Question

select the correct answer. an interglacial is a period of time that occurs between ice ages. its marked by warmer temperatures and milder climates. during previous interglacials, the co2 levels in the atmosphere were about 280 parts per million (ppm). in 2013, they were approximately 400 ppm. what is the percent increase in co2 between these two time periods? a. 33% b. 70% c. 43% d. 240%

Explanation:

Step1: Recall percentage - increase formula

The formula for percentage increase is $\text{Percentage Increase}=\frac{\text{New Value}-\text{Old Value}}{\text{Old Value}}\times100\%$.

Step2: Identify old and new values

The old value (CO₂ level in previous inter - glacial) is $280$ ppm and the new value (CO₂ level in 2013) is $400$ ppm.

Step3: Calculate the difference

$400 - 280=120$ ppm.

Step4: Calculate the percentage increase

$\text{Percentage Increase}=\frac{400 - 280}{280}\times100\%=\frac{120}{280}\times100\%$.
$\frac{120}{280}\times100\%=\frac{12000}{280}\approx42.86\%$. Rounding to the nearest percent, we get $43\%$.

Answer:

C. 43%