getting your numbers straight.

14 Aug

Images of different foods and forms of transportation on a black board with calculations written on them.

what’s in it for you?

One-stop shop to look up essential GHG emissions data

Decide on what activities you could personally save on

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Numbers. <3. 
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5-7 minute read

the last century of emissions.

Bar chart showing emissions climb from 10Gt in 1921 to 55Gt in 2021 in 25 year intervals — **Fig 1.** Global Greenhouse Gas (GHG) emissions (2021) in CO2e Gigatonnes (Gt) = 1,000,000,000 tonnes.

Essential for your basic knowledge on climate: total global GHG emissions are over 50Gt [1].

GHG = CO2?

**Fig 2.** Total GHG emissions at a 3:1 ratio of Carbon Dioxide (CO2) to other GHG emissions

Different GHGs have a different global warming potential based on their chemical interactions in the atmosphere [1, 2]. To make them comparable and be able to summarise them in a total emissions number that is relevant for climate change, the unit of CO2 equivalent (CO2e) has been established. For example, methane (CH4) has 28-times the global warming potential of Carbon Dioxide (CO2) on a 100-year timescale, meaning that 1t of CH4 translates into 28t of CO2e. On a 20-year timescale, methane is even 80-times more potent than CO2 - which could make one question whether the 100-year timescale is the right benchmark given the urgency on climate action [3].

With CO2 making up roughly ¾ of total global GHG emissions, encountering a number for emissions around 35-40Gt will refer to carbon emissions, resulting predominately from burning fossil fuels. When you see a number above 50Gt, generally all GHG emissions are being addressed, including sources such as methane emissions from livestock or land use change [1].

counting heads.

Bar chart comparing avg. GHG emissions globally with 5 selected countries — **Fig 3.** Average GHG emissions per capita (2021) - global and exemplary countries from different continents, GDP levels, and noticeably high or low per-capita emissions to showcase the spectrum.

By dividing total GHG emissions through a respective reference population, one can derive GHG emissions per capita. Hence, dividing the total global emissions of ~55Gt through our global population of ~8 billion people results in an average of ~7t of emissions per capita - simple, right?

While being a relevant and interesting index, one must not mistake these numbers for a personal carbon footprint; with a large share of emissions coming from industrial production processes, military efforts, etc., simply breaking these total emissions down to an average individual would be very misleading as their daily activities do not produce those emissions. Therefore, a country like Saudi Arabia, the world’s second largest oil producer, can have very high per capita emissions despite the lifestyle of the majority of citizens being far from directly producing such levels of emissions [4]. Let’s look at some daily activities that we generally do have more direct control over.

switching the english channel.

Comparing emissions of going from London to Paris with a fast moving train on left side of the image and a plan being boarded during sunset on the right half — **Fig 4.** Train vs. plane: (conservative) average GHG emission estimates going from London to Paris compared.

Big Ben and the Eiffel Tower are only ~350km apart. Nice little fact - but perhaps even more interestingly, you could take the Eurostar train 14-times before hitting the same emissions flying over just once [5]. And on average even have your first bite of a fresh croissant 30 minutes faster.

high steaks.

Comparing emissions of eating a 250g steak with an image of Tofu shown on the left half and a beef steak on the right — **Fig 5.** Tofu vs. beef: average GHG emissions of a 250g “steak” compared.

What a multiple to raise the steaks; 1kg of meat from beef herd cattle has a carbon footprint of ~100kg CO2e, 1kg of tofu carries around 3kg of CO2e - so a 100:3 ratio [6]. Okay, tofu (depending on its firmness level) only has 1000-1500 kcal/kg while beef yields roughly double at ~2500kcal/kg - so let’s make it 100:6. And you can keep the extra protein that the tofu brings for free!

What are some emission numbers that you are curious about? Let us know in the comments!

our two cents

Emissions are what drives climate change and should form the foundation of any plan of action or active discourse on the topic. Having a fundamental understanding of where emissions come from as well as a being able to ballpark their sources is therefore a crucial skill. We hope this article adds some meaningful and inspiring numbers to your climate-knowledge toolbelt that you can now always come back to.

[1] Ritchie, Hannah. “CO₂ and Greenhouse Gas Emissions.” Our World in Data, May 11, 2020. https://ourworldindata.org/greenhouse-gas-emissions.
[2] IPCC. “Figure: SPM.1,” n.d. https://www.ipcc.ch/report/ar6/wg3/figures/summary-for-policymakers/figure-spm-1/.
[3] MIT Climate Portal. “Why Do We Compare Methane to Carbon Dioxide over a 100-Year Timeframe? Are We Underrating the Importance of Methane Emissions? | MIT Climate Portal,” n.d. https://climate.mit.edu/ask-mit/why-do-we-compare-methane-carbon-dioxide-over-100-year-timeframe-are-we-underrating.
[4] Owen-Burge, Charlotte. “Race to Zero Builds Momentum - Climate Champions.” Climate Champions, August 17, 2021. https://climatechampions.unfccc.int/the-race-to-zero-is-on/.
[5] Eurostar. “All about Emissions,” n.d. https://www.eurostar.com/rw-en/carbon-footprint.
[6] Statista. “Average GHG Emissions of Various Major Food Products per Kilogram Worldwide,” February 6, 2023. https://www.statista.com/statistics/1201677/greenhouse-gas-emissions-of-major-food-products/#:~:text=Food%20emissions%20vary%20greatly%20depending,les%20than%2010%20kg%20CO2eq.

sascha brumm

Sascha is our environmental psychologist. After studying in Germany, the UK, and Japan, he worked for the UN Office for Sustainable Development in South Korea before moving into management consulting at BCG where he focused on climate and sustainability projects in the energy, chemicals, and public sector. Now he has moved to Tokyo to find and evaluate the true value of food as part of his PhD research at the United Nations University and University of Tokyo. Sascha is your guy for asset evaluation and management—unless it’s within the actual financial market. Better to ask him for vegan recipes instead.