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Visualizing the Flow of Energy-Related CO2 Emissions in the U.S.



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Visualizing the Flow of Energy-Related CO2 Emissions in the U.S.

Visualizing the Flow of Energy-Related CO2 Emissions in the U.S.

This was originally posted on the Decarbonization Channel. Subscribe to the free mailing list to be the first to see graphics related to decarbonization with a focus on the U.S. energy sector.

In 2021, U.S. carbon dioxide emissions from the generation and consumption of energy reached 4.9 billion tonnes.

To better understand how various energy sources and their end-uses contribute to carbon emissions, this graphic visualizes the flow of energy-related CO2 emissions in the U.S. using carbon flow charts by the Lawrence Livermore National Laboratory.

What are Energy-Related CO2 Emissions?

Energy-related CO2 emissions refer to the release of carbon dioxide as a result of the combustion of fuels to produce energy. They arise through the direct use of fossil fuels for transport, heating, or industrial needs, as well as the use of fossil fuels for electricity generation.

To provide some context, non-energy-related CO2 emissions are those that result from industrial chemical reactions, deforestation, and agricultural activities.

As the largest contributor to carbon emissions, however, energy-related CO2 emissions account for approximately 85% of all emissions in the U.S. which we will now explore in more detail.

U.S. Energy-Related CO2 Emissions in 2021

Followed by a pandemic-driven decline in 2020, energy-related carbon dioxide emissions in the U.S. increased by 325 million tonnes in 2021, marking the largest-ever annual increase.

Energy SourceCO2 emissions in million tonnes, 2021% of total energy-related emissions
Natural Gas1,63733.7%
Solar, Wind, Nuclear, Hydro, and Biomass00%

When we follow the CO2 emissions from the above fossil fuels to their end uses, transportation and electricity generation stand out as the biggest contributors.

In 2021, these two sectors accounted for more than 68% of all energy-related emissions in the country, roughly emitting 3.3 billion tonnes of CO2.

End-Uses CO2 emissions in million tonnes, 2021% of total energy-related emissions
Electricity Generation1,53731.6%
Industrial Uses96519.8%
Residential Uses3216.6%
Commercial Uses2394.9%

When it comes to transportation, petroleum accounted for 97% of emissions, largely due to motor gasoline and diesel consumption. On the other hand, coal and natural gas made up 99% of CO2 emissions related to electricity generation.

Due to its high carbon intensity, coal’s contribution to power sector emissions may also be of particular interest. As the share of coal rose from 20% to 23% in the U.S. electricity mix in 2021, electricity emissions from coal also increased for the first time since 2014.

Naturally, this shift raised the overall energy-related CO2 emissions in 2021. It also caused a 4% hike in the carbon intensity of the country’s electricity.

Lowering Emissions

To avoid the impacts of climate change, many countries and companies are working towards decarbonization across all sectors, which can largely be facilitated by reductions in energy-related carbon emissions.

Accounting for nearly 70% of all energy-related CO2 emissions, transportation and utilities can be important pillars in these efforts.

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Visualizing the Biomass of All the World’s Mammals

When the world’s biomass—the stuff we’re made of—is tallied up, humans and cattle outweigh wild mammals by a massive margin.



Visualizing the Biomass of All the World’s Mammals

Even as we understand more about the world we live in, certain aspects of it remain undefined or hard to comprehend.

One such example is in the scale and distribution of Earth’s life. What’s the ratio of wild to domesticated animals? How much do all of the world’s humans weigh?

Until recently, such questions were nearly unanswerable. A new report titled The Global Biomass of Wild Mammals helps shed more light on the composition and scale of life on our planet. The research provides an estimate of the biomass of all mammals, globally—including humans.

So, What is Biomass Anyway?

Biomass is simply the weight of living things.

In this study, researchers

created rough estimates for four major categories of mammals: humans, domesticated animals, and those that were found in wild terrestrial and marine environments. A further breakdown of mammal groups are found within each category.

