Impact of food choices on CO2 emission and deforestation.nlogo

breed [trees tree]
breed [CO2s CO2]     ;; packets of carbon dioxide

globals [population foodproduction initial-foodproduction foodconsumption meat-foodproduction crop-foodproduction populationconsumption foodsecurity]



to setup-omnivore
  clear-all
  setup-patches-omnivore
  set population 7.5
  set population-growth-rate 1
  set Food-security-mitigation "crops and livestocks"
  reset-ticks
end

to setup-plant-based
  clear-all
  setup-patches-plant-based
  set population 7.5
  set population-growth-rate 1
  set Food-security-mitigation "crops"
  reset-ticks
end


to go

  population-growth                    ;; growth of world population
  food-production                      ;; food produced from farmed animal and plants
  population-food-consumption          ;; food consumed by the world population
  food-security                        ;; difference between food produced and consumed
  deforestation                        ;; increasing food production by replacing forest by crops
  move-CO2                             ;; moving CO2 molecules
  carbondioxide-emission               ;; CO2 emission
  CO2-sink                             ;; CO2 absorbtion by the forest

  tick
  if (ticks = 150) [stop]
end


to deforestation
  ;; replacing 5 patches of forest by crops and livetocks when foodsecurity is not sufficient (not enough food produced)
  if Food-security-mitigation = "crops and livestocks" [
    ask n-of 3 patches with [pcolor = brown]
    [if (foodproduction - populationconsumption) < 0
      [
        ask n-of 1 patches with [pcolor = brown ]
        [
          set pcolor 47
          sprout 10 ;; crop farming intensification (monoculture)
          [
            set color 63
            set shape "plant"
            set size 0.8
            set crop-foodproduction 1
          ]
        ]

        ask n-of 2 patches with [pcolor = brown]
        [if (foodproduction - populationconsumption) < 0
          [
            ask n-of 1 patches with [pcolor = brown ]
            [
              set pcolor green
              sprout 10 ;; lifestock farming intensification
              [
                set color 8
                set shape "sheep"
                set size 0.8
                set meat-foodproduction 1
              ]
            ]

          ]
        ]
      ]
    ]
  ]


  ;; replacing 5 patches of forest by crop lands when foodsecurity is not sufficient (not enough food produced)
  if Food-security-mitigation = "crops" [
    ask n-of 5 patches with [pcolor = brown]
    [if (foodproduction - populationconsumption) < 0
      [
        ask n-of 1 patches with [pcolor = brown ]
        [
          set pcolor 47
          sprout 10 ;; crop farming intensification (monoculture)
          [
            set color 63
            set shape "plant"
            set size 0.8
            set crop-foodproduction 1
          ]
        ]

      ]
    ]
  ]
  ;; removing tree turtle
  ask turtles with [shape = "tree"][if pcolor = 47 [die]]
  ask turtles with [shape = "tree"][if pcolor = green [die]]

end


to carbondioxide-emission ;; Co2 emission caused by animal farming and crop farming
  ask patches with [ pcolor = green]  [sprout  2 [ set size 0.5 set shape "carbondioxide" set color red ]]
  ask patches with [ pcolor = 47 ] [sprout 1 [ set size 0.5 set shape "carbondioxide" set color red ]]
end


to population-growth ;; population growth rate
  set population (population + population * (population-growth-rate / 100))
end

to food-production ;; food produced from livestocks and plants
  set foodproduction (foodproduction + ((meat-foodproduction * (count turtles with [shape = "sheep"])) + (crop-foodproduction * (count turtles with [shape = "plant"]))))
end


to population-food-consumption ;; food consumed by the word population
  set populationconsumption (populationconsumption + (population * 85))
end

to food-security
  set foodsecurity (foodproduction - populationconsumption)
end




to setup-patches-omnivore
 ask patches [
    set pcolor one-of [green brown 47]
]

  ask patches with [pcolor = brown ]
 [
    sprout 1 [
      set shape "tree"
      set color green
    ]
  ]

  ask patches with [pcolor = green ]
  [
    sprout 1 [
      set color white
      set shape "sheep"
      set size 0.8
      set meat-foodproduction 1
    ]
  ]

   ask patches with [pcolor = 47 ]
    [
        sprout 1 [
      set shape "plant"
      set color 64
        set size 0.7
      set crop-foodproduction 1
    ]
  ]

end

to setup-patches-plant-based
 ask patches [
    set pcolor one-of [ brown 47]
]

