Category: Reducing your impact

I think that a big problem in getting people to care about carbon dioxide pollution is how abstract it is. It is a transparent, odorless, non-toxic gas that is already naturally occurring in the environment. We don’t see it, feel it, touch it,  or experience it in any substantive way in our daily lives (see ‘Salience’ on this page) even though it is causing a global calamity. So I thought that I would go through a quick thought experiment that allows one to really visualize how much of this stuff we are producing.

In 2011, each American’s share of carbon dioxide pollution (and equivalents like methane) added up to about 24 metric tons. This isn’t an amount that is easy to think about. Our daily lives revolve around things that weigh pounds or kilograms, and we don’t often think about weight at all when it comes to gases. So though this is a good accounting method for scientists to measure carbon pollution, it isn’t useful for visualizing it. So we’ll describe it in two other ways to be able to better picture what we are doing.

As a gas at normal temperature and pressure (like the air around us), how much space would 24 tons of CO2 fill up? A quick conversion from weight to volume (calculator here) shows that the CO2 per American per year is about 450,000 cubic feet (13,000 cubic meters). This still isn’t a number that we can visualize, so lets imagine that we replaced all the air inside of a building with the CO2 that one person produces in a year. It could completely fill the living space of a 40,000 square foot building with 10′ ceilings, like the mansion below.

Or it could completely fill up a 20,000 foot warehouse with 20′ tall ceilings, like this one:

To reiterate, this is how much CO2 is produced per person each and every year. It is an absolutely enormous amount.

Or lets look at it another way. If one took that 24 tons of CO2 gas and cooled it enough, it would freeze and give you dry ice. Dry ice looks a lot like regular water ice, but it is a bit more dense. If you made one ton cubes of CO2 ice, each cube would be a bit less than 3′ (1 meter) on each side. 24 tons of dry ice would fill 530 cubic feet (15 cubic meters), enough to fill a large moving van.

When one thinks about it this way, it really starts to put things in perspective.  Because our current economies are so dependent on fossil fuels, and these fuels give off CO2 when they are burned for energy, almost every activity we do produces carbon dioxide. We need to keep this in mind, and not just think about the physical things that we touch that were produced with oil, like plastic products. Each mile traveled, each service used, they all produce carbon dioxide. We are starting to decarbonize our economies, meaning that the carbon pollution for each activity is decreasing. But we need to keep the primary goal front and center, to get the net level of CO2 that humanity produces down close to zero.

When thinking about solving the problems of sustainability, or any other complex global issue for that matter, it is easy to feel overwhelmed, even helpless. The problems are so large that one wonders whether one person can even have an impact. Don’t despair, there is much that each of us can do. I recommend that you focus on things that you are passionate about, those that you can stick with over time, and those that can make the biggest impact. Don’t tie yourself up in knots of guilt, or make changes to your life that are going to make you miserable, as that isn’t going to be productive. What we really need to do is to rally the support of whole societies, and one of the ways of doing that is to show naysayers that with sustainability you can ‘have your cake and eat it too’. This doesn’t mean that we can all live in mansions and drive massive gas guzzling cars, but we could all have homes that are wonderful to live in with readily available transport to get everywhere we need to go. We also need to accept that moving humanity to a more sustainable trajectory takes time, with the results taking years or even decades. I personally am putting together a 15 year sustainability plan for my family (to be linked once written up more fully).

Just as we must admit that it will be a long road, we are also all at different places upon that path. Someone who is just thinking about sustainability for the first time might be able to dramatically reduce their personal footprint by making those changes that constitute the ‘low hanging fruit’. For someone who has already taken many steps to reduce their own impact, their goal may instead be to convince others to improve their own practices, be it friends and family, or the businesses and government that provide us with our goods and services. People also have different means to act. If you are a renter who works long hours just to make ends meet, it may be harder to make major changes to your behavior than for someone with more time and resources at their disposal. The important thing is that each of us who cares about sustainability and the future of our world acts, and does what they can.

