Mike Berners-Lee just over a decade ago wrote a book measuring the impact on climate of various goods, activities, and spending. (Mike is the brother of Tim Berners-Lee — who invented the World Wide Web. I feel a bit sorry for Mike, it would be really hard not to feel like a failure in that family). The aim of looking at the impact of nearly everything was ambitious and worth a read and think. I wouldn’t worry as much about the numbers but the idea of considering the different impacts of activities is an important one.
How Bad Is A Banana?
The book examines how much in the way of greenhouse gases are produced — the carbon footprint — of various goods and actions. The core product is a banana. Berners-Lee likes bananas so he is pleased that they are pretty low impact on climate change. If all we did was eat bananas greenhouse emissions wouldn’t be a problem. (I’m sure lack of other nutrients would be a problem but that isn’t the point).
The book is a bit old now and was written for a UK audience. I read the 2011 US edition which had some modifications for US sale. For example, the book contains both metric and imperial units. (It is a shame that the US didn’t lose the silly old-fashioned imperial units when they lost the King). The translation to the US is a challenge because greenhouse gas emissions depend on geography. Most obviously if some food is created locally it won’t need to be transported which saves on greenhouse gas. (Although transportation emissions often aren’t as significant an impact as we might guess).The form of transportation really matters though, shipping is pretty good, flying is not at all good. As such, the carbon footprint differs depending upon where you are, where the food is coming from, and crucially how it is coming.
This illustrates the challenge. Estimating a carbon footprint is really, really hard. I’m not against trying though — there is often value to rough and ready numbers. (For instance, brand valuations are very far from perfect but can be useful, see here). The point here is that the numbers in the book are relatively old, modified from UK numbers, and were always a bit rough and ready in the first place. Don’t think there is any magic to the numbers but still the general ranges can be informative. Potatoes and bread are pretty good, beef is bad as is air-freighted asparagus (which apparently is a thing).
Measuring Impact On Climate
One challenge that faces Berners-Lee is the problem of average and marginal impact. This can be usefully illustrated in energy. To take a stylized example imagine a country that had a baseline of renewables producing 50% of its needs. Fossil fuels provided the rest. So when you turn on a lamp it seems reasonable to say that 50% came from renewables and 50% from fossil fuels as this is the average.
The challenge is that the extra demand is in effect being 100% produced by fossil fuels. The 50% renewable baseline doesn’t change when you turn on the lamp as generally renewables can’t be easily fired up to meet the extra demand but more fossil fuels can easily be burnt. So if the light adds 1% to demand (it is a very big lamp) we now have 101% of the previous electricity being used. The average is still 50/101 renewable use — pretty close to 50%, yet your lamp caused a 1% increase which was all fossil fuel generated. The marginal unit of electricity, the extra bit of electricity, was all fossil fuel derived and whoever turned on the lamp should be said to bear responsibility for that.
The marginal versus average issue is a major one in a lot of economic style thinking. It causes real headaches when measuring impact on climate and any number of other impacts.
An Index Of Environmental Impact
Think of how hard it is to find the carbon footprint of everything. It gets even worse when you realize that this is far from everything tha matters environmentally. Berners-Lee ends up in the strange position of saying that plastic isn’t too bad for emissions but it really is bad nonetheless. The point being that things like disposable plastic bags aren’t terrible from a global warming perspective. But they are pretty awful on lots of other environmental dimensions.
Unfortunately, plastic tends to be so durable that it hangs around in landfill sites for centuries, clutters up the stomaches of animals and fish, transforms remote Scottish beaches into junkyards, and ends up in almost every ecosystem you can think of. But from a purely carbon perspective, its inability to rot is good news in as much as it won’t add to methane emissions from landfill…
Berners-Lee, 2011, page 82
You might argue for some sort of index with points for the various detrimental effects of activities. Weighting the index — e.g., deciding how bad plastic pollution is compared to greenhouse gas emissions — seems like a nightmare job. It doesn’t seem likely we will ever find “the right” answer but I’m more positive than many about the pursuit of measurement. Just thinking about the problems might encourage us to take positive action to improve what we can improve.
Pick Your Battles
A key point to bear in mind is the advice to pick your battles. Nothing is perfect but it doesn’t do any good to just worry without action. The idea that different activities are better or worse than others should allow focus. People can’t do everything so it is important that they target the more important things. Working really hard to save a trivial amount of CO2 isn’t sustainable. The idea is to work hard where it’ll be most effective. There is plenty that can be done. For example, if you give up air-freighted asparagus your life will just be better because you don’t need to eat asparagus plus this action will also help fight climate change.
For more on sustainability see here.
Read: Mike Berners-Less (2011) How Bad Are Bananas? The carbon footprint of everything, Greystone Books