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How did atmospheric carbon dioxide levels change between the beginning of the Industrial Revolution and the early 21st century?

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World map shaded to show annual carbon dioxide emissions by country in 2022, with China, the United States, and India highlighted as top emitters in dark red. A bar chart below lists the top ten emitting countries by million metric tons. — Greenhouse gas Map of annual carbon dioxide emissions by country in 2014.

At the beginning of the Industrial Revolution, the natural background level of atmospheric carbon dioxide (CO₂) was approximately 280 parts per million (ppm).12

Since that time, human activities—primarily the burning of fossil fuels and land-use changes—have caused a steady and significant increase in these concentrations. By the early 21st century, atmospheric CO₂ levels had reached 384 ppm, representing an increase of approximately 37 percent above preindustrial levels. This upward trend has continued, with measurements reaching 410 ppm by 2018 and 419 ppm by 2022.132

These concentrations are believed to be the highest in at least 800,000 years, and potentially the highest in 5,000,000 years. This accumulation of greenhouse gases is a primary driver of global warming, as these gases enhance the atmosphere's ability to retain heat.124