Daniel Bachler / Sep 29 2019
Remix of

# Climate change calculations

This notebook is a collection of calculations for my blog post "My thoughts on fighting climate change effectively". It uses the wonderful nextjournal notebook system - if you would like to play with these calculations, just create an account and remix the notebook.

```using Unitful
using Unitful: km, m
using Unitful:Mg,kg,g
using Unitful:l
using Unitful:W,kW,MW,GW,TW
using Unitful:h

# define currency as dimension, euro as unit
@dimension C "C" Currency
@refunit € "€" Euro C false```

## Driving distance until a ton of CO2 is emitted

How far can an average car drive until it has emitted a ton of CO2? We use 130g/km for the average car as per https://ec.europa.eu/clima/policies/transport/vehicles/cars_en

```averageCarCo2EmissiongPerKm = 130g/km
kmDrivenWithTill1TonCo2 = 1Mg/averageCarCo2EmissiongPerKm # 1 ton = 1 Megagram
uconvert(u"km",kmDrivenWithTill1TonCo2)```
7692.31 km

### German petrol pricing seen as a carbon tax

What is the current price of a ton of CO2 for driving this distance with a car given the level of taxation of petrol in Germany of 0,65€/l (https://www.avd.de/kraftstoff/staatlicher-anteil-an-den-krafstoffkosten/)

```energyTaxPerLiterPetrol = 0.65€/l
petrolUsePer100km = 5.9l/100km
kmPerLitre = 1 / petrolUsePer100km
litresPetrolForOneTonOfCo2 = kmDrivenWithTill1TonCo2 / kmPerLitre
priceForOneTonOfCo2AtCurrentPetrolPrices = litresPetrolForOneTonOfCo2 * energyTaxPerLiterPetrol
uconvert(€,priceForOneTonOfCo2AtCurrentPetrolPrices)```
295.0 €

WOW! I thought I had an error somewhere when I saw this but it's in line with the information about the income from the Mineralölsteuer here: https://www.welt.de/wirtschaft/article173181909/Mineraloelsteuer-Einnahmen-auf-hoechstem-Stand-seit-14-Jahren.html

What would be the amount of tax paid for a litre of petrol if co2 emissions were priced at 50 €/ton of CO2?

```pricePerLitre = 50€ / litresPetrolForOneTonOfCo2
uconvert(€/l,pricePerLitre)```
0.110169 € L^-1

11 cents per litre - quite a bit lower than what is currently in place

Given the total tax windfall of the German Mineralölsteuer is 42 billion Euro and German CO2 emissions are 0,8 Gigatons, what is the current average taxation of a ton of CO2?

```# calculate taxlevel per kg co2 for germany
totalTaxWindfallGermanEnergyTax = 42_000_000_000€
Co2EmissionsGermany = 800_000_000_000kg
pricePerTon = totalTaxWindfallGermanEnergyTax/Co2EmissionsGermany
uconvert(€/Mg, pricePerTon)```
52.5 € Mg^-1

## Introducing a carbon tax in the US

For a country like the US, what would the per capita payout look like if a CO2 tax were introduced with flat per capita payout of the revenue?

```# calculate tax payout for us per capita given current emissions
usPopulation = 320_000_000
usCo2EmissionsPerYear = 5_300_000_000_000kg
taxPerTonCo2 = 50€/1Mg
taxRevenue=usCo2EmissionsPerYear*taxPerTonCo2
taxPayoutPerCapity=taxRevenue/usPopulation
uconvert(€,taxPayoutPerCapity)```
828.125 €

Total tax revenue for this case in Billion Euro

`uconvert(€,taxRevenue/1_000_000_000)`
265.0 €

## Planting trees as carbon sinks

How big a planting area would be needed if we plant some of the most efficiently carbon captoring trees, Empress trees? https://www.bloomberg.com/news/features/2019-08-02/we-already-have-the-world-s-most-efficient-carbon-capture-technology Here we calculate the planting area to get negative annual emissions of 2Gigatons of CO2

```# How big an Empress tree planting area would be needed to offset 2Gton CO2?
oneAcreInm2 = 4000m^2
kgCo2PerAcrePerYear = 100000kg/oneAcreInm2
negativeEmissions=2_000_000_000_000kg
areaNeeded=negativeEmissions/kgCo2PerAcrePerYear
uconvert(km^2,areaNeeded)```
80000.0 km^2

Comparing this to the wikipedia list of countries, this is an area about the size of Cyprus