To achieve this, they took the estimated number of species from census data and multiplied it with each species’ average body mass.

One component worth pointing out is that animals contribute very different amounts to the world’s biomass total. For example, whales significantly outweigh rodents in terms of biomass, even though there are fewer species and populations of whales. The fact that whales are so much larger than rodents means that even smaller populations can contribute a meaningful portion to overall biomass.

Mammalian Biomass, Organized Neatly

Each larger cube above represents 20 million metric tons of carbon, and the entirety of the visualization represents all living mammalian life on Earth.

The paper separates mammals into four distinct categories:

CategoryTotal Mass (Mt)Top Sub-Category
Domesticated Mammals651Cattle (416 Mt)
Wild Marine Mammals40Baleen Whales (23 Mt)
Wild Terrestrial Mammals24Even-Hoofed Mammals (11 Mt)

One of the most obvious takeaways from this data is that humans make up one-third of total mammalian biomass.

Perhaps even more strikingly, the animals we’ve domesticated for food, companionship, and labor make up close to 60% of the total weight of Earth’s mammals. Domesticated dogs and cats alone equal the total weight of all other wild land mammals combined.

The world’s sheep, on their own, weigh as much as all the whales and seals in the ocean. Domesticated buffalo such as the water buffalo, a species commonly found in Asia, combine to have the third largest biomass of all mammals.

Finally, there’s one category of mammal that comes way out on top.

Cattle Planet

The global livestock population has risen along with the human population, and cattle are now the top mammal in the world by weight.

In fact, just the United States’ share of cattle matches the biomass of all wild mammals on Earth.

As the standard of living continues to rise for people around the world, beef consumption has been increasing in many developing countries. Of course, raising cattle is a resource and land intensive operation, and there have been very real impacts on a global scale. For one, cows are a major source of methane emissions. As well, in Brazil, which accounts for around 25% of the world’s cattle population, pasture has directly replaced large swaths of rainforest habitat.

Waning Wildlife

At the very bottom of the visualization, dwarfed by humans and domesticated mammals, lies the vast array of wild mammals that live on planet Earth.

It’s sobering to see that the biomass of North America’s human population alone compares closely with that of all terrestrial wild mammals in the world. This includes plentiful creatures like rats and mice, as well as large mammals like elephants and bears.

Below are the top 10 wild mammalian contributors to biomass in the natural world.

RankContributorTotal Mass (Mt)Individuals (millions)
#1Fin Whales80.1
#2Sperm Whales70.4
#3Humpback Whales40.1
#4TAntarctic Minke Whales30.5
#4TBlue Whales30.05
#6White-Tailed Deer2.745
#7Crabeater Seals2.010
#8Wild Boar1.930
#9TAfrican Elephants1.30.5
#9TBryde's Whales1.30.1

In the ocean, whales and seals are the heavyweight champions. On land, deer, and boar come out on top as they are both heavy and plentiful.

Humans have a complicated relationship with large mammals. We feel a very clear connection to these creatures, and they are often the key figures in conservation efforts. That said, even small populations of humans have wiped out large mammal species in the past.

The news that cattle outweigh wild land animals by a factor of 20:1 is a reminder that human influence is perhaps even more powerful than we think.

The more we’re exposed to nature’s full splendor […] the more we might be tempted to imagine that nature is an endless and inexhaustible resource. In reality, the weight of all remaining wild land mammals is less than 10% of humanity’s combined weight. – Ron Milo, Professor of Systems Biology

Where does this data come from?

Source: The global biomass of wild mammals

Data notes: To come up with the numbers above, scientists estimated the total biomass of wild mammals on Earth by manually collecting population estimates for 392 land mammal species, which make up about 6% of all wild land mammal species, and using machine learning to infer the global populations of the remaining 94%. Their estimate includes 4,805 wild land mammal species out of approximately 6,400 known and extant wild land mammal species, excluding low-abundance species for which data are scarce.

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