  ask patches with [pcolor = brown ]
 [
    sprout 1 [
      set shape "tree"
      set color green
    ]
  ]


   ask patches with [pcolor = 47 ]
    [
        sprout 1 [
      set shape "plant"
      set color 64
        set size 0.7
      set crop-foodproduction 1
    ]
  ]

end

to setup-CO2
  set-default-shape CO2s "carbondioxide"
   ask CO2s [
    set color red
    setxy random-xcor random-ycor
  ]
end


to move-CO2
  ask turtles with [shape = "carbondioxide"] [
    rt random 52 - 19 ;; turn a bit
    let dist 0.05 + random-float 0.1
     fd dist
   ]
end

to CO2-sink
  ask turtles with [shape = "carbondioxide"][if pcolor = brown [die]]
end

to hide-CO2 ;; Hiding CO2 molecules can improve the speed of the model
  ask turtles with [shape = "carbondioxide"]  [ hide-turtle ]
end
@#$#@#$#@
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"Crop" 1.0 0 -987046 true "" "plot count turtles with [shape = \"plant\"]"
"Farmed animals" 1.0 0 -16448764 true "" "plot count turtles with [shape = \"sheep\"]"

BUTTON
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@#$#@#$#@
## WHAT IS IT?

This model attempts to demonstrate the impact of the food diet choices on carbon dioxide emissions (CO<sub>2</sub>) and deforestation.

The model focuses on the two senarios: a world with people having a standard omnivore diet and a world with people feeding exclusively on a plant-based diet.


## HOW IT WORKS
The model creates an initial land structure composed of forest, farming crop land, and farming livestock (for omnivore diet only).

Crops and livestock produce food and emit carbon dioxide (CO<sub>2</sub>s) onto the atmosphere. 

The CO<sub>2</sub>s travels in either direction. 

Forests capture the CO<sub>2</sub>s. 

The human population is initialised at 7.5M individuals. The population grows according to time and they consume food. 

We track the food security, which is the difference between the quantity of food produced by the land and the quantity of food consumed by the population. 

If the value of food security is negative the deforestation occurs and the forest is replaced by farming crops and livestock.




## HOW TO USE IT
**Setting up initial map**
This model can be initialised by clicking one one of the two buttons:
	- 'setup-omnivore': this will setup forest, livestock farmed land and crop land.
	- 'setup-plant-based' : this will setup forest and crop land. 


**go**
starts and stops the simulation.


**Hide CO2**
If the model slows down, you can click on 'Hide CO2', this will hide the CO2s molecules and make the model faster.

**population-growth-rate**
Sets the growth rate of the word population.

**Food-security-migitation**
Selects by which source of food will be produced from the deforestation. 
The forest can be replaced by crops only or by crops and livestock.

## THINGS TO NOTICE

- Both omnivore diet and plant based diet lead to deforestation. However the speed of the deforestation on an omnivore diet faster.

- A plant based diet leads less CO2 released onto the atmosphere 




## THINGS TO TRY

1. Running the model initialising the land based on a plant-based diet and omnivore diet

2. Changing the population growth rate

3. Selecting the forest will be replaced by crops or crops and livestock to sustain food availability



## EXTENDING THE MODEL


These are some of the ways to extend this model further: 

- Add land where there is no forest and no farming is possible, with a more accurate representation of the land distribution
- Make livestock consume crops
- Set up an accurate food quantity produced based on calories for meat and crops
- Set up an accurate green of gas emission for livestock and crops 
- Set up an accurate carbon sink by the forest
- Set up and accurate food quantity consumed based on calories
- Add a slider allowing to select the average quantity of animal product consumed per week



## CREDITS AND REFERENCES

If you mention this model or the NetLogo software in a publication, we ask that you include the citations below.

For the model itself:

 * Kouidri, A.. NetLogo Climate Change model. Impact of food choices on CO2 emission and deforestation.   Data ScienceTech Institute (DSTI), France.

Please cite the NetLogo software as:

* Wilensky, U. (1999). NetLogo. http://ccl.northwestern.edu/netlogo/. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.




## COPYRIGHT AND LICENSE


Copyright 2022 Allan Kouidri.


![CC BY-NC-SA 4.0](http://ccl.northwestern.edu/images/creativecommons/byncsa.png)

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.


To view a copy of this license, visit https://creativecommons.org/licenses/by-nc-sa/4.0/ or send a letter to Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA.


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