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50 Years to Net-Zero


A country wishes to achieve net-zero CO2 emissions in 50 years. 

At the start of the program their emissions are 800MtCO2 year-1. 

They decide that they will be able to reduce their emissions at a stable rate so that each subsequent year they emit 12MtCO2 less than the previous year.

a) Calculate the total emissions that the country had produced over the 50 years, giving your answer in MtCO2.

[2 marks]

b) Show that a graph of MtCO2 produced per year against the year follows a straight line with equation:

\[y = 800 – 12x\]

[1 mark]

At the same time as reducing their emissions, the country decides to start a carbon dioxide removal program, whereby a certain amount of carbon dioxide is captured from the atmosphere and sequestered underground each year. 

The program begins in the tenth year. 

When the graph of MtCO2 removed per year is plotted against the year, it follows the curve with equation

\[y = 0.1x^{2} – x\]

c) Determine whether the country achieves their goal by finding the year in which the emissions removed are equal to the emissions produced, and thus the net emissions from the country are zero.

[3 marks]

After the 50 year program, the countries emissions stabilise at the final value. 

The MtCO2 absorbed per year follows the same trend as before. 

The country wishes to have not contributed to global warming at all since the start of the program. To achieve this, their net total CO2 emissions over the entire program would have to be zero.

d) Given the above information, by using calculus show that it takes 109 years for the country to have had a net zero effect on global warming since the start of the study.

[5 marks]

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