**44 billion t**

*max in 2020 if we are to avoid catastrophe*

In order to limit the rise in average global temperatures to 2 degrees Celsius by 2100, the UN-affiliated Emissions Gap Report of 2013 "recommends that emissions should reach a maximum of 44 gigatonnes of CO2 by 2020, falling to 40 gigatonnes by 2025 and further to 22 gigatonnes by 2050."^{1}

**40 billion t**

*max in 2025 if we are to avoid catastrophe*

**37 billion t**

*world total emissions in 2017*^{2}

**20 billion t**

*max in 2050 if we are to avoid catastrophe*

**20 t**

*annual average per American*^{3}

Includes 8.5 t due to government services when equally divided between all Americans. Another source says the the total is 16.4 t.^{4}

**7.56 t**

*flying SF to London business class nonstop round trip*^{5}

This uses a radiative forcing factor. Without radiative forcing, it's 4.00 t.

**4.9 t**

*annual average per human*

Assuming 7.5 billion humans in March 2018.^{6}

**4.41 t**

*annual gas consumption of my home*

Assuming 0.0061 t per therm for PG&E,^{7} and assuming that our gas usage in Feb 2018 was 50% more than monthly average. EPA suggests national average is 0.0053 t per therm.^{8}

**4.37 t**

*driving SF to FB HQ round trip by every weekday for a year*^{9}

28 MPG, 28 miles x 2. One trip is 0.017 t.

**2.61 t**

*flying SF to London economy class nonstop round trip*^{5}

This uses a radiative forcing factor. Without radiative forcing, it's 1.38 t.

**1.75 t**

*driving SFO to JFK round trip*^{9}

28 MPG, 2939 miles x 2

**1.35 t**

*annual electricity consumption of my home*

Assuming 0.0197 t per MWh for PG&E,^{10} and assuming that our electricity usage in Feb 2018 was equal to the monthly average. EPA suggests national average is 0.0744 t per MWh.^{8}

**1.15 t**

*flying SFO to JFK economy class nonstop round trip*^{5}

This uses a radiative forcing factor. Without radiative forcing, it's 0.61 t.

**0.52 t**

*eating 1 lb beef per week for a year*

Assuming 0.022 t per kg beef.^{11} Average American beef consumption was 1.07 lb per week in 2016.^{12}

**0.23 t**

*driving SF to Caltech round trip*^{9}

28 MPG, 387 miles x 2

**0.15 t**

*flying SFO to LAX economy class nonstop round trip*^{5}

This uses a radiative forcing factor. Without radiative forcing, it's 0.08 t.

**0.12 t**

*driving SF to Yosemite Valley round trip*^{9}

28 MPG, 194 miles x 2

**0.10 t**

*drinking 1/2 gallon cow milk per week for a year*

Assuming 0.001 t per kg milk.^{13} Re-calculating with numbers from a different source, total is 0.12 t to 0.15 t per year.^{14} Assumes 1 gallon of milk weighs 8.6 pounds.

**0.084 t**

*drinking 1/2 gallon soy milk per week for a year*

Well, calculating with numbers from source 14, the total is 0.079 t to 0.089 t per year.

**0.029 t**

*driving SF to San Jose round trip*^{9}

28 MPG, 48.5 x 2 miles

^{1}https://ourworld.unu.edu/en/carbon-emissions-must-be-cut-significantly-by-2020-says-un-report

^{2}https://news.nationalgeographic.com/2017/11/climate-change-carbon-emissions-rising-environment/

^{3}https://www.sciencedaily.com/releases/2008/04/080428120658.htm

^{4}https://calculator.carbonfootprint.com/calculator.aspx?tab=8

^{5}https://calculator.carbonfootprint.com/calculator.aspx?tab=3

^{6}https://www.census.gov/popclock/

^{7}https://www.pge.com/includes/docs/pdfs/about/environment/calculator/assumptions.pdf

^{8}https://www.epa.gov/energy/greenhouse-gases-equivalencies-calculator-calculations-and-references

^{9}https://calculator.carbonfootprint.com/calculator.aspx?tab=4

^{10}https://www.pge.com/en_US/about-pge/environment/what-we-are-doing/fighting-climate-change/fighting-climate-change.page

^{11}https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2535638/

^{12}https://www.usatoday.com/story/money/2017/07/03/americans-eat-more-beef-and-meat-trend-thats-expected-continue/435331001/

^{13}https://www.sciencedirect.com/science/article/pii/S002203021731069X

^{14}https://crueltyfreelife.wordpress.com/2013/06/14/sustainability-of-dairy-milk-vs-soy-milk/

Compiled by Aaron Gabriel Feldman in April 2018