SME
Grade 6 Science · Earth & Space Science
Earth's changing climate
Use this for “Carbon dioxide is 340 ppm and rises 2 ppm a year. What will it be in 40 years?”
Chart
Years: 40 years
Carbon dioxide after: 420 ppm
Carbon dioxide at the start: 340 ppm
Rise each year: 2 ppm/yr
Total rise: 80 ppm
This is an example. Type your own values to start a new problem.
r (ppm/yr)
×
y (years)
=
c (ppm)
s (ppm)
+
c (ppm)
=
f (ppm)
Formulas
2 × 40 = 80
Rise each year × years = total rise
340 + 80 = 420
Carbon dioxide at the start + total rise = carbon dioxide after
Assumptions
•
Carbon dioxide in the air is measured in parts per million (ppm): how many of every million bits of air.
•
Before factories it was about 280 ppm. Burning fuels adds more each year, and more carbon dioxide traps more heat.
•
The yearly rise has grown: about 1 ppm a year in 1960, about 2.5 ppm a year now.
•
The real yearly rise has grown, so a steady rise gives a low estimate for many years ahead.
Step-by-step
WE KNOW
Carbon dioxide at the start: 340 ppm
Rise each year: 2 ppm/yr
Years: 40 years
FIND
total rise, carbon dioxide after
Step 1 · Find total rise
2 × 40 = ?
Rise each year × years = total rise
The same rise every year, so multiply by the years.
Total rise = 80 ppm
Step 2 · Find carbon dioxide after
340 + 80 = ?
Carbon dioxide at the start + total rise = carbon dioxide after
Add the rise to the starting amount.
Carbon dioxide after = 420 ppm
Check
Put the numbers back in. Both sides should match.
2 × 40 = 80 ✓
340 + 80 = 420 ✓
Topic check
See what you know: 5 questions on this topic
New questions each time. Pass to mark it complete.