The details to follow about the scope of what must be done are daunting, so I want to mention just a few promising trends. Though we are currently using too much land and releasing too many greenhouse gases, there are technologies coming available that will help to solve many of the problems that earlier technologies have caused. For instance, in the realm of energy, wind and solar are now the cheapest form of energy generation in some places, and both are growing exponentially while starting to displace fossil fuel use. New agricultural technology, such as ‘precision farming’, increases yields while reducing inputs and pollution. Technology can and will do some of the heavy lifting for us, but we still need a culture that will adopt the best of technologies and practices as quickly as possible.

Where are we now? Where do we need to get to?

To understand the basic numbers of sustainability, it helps to describe them at the level of the individual – you, or any person living a modern lifestyle in a rich country. The easiest way to do this is to start with the total amounts of emissions, energy and land use, and then divide that by the number of people (I’ve done a version of this for my own family’s energy use here). This is then the average amount that is used on behalf of each person in a society. Roughly one third of that energy is personal consumption, from building and heating our homes, to driving our cars, to our food, clothes, and electronics. Another third is each person’s portion of the energy used by businesses and organizations that provide us with goods and services – a part of the energy to keep the lights on at your hospital or power a factory is being used on your behalf. Finally, everything that governments do is (at least in theory) on behalf of its citizens, so of all of the energy used to maintain roads or armies or the IRS, a chunk of that is for each and every one of us. Once we know what we are using, we can then compare those numbers with the estimates that ecologists and other scientists can give us about what sorts of levels are actually sustainable. The gap between the status quo and the sustainable level shows us the work we need to do. There are three things that I want you to consider, total energy use, greenhouse gas emissions, and land use (we’ll leave aside other resources such as water for the time-being).

Total energy use isn’t actually something that we need to worry about for its own sake. If we had infinite clean energy, every person could use as much as they want. However, we don’t live in this magical world, and there are greenhouse gas, pollution, and land use costs to all the energy that we use. Tracking energy use is relatively straightforward to do and is highly correlated to greenhouse gases and land use, there are also good records for energy use. In the US, the total consumption of energy per capita is about 230 kilowatt hours (kWh) per day. To put that in perspective, the typical house consumes about 30 kWh a day. Using energy much more wisely and efficiently could allow us, over time, to reduce this total by a factor of 3 or 4 times, down to perhaps 60 kWh per person per day. For a very in-depth dive into energy use both at a personal and national level, see this very informative video by Saul Griffith.

Greenhouse gas production is tightly linked to total energy use, especially considering how much of our energy currently comes from fossil fuels. In 2017, the American per capita production of CO2e (carbon dioxide equivalents) is about 16 tons. The overall global average is 4 tons. The 2015 Paris Climate Accord, agreed upon by virtually every nation in the world, seeks to limit global warming to no more than 2 degrees Celsius. To accomplish this requires that we reduce global per capita emissions down to less than 2 tons CO2e per person. This means that we need to figure out how to reduce our emissions in rich countries down to 1/8, or 12%, of their current level. There is an enormous amount of work to do here. The single most comprehensive examination that I’ve seen of how the world could do this is through a Project Drawdown, which outlines all of the things that could bring greenhouse gas levels down to sustainable levels.

In terms of land use, we need to have space for ourselves and to grow our agricultural and timber products, while at the same time leaving room for all of the non-human species that we share the planet with. With the human population closing in on 8 billion, there are only 5 acres per person of total land area. Humanity has now pushed into just about every nook and cranny of the planet, so we need to be good stewards. Of all that land, about 1/3 is uninhabitable desert, mountain and glacier, 1/3 is agricultural, 1/4 is forest, leaving 1/10 for everything else. Urban areas use about 1/100 of all land. Humanity is already using almost all of the prime territory for agriculture, and there is very little frontier left to grow into, especially since we want to preserve what natural spaces we have left. On top of that the world’s population is still growing, expected to reach 10 billion or more by the end of the century. Put all together, we need to reduce our impacts so that we can provide for the needs of each person on less than 2 acres of land, an area the size of two football fields. This area needs to provide all of each person’s food, as well as many of the other products that they use, wood, paper, leather, cotton, and so on. Optimally we should be cutting in half the amount of land that we are using to provide for each person’s needs.