The approximate increase in atmospheric carbon dioxide over the last 250 years is about what percent?

The approximate increase in atmospheric carbon dioxide over the last 250 years is about what percent?

• A. 5%
• B. 25%
• C. 50%
• D. 75%

Answer: (B)

The main idea is to compare how much atmospheric CO2 has risen from pre-industrial times and express that change as a percentage. Pre-industrial CO2 was about 280 parts per million (ppm). Today it’s about 420 ppm. The increase is roughly 140 ppm. To find the percent increase, divide the increase by the original amount: 140 ÷ 280 ≈ 0.50, which is about 50%. Using a slightly lower current value, like 410 ppm, gives 130 ÷ 280 ≈ 0.46, about 46%. So the approximate rise is around 45–50%, closer to half than to 25% or 75%. This reflects the substantial, human-caused increase in CO2 over the industrial era.

The main idea is to compare how much atmospheric CO2 has risen from pre-industrial times and express that change as a percentage. Pre-industrial CO2 was about 280 parts per million (ppm). Today it’s about 420 ppm. The increase is roughly 140 ppm. To find the percent increase, divide the increase by the original amount: 140 ÷ 280 ≈ 0.50, which is about 50%. Using a slightly lower current value, like 410 ppm, gives 130 ÷ 280 ≈ 0.46, about 46%. So the approximate rise is around 45–50%, closer to half than to 25% or 75%.

This reflects the substantial, human-caused increase in CO2 over the industrial era.