12-20.)

I don’t really know anything about Jim Manzi. But on this particular blog the level of discourse was pretty high and the latest post was fewer than four hours old. Plus I had just attended the Gordon Research Conference on Industrial Ecology (about which I can tell you nothing or I’d have to kill you– well, let’s say, “sequester” you). So I felt both qualified and compelled to respond.

I used my real name and linked to my blog, so I decided I had better go ahead and own up.

Here are my comments, which stand alone pretty well:

A lack of understanding of an incredibly complex system (in this case, we’re talking about the whole and entire actual world) is not a legitimate argument against prudent action. In fact, it is precisely the opposite— an urgent call to action. You talk about “what a reasonable and informed person would believe to be a legitimate danger;” I counter, while you may be reasonable, you are not informed. Like it or not, climate change is not a social issue. The welfare of the world’s poor does not enter into the question. It is a physical issue, and the tools we use to understand the physical world are scientific tools.

The modern economy depends on ultraspecialization of knowledge, and the vast array of intelligent people critically studying climate have converged on what is essentially an unassailable consensus. Media-savvy crackpots notwithstanding, the people who have dedicated their lives to understanding biogeochemistry don’t have a doubt in their minds. CO2 emissions now exceed the IPCC’s 2001 worst-case scenario; ocean pH is measurably falling; and entire ecosystems depend on the integrity of coral reefs. These are not projections, they are facts.

We are effecting change on a massive scale and CANNOT predict its effect. The only responsible answer is to change our behavior. To pretend to hem and haw over the “economic costs” of changing our behavior is asinine. It adds hubris to irresponsibility. Moreover, to sugarcoat rationalizations about doing nothing with talk of the world’s poor (which don’t figure into any economic calculation by any fossil fuel user in the developed world) is as disingenuous as it is self-serving. It’s worth mentioning that SOx emissions were cut at a fraction of the projected costs; and anyway economic models are far more uncertain than physical models. So why let the economic models call the shots?

In a free world, the only way to effect change while preserving liberty is with economic force. This is a market problem with a market solution: a price on carbon. Why is that so hard to understand?

In retrospect, I don’t think I particularly raised the tone of the debate. Rather, I’m kind of shrill and whiny. The conclusion, which can be paraphrased as “why are you so stupid?” is clearly obnoxious. It’s also deliberately simplistic, as I reject economic arguments, which goes directly against some very good advice delivered at the above-mentioned conference. I do use complex sentence structures, though, which is true to form. I should probably have sat on the post for an hour or so and re-read it. But now it’s done.

Eh. Welcome to real life.

Here’s the abstract:

We present a material flow analysis (MFA) for polyethylene terephthalate (PET), a synthetic polymer, in the United States for the years 1996-2007.  We model the industrial metabolism of PET as a network of flows linking stocks and processes.  The most common worldwide use of PET is in textile production, but in the US it is increasingly used to make disposable beverage containers for transporting water, carbonated soda, and other beverages. Bottles made from PET are the most-recycled plastic product in the US by mass and by recovery rate, and thus the PET material flow system constitutes an ideal case study of polymer recycling. We find that total consumption of PET resin grew at 2.7% per year over the period of the study, reaching 5.01 million metric tons in 2007. This growth was driven largely by the beverage packaging market, which accounted for 55% of consumption in 2007. About a quarter of PET bottles are collected for recycling, a number that has fluctuated widely but kept pace with consumption.  However, domestic capacity for reclamation of post-consumer PET has not grown as quickly, leading recyclers to export increasing amounts of post-consumer material. Manufacturers have also imported secondary PET in increasing amounts. Reclaimed PET accounted for 6–9% of total resin demand throughout the study. While polymer recycling appears to be viable, efforts to improve material efficiency are confounded by low collection rates and a lack of reclamation infrastructure.

For me, one of the highlights of reading a material flow analysis is the sankey diagram, a flow diagram in which the lines representing flows have widths proportional to the magnitude of the flows.  Creating sankey diagrams has puzzled and intrigued many, because they are both a very good way to convey information and difficult to create in an automated fashion.  I used LaTeX and PS Tricks, of course, to make my sankey diagrams, about which I’ll post more soon.  But for now, here is a sneak preview of the output.  This document is programmatically generated using a data file to indicate the widths of certain primary flows.  The remaining flows are computed arithmetically by TeX.

The hard part, of course, is laying out the figure.  But I’ve convinced myself that the fruits of the hard manual (well, emacs-based) labor are worth the hassle. Click on the figure to download the PDF.

In order to do conventional least-squares fitting to you need to determine .

Step response of NIH 3T3 fibroblasts to ionomycin

For instance, the figure above shows the fluorescent intensity of some 3T3 cells to ionomycin.   The traces are normalized to the initial values.  Notice that the cells don’t recover to the levels at which they began.  I wanted to know the time constant of the decay on the tail of the trace.

