Counting Green

Isn’t it all a matter of multiplying a few factors together? This is a question that I am asked time and again as an environmental accountant, most recently in response to my work as Carbon Guru with ClimateClever developing an online carbon calculator for schools, homes and communities.

This question comes second to only to, “how is it possible for us to account for carbon emissions?” -the logic behind this question being that since emissions are invisible and intangible, how can they be counted?

My question in reply to these questions is, would we ask the same thing about accounting for money? Of course not. Accounting for money is at the centre of everything these days. But money is even more invisible and intangible than an emission — money exists mostly as electrons in computers these days, with very little embodied as cash in hand. Determining the value of money results from multiplying many factors together, all of which fluctuate geographically such as with currency exchange rates, or overtime such as through inflation. Nobody anywhere says accounting for money is easy.

So, let’s take a closer look at carbon accounting. Technically, we should use the term carbon dioxide equivalent global warming potential accounting, but this doesn’t roll off the tongue so easily. What this more exact term means is that we are potentially accounting for hundreds of different gases that contribute to trapping heat on the Earth. The most common of these gases are water vapour (H2O), however, water vapour drops out of the atmosphere as rain after only a short while. Since water doesn’t build up in the atmosphere it has minimal “global warming potential”, otherwise known as “radiative forcing”. By comparison, carbon dioxide (CO2), the most common greenhouse gas, stays in the atmosphere for as much as 500 years! In the same way that we might convert other currencies into Australian dollars to add up the coins in our piggy bank here, in carbon accounting we add up the global warming potential of all these gases in terms of the amount of carbon dioxide (CO2) that would be needed produce the same amount of global warming. Just like currency exchange rates, scientific understanding of the global warming potential of these gases changes, and so these factors must be updated according to the latest science.

There are many other issues to consider. For example, the easiest emissions to account for are those that we directly cause by ourselves (named Scope 1 emissions), such as burning a litre of petrol. This is an example of the most straightforward calculation, mainly using a factor estimated from the average number of carbon atoms in that volume of petrol. But even here there are options — since older vehicles or motors such as in generators, do not combust as efficiently as in newer cars resulting in more polluting methane and nitrous oxide gases. (These factors also differ between countries with different petrol fuel standards and different climates — in Australia our petrol is on average purer and warmer/less dense than in the United States).

From here on things get much, much more difficult. Take carbon emissions resulting from the use of electricity from the grid. These emissions happen far away from us (named Scope 2 emissions) and depend upon whether the mix of sources of electricity in each grid contains more-or-less coal, other fuels, and renewables. Separately accounted for is the average loss of electricity in wires and other equipment required to deliver it. The government supplied factors for these grids converting electricity into carbon emissions also change from year to year, sometimes abruptly such as the reduction of factors this year for the grid in South Australia resulting from a large boost of renewables and the Tesla big battery. The same holds true for carbon emissions in different water and sewer networks. At Climate Clever we also use computer mapping (Geographic Information Systems) to check which grids or water schemes apply to a school’s location. These network configurations also change from year-to-year. Creating systems to track all this is a big job, especially while still making them easy and fun enough for schools and kids to use them!

At the end of the day, while Climate Clever has managed to tackle many of these tough issues of carbon accounting to make them accurate but easy to use, carbon accounting is quite a bit more difficult than “multiplying a few factors together.” And don’t let me get started on much more complicated carbon accounting problems involved in school tree plantings and student transportation to school! Actually, we’ve already started on solving these problems, so stay tuned for my later blog post on these when we release an updated version of the ClimateClever app next year.

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