Discover how atmospheric CO2 has increased during your lifetime
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Your "CO2 age" represents how much atmospheric carbon dioxide has increased during your lifetime. This metric helps put climate change into personal perspective by contextualizing the rapid global CO2 increase that has occurred during your lifetime.
When you were born, the atmosphere contained a specific concentration of CO2, measured in parts per million (ppm). Since then, human activities - primarily fossil fuel burning - have added more and more CO2 to the atmosphere. Your CO2 age represents the total increase in CO2 concentration that has occurred during your lifetime, providing a personal reference point to the global CO2 increase you've witnessed.
This increase isn't just a number - it represents a fundamental shift in our planet's atmospheric composition that affects global temperatures, weather patterns, precipitation, global ecosystems, and even human health. By understanding your personal CO2 age, you can better appreciate the scale and rate at which atmospheric CO2 has increased in your few short years on Earth.
🌎 CO2 age is not a one-to-one function — you may share the same CO2 age as someone born in a different year, uniting us across generations in our shared climate-CO2 trajectory. Due to the seasonal fluctuations in atmospheric CO2, people born months or even years apart can have similar CO2 ages.
The Keeling Curve shows a distinctive sinusoidal or "sawtooth" pattern with regular peaks and troughs each year, on top of a steadily increasing baseline. This seasonal cycle is driven by the annual cycle in plant respiration in the Northern Hemisphere, where most of Earth's terrestrial biomass is located.
Spring and Summer (CO2 decreases): As plants photosynthesize and grow, they absorb large amounts of CO2 from the atmosphere and convert it into organic biomass. This natural process temporarily reduces atmospheric CO2 concentrations, leading to the annual minimum typically observed in late summer.
Fall and Winter (CO2 increases): When plants decompose and respire, or when they reduce photosynthesis during winter months, plant respiration and microbial decomposition release stored carbon back to the atmosphere as CO2. This leads to the annual maximum typically observed in late winter or early spring.
The seasonal amplitude of this natural "Earth breathing" cycle has been increasing over recent decades as atmospheric CO2 levels rise and plant growing seasons change due to climate change. This expanding range demonstrates how Earth's ecosystems are responding to our changing atmosphere.
The Keeling Curve is a graph of the annual variation and overall accumulation of carbon dioxide in Earth's atmosphere based on continuous measurements taken at the Mauna Loa Observatory in Hawaii from 1958 to the present day.
The curve is named after scientist Dr. Charles David Keeling, who started the atmospheric monitoring program and supervised it until his death in 2005. The program has been continued under the leadership of Dr. Charles Keeling's son, Dr. Ralph F. Keeling with support from the U.S. National Science Foundation and National Oceanic and Atmospheric Administration. Keeling's measurements showed the first significant evidence of rapidly increasing carbon dioxide (CO2) levels in the atmosphere. Many scientists credit the Keeling curve with first bringing the world's attention to the current increase of CO2 in the atmosphere.
Today's atmospheric CO2 measurements come from two primary sources working in parallel:
NOAA Global Monitoring Laboratory: NOAA GML conducts research on greenhouse gas and carbon cycle feedbacks, changes in aerosols, and surface radiation, and recovery of stratospheric ozone. Their Mauna Loa CO2 measurements provide the official reference data used by climate scientists worldwide.
Scripps Institution of Oceanography: The original Keeling program continues under Ralph Keeling's direction, providing independent verification and additional scientific analysis of atmospheric CO2 trends and seasonal patterns.
Mauna Loa was chosen as a long-term monitoring site due to its remote location, isolation from anthropogenic activities, and its lack of vegetation.
The measurements collected at Mauna Loa Observatory show a steady increase in mean atmospheric CO2 concentration from 313 ppm in March 1958 to 428 ppm in July 2025. The amount of carbon dioxide in the atmosphere has risen more than 50 percent since humans began burning fossil fuels for energy.
For the most up-to-date CO2 measurements, scientific analyses, and comprehensive historical data, visit:
These sites provide real-time data updates, research publications, and additional educational resources about atmospheric CO2 monitoring.