Fighting climate change starts with numbers: tracking how much carbon we are emitting

The earth is in the throes of a climate crisis and many local governments want to do their part in saving the planet. But first, they have to measure the carbon they need to stop emitting.

Washington, DC, for instance, has agreed to reach “carbon neutrality” by 2050. That means that it must emit far less carbon than it does now, instead generating most energy from renewable sources; for the small amount of carbon it still does emit, there need to be enough trees or other methods to absorb the carbon.

DC produced 7.3 million metric tons of greenhouse gas in 2017. Besides moving that to a net of zero by 2050, DC plans to use 100% renewable energy sources and cut 50% of its greenhouse gas emissions by 2032.

Maryland has also pledged to reach 50% renewable energy by 2030, and the small city of Takoma Park resolved to become fully net zero as early as 2035.

The first step is tracking how much carbon is being emitted. That’s not as easy as it sounds.

How do cities measure their emissions?

The Greenhouse Gas Protocol is a standard guide for measuring carbon emissions for cities.

It asks cities to measure their greenhouse gases in five categories:

• Stationary energy, which in urban areas is mostly buildings. Houses, offices, and schools (when not shut down for coronavirus), hospitals, factories, and all other kinds of things happening in a certain place use some energy. In DC, that makes up 74% of energy.
• Transportation, including cars, buses, trains, airplanes, boats, etc. For DC, 25% of emissions are transportation.
• Waste treatment, like disposal of trash, incineration, or water treatment. Besides just the fact that these use energy, such processes can emit their own greenhouse gases directly.
• Industrial processes and product use: These are greenhouse gases that come from furnaces or chemical processes in manufacturing items, or when people use refrigerants, aerosols, etc. that release gases into the air.
• Agriculture, forestry, and other land use (AFOLU): This is kind of a general area of things that are really hard to measure. It includes livestock, um, emitting methane out the rear end (and front) from their digestive process. It includes when forests are cut down for development and thereby stop absorbing carbon. And lots more.

Along with many other cities, DC has signed onto the Greenhouse Gas Protocol, meaning it will use this accounting system for tracking its own emissions.

Not all emissions are inside borders

Energy flows across a grid, and so just looking at greenhouse gases emitted into one city or state’s air doesn’t tell the whole story. For instance, if a building uses a lot of electricity that comes from a coal power plant two states away, the building occupants are still the cause of those carbon emissions. If a city ships waste away to be treated or burned, the same applies.

The protocol covers some of this. Besides measuring emissions locally, it includes “energy generation supplied to the grid” as well as treatment, burning, etc. of waste outside.

But this still doesn’t measure all emissions. Rick Heede, the co-founder and director of the Climate Accountability Institute, a research non-profit dedicated to promoting and understanding the ways in which carbon emissions affect the climate, says there are many ways individuals contribute to the buildup of carbon in the atmosphere that cities cannot reasonably keep track of.

“Things that are often ignored are international shipping, or trucking or freight servicing the residents … or the businesses,” he said.

By this, he means the complex network of freight transport that services the economy: the cargo planes which land outside cities (here, that’s in places like Baltimore or Dulles Airport), the fleets of FedEx and UPS vehicles that snake their way in and out of cities to service Amazon and other online shopping deliveries. It’s unlikely the city will be able to account for all the emissions of such activities.

Inventories such as the Greenhouse Gas Protocol focus on emissions that take place within the territorial boundaries of a city or state. But Heede says, “I don’t know of any inventories that account for nationwide freight or a proportion of nationwide freight allocated” to residents of a city.

Also unmeasured are the carbon emissions that come from individual red-meat or dairy consumption. According to the UN’s Food and Agricultural Organization, this is a “significant contributor to global human-induced GHG emissions,” spewing out 8.2 gigatonnes of carbon into the atmosphere in 2010, with overall emissions growing 18% from 2005 to 2015. For scale, one gigatonne is equal to one billion tons.

Then there’s the industry behind food production and processing, most of which takes place outside the city’s boundaries, but releases carbon into the atmosphere — not just through farming, but in their complex manufacturing processes.

Cities aren’t measuring some of this because it’s very hard

City environmental officials are well aware of these holes, and so is the Greenhouse Gas Protocol, which has a sixth category: “Any other emissions occurring outside the geographic boundary as a result of city activities. These emissions are not covered in this version of the GPC but may be reported separately.”

The main problem is there’s not a good way to calculate these numbers. Therefore, Heede said, cities focus more on the emissions they can measure and control. After all, they have plenty of work ahead just to reduce those easily-measured emissions, so while it’s a problem to miss some, it’s not the top challenge right now.

As Heede explained, “the city has very, very little influence on how a farmer manages methane and waste on a dairy farm that makes milk.” But, he added, people can also do their part by being conscious of the impact of their own decisions. That includes simple lifestyle changes such as reducing red meat consumption, recycling, and buying local when you have the means to do so, he said.

And as Heede points out, because of the way “net-zero” has been defined, these “other ways of reducing global emissions might not even affect our net-zero goal in 2050,” but still have a profound impact on the global environment and our future as a species living on this planet.