I solved this problem by performing the fit inside an iterative minimum-finding function.  First I identified the point of fastest decline and selected that as the point.  Then I iterated to find the value for which minimized the norm of the error:

for best-fit A and .

y0_fit = fminbnd( @(y0) ...
                 norm( y-y0 - exp( polyval( polyfit( x, log(y-y0), 1), x))) ,...
                 -10*y(1), y(1) );

This, along with other analysis:

For a population of cells (Showing mean and standard deviation for each test point. numbers in parentheses indicate number of cells in the sample.):

TeX source

Figure [above] shows how hazards, risks, and costs are considered together in an alternatives analysis.  A successful alternatives analysis should develop and evaluate several different approaches for solving the problem at hand.  The analysis should make conspicuous consideration of hazards, the sources of hazards, and opportunities to avoid hazards, thus ensuring a precautionary footing.  The risks presented by unavoidable hazards should be analyzed using conventional methods.  Decision analytic tools should be used to compare the resulting options and weight the relevant criteria.  The results of the analysis should be reported to the public in a manner that enables informed decision making by consumers while encouraging responsible innovation by industry.  The process should be ongoing and the analysis should be improved continuously.

TeX source

Since large-scale manufacturing processes are highly integrative, with each stage depending on the output from the prior stage, the functional requirements of a single manufacturing stage can be extremely specific and large changes can be disruptive to the manufacturing chain.  An analyst considering a single manufacturing process (limited scope) may have limited flexibility in selecting alternatives.  On the other hand, an analyst considering an entire product system (broad scope) may be able to envision a much wider array of alternatives. Figure [above] shows a generic product life cycle and compares the minimal scope for an alternatives analysis to the maximal scope, which is the entire product system.

Dutch study (pdf in english) on the life cycle impacts of reusable vs disposable cups for coffee service found that hand-washed ceramic coffee cups are the most impactful way of consuming coffee, machine-washed porcelain coffee cups are the second-most impactful, and disposable single-use paper cups are the least impactful, with the notable exception of very high ozone depletion potential due to chemicals used in paper cup production. Polystyrene was middle-of-the-road.  But read on…

Looking closer, the assumptions of the study are a little eye-opening. In particular, the study assumes the reusable cups are washed after every use, and that hand-washing uses an always-on under-sink electrical water heater.  In this case, the environmental effects of the ceramic-mug system are “virtually entirely the result of using electricity” (46).  Electricity is also the culprit in dishwasher-cleaned porcelain mugs, although dishwashers are more energy efficient than standby electric water heaters.  Finally, the non-electricity-caused environmental impacts of the reusable systems come from eutrophication from detergents; non-phosphate detergents would mitigate this effect.

Most of these issues are considered in the sensitivity analysis (they didn’t talk about phosphate-free detergents).  All you coffee drinkers should be relieved to know that simply by washing your mug with cold water (which the study calls “hygienically questionable”), ceramic-mug drops to rock-bottom in terms of impact.  Even under their high-impact assumptions, washing with hot water is ok as long as you only wash after 4.5 or more uses.

The moral is that before you sneer at people drinking from disposable coffee cups (as I often do), you must first ask yourself, “are these the type of people who leave the hot water running when they do dishes and/or use a fresh cup every morning?”  If they are, maybe you should thank them for using disposables instead.

Now, back to work…

To clarify, if you want to improve the efficiency of material cycles, recycle your plastic. If your goal is to reduce your environmental impact, then recycling doesn’t help. You probably save 20% of the life-cycle energy consumption required to make the bottle. It’s better than throwing the bottle in the trash, but that’s like saying punching someone in the face is better than shooting them in the thigh. Your best bet is not to use disposable products in the first place.

Anyway, now that I’ve given my talk, I saw nothing wrong with getting hammered with bourbon at a local dive bar with my hotel-roommate, a fellow from Yale who has learned some very interesting things about LED lighting. Tomorrow the IEEE International Symposium on Sustainable Systems and Technology (ISSST) kicks off, but not until 1 PM. I plan to make full use of the intervening time sleeping.

In an era of increased consumer consciousness of environmental issues, recycling of postconsumer waste has gained prominence as a means for individuals to contribute to a sustainable society.  Plastic packaging products present particularly promising potential for postconsumer recycling owing to their high embodied energy content, their ubiquity in the market, and their longevity in landfills and the environment.  Despite these facts, in 2007 less than 7% of plastic waste was recovered for recycling in the US, making plastic the least-recycled plastic material category according to the US EPA.

As industrial ecologists, we might find that number alarming, or at least indicative of the potential for improvement.  Recycling is generally acknowledged to have environmental benefits, usually for its contribution to two main areas: first, a reduction in energy use, and second, reduced extraction of primary (virgin / non-recycled) materials.  Plastic recycling should thus be considered on the same basis– put simply, to what extent does plastic recycling displace the production of primary materials?

Read more: here is my presentation to SIEYP 2009, the first Symposium of Industrial Ecology for Young Professionals, May 17, 2009: sieyp-show