Concentrations are Calculated, Emissions are Estimated

For the past two years, CO2 emissions have not risen globally. Hooray for us and our restraint!

Despite this, the concentrations of CO2 in the atmosphere rose dramatically. “It was the fourth year in a row that carbon dioxide concentrations grew by more than 2 parts per million, with an annual growth rate of 3.05 parts per million in 2015.”

Why?

Was it El Niño? Umm, no… “Writing in the April 15 issue of Nature, Feely and his colleagues suggest that the findings, based on direct measurements in the equatorial Pacific from 1992-1996, indicate that during the strong El Niño events, the release rate of CO2 from the ocean to the atmosphere was reduced to 30-80% of that of normal non-El Niño periods. This decline in carbon dioxide release from the sea to the air is large enough to be seen as a CO2 anomaly in the atmosphere.”

Did we burn down a lot more forests? Umm, no… “the rate of net global deforestation has slowed down by more than 50 per cent, the United Nations Food and Agriculture Organization (FAO) said in a report.”

Maybe it’s industrialization in China? Umm, no, “China’s economy slowed in December, capping the weakest quarter of growth since the 2009 global recession, as the Communist leadership grapples with a transition to consumer-led expansion. Industrial production, retail sales and fixed-asset investment all slowed at the end of the year”

So why did concentrations rise dramatically in a year when emissions stayed the same?

It’s quite possibly because emissions didn’t in fact stay the same, sadly enough.

We can accurately measure the concentrations of greenhouse gases in the atmosphere. Once they are emitted, they mix with the rest of the atmosphere fairly quickly and it’s pretty easy to measure.

However, there aren’t any CO2 meters attached to smokestacks, cars, rice paddies, digesting cows and other sources of greenhouse gases. Our emissions aren’t measured, they’re estimated.

Here’s how Carbon Fund does it: “Carbonfund.org’s Carbon Calculators use information from the U.S. Department of Energy’s Energy Information Administration, the Environmental Protection Agency, and other leading sources to develop an accurate assessment of carbon dioxide emissions emitted per energy type or use.

…”We calculate emissions from electricity generation based off figures from the EPA’s eGRID emission factors based on 2009 and 2012 data. On average, electricity sources emit 1.222lbs CO₂ per kWh (0.0005925 metric tons CO₂ per kWh). State CO₂ emissions per kWh may vary greatly in accordance with the amount of clean energy in the energy supply (Vermont: 0.0055 lbs/kWh; North Dakota: 2.0685 lbs/kWh).”

…”The average person’s diet contributes 2,545 kilograms CO₂e to the atmosphere each year. By dividing by 365, it is deduced that the average person’s diet contributes, on average, 7 kg CO₂e a day from their meals.”

Are you starting to get the picture? On that web page alone, the word ‘average’ occurs 21 times.

How about the EU? Well, they have a published document with a title that says it all: “European Union CO2 Emissions: Different Accounting Perspectives.” In their Executive Summary the subhead titled “Different Data Gives Different Results” we read, “However, before using these perspectives in a complementary manner, users should be aware of some issues. These three perspectives are all based on different datasets. These datasets use different ‘system boundaries’ (the type of information that is included) and calculation methods. They also vary in terms of the quality of data they use. These differences in underlying methods and input data affect the resulting emissions calculations. Some results therefore have a percentage of ‘uncertainty’ attached to them that reflects the gaps that exist in the data they are based upon. This in turn has an effect on how applicable some of the resulting data is to policymakers.”

The University of Cambridge in England has a webpage called “The Naked Scientists.” When visitor Jenny Boyd asked “How do countries measure their carbon dioxide emissions?” the Naked Scientists asked for help, bringing in Gregg Marland at the Environmental Sciences division, Oakridge National Laboratory in the U.S.

He said, “Actually, I think there’s a misconception that CO₂ emissions are measured.  What you try to do is to measure how much fuel is burned and if you know how much carbon is in the fuel, you can calculate how much CO₂ must be produced, and very seldom is that, in fact, measured.” …”For countries like those in the EU or the US or Japan, my guess is that the error margin is something in the order of plus or minus 5%.  For those discharging smaller quantities of CO₂, the error bars, I think can be as high as 20 to 25% and there are some very large countries – in China, we’ve actually published the estimate that they are maybe as large as 15 or 20%.”

“China, the world’s leading emitter of greenhouse gases from coal, has been burning up to 17 percent more coal a year than the government previously disclosed, according to newly released data.” This was reported in November of 2015.

Maybe that margin of error should be a bit more than 20%. In fact, it looks like what we are celebrating is not a flat lining of emissions. It’s more like ‘the stuff we were able to measure last year didn’t go up this year.’ Which is… nice, but not quite the same thing.

Concentrations are not expected to rise exactly at the same time as emissions. The various carbon sinks work at their own rhythm and they draw down CO2 at different times of the year. As Freeman Dyson has noted, we don’t really know too much about how the five major carbon sinks interact with the rest of the complicated climate system. So we don’t know if the striking rise in concentrations is in response to something we’re doing now or something we did ten or twenty years ago.

But it’s kind of funny that in a world where policy makers are constantly talking about capping emissions, they don’t really know what emission levels are.

Which is one more argument in favor of my preferred policy option, a small carbon tax leveled at production source, balanced by a rebate of equal size to citizens.