What was the global average concentration of carbon dioxide in the atmosphere in 2024?
Answer422.8 parts per million
At Mauna Loa, Hawaii, the monthly average reached 427.55 ppm in August 2026.
Source: NOAA Climate.gov (2024) climate.gov
Science · Facts & sources
Carbon facts & stats
5 sourced facts about carbon dioxide and carbon emissions, each with the context behind the number. 4 more are in today's round and appear here after it closes.
The basics
About how much carbon dioxide does a typical U.S. passenger car emit per year?
Answerabout 4.6 metric tons
EPA assumes about 22.2 miles per gallon and around 11,500 miles driven per year.
Source: U.S. Environmental Protection Agency epa.gov
Going deeper
When was the last time Earth's atmospheric CO2 was as high as it is today?
Answerroughly 3 million years ago
That was during the Mid-Pliocene Warm Period.
Source: NOAA Climate.gov (2025) climate.gov
Expert level
How much did global average atmospheric CO2 rise in 2024 alone?
Answer3.75 ppm
It was the largest one-year increase on record. The recent rate of increase is 100–200 times faster than natural rises at the end of the last ice age.
Source: NOAA Climate.gov (2024) climate.gov
What were total U.S. greenhouse gas emissions in 2022, in CO2 equivalent?
Answer6,343 million metric tons CO2 equivalent
This total excludes the land sector. Transportation is the largest direct source of U.S. emissions.
Source: U.S. Environmental Protection Agency, Sources of Greenhouse Gas Emissions (2022) epa.gov
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