The atmosphere currently contains about 425 parts per million (ppm) of carbon dioxide, based on recent global measurements. A 2025 World Meteorological Organization report put the 2024 global average at 423.9 ppm , and later reports in 2025 showed values above 430 ppm in May 2025.

Quick Scoop

  • Pre-industrial CO2 was about 280 ppm.
  • Recent readings are in the 420s to 430s ppm range.
  • The exact number changes through the year and depends on whether you’re looking at a monthly, yearly, or daily average.

What that means

That level is historically very high, and it is one reason scientists say human activity is driving current warming. The main source is burning fossil fuels, along with land-use change and industrial emissions.

In plain language

If you just want the short answer: roughly 425 ppm today. That’s a little over 0.04 percent of the atmosphere, but it has a strong effect on heat trapping.

TL;DR: CO2 in the atmosphere is around 425 ppm , with recent measurements crossing 430 ppm in 2025.