Carbon dioxide (CO2) is a naturally occurring chemical compound and a vital greenhouse gas in Earth’s atmosphere. Understanding “Carbon Dioxide What Is” is crucial because of its significant role in trapping heat and influencing our planet’s climate. Human activities have dramatically increased atmospheric CO2 levels, leading to global warming and climate change. In fact, the amount of carbon dioxide in the atmosphere today is about 50% higher than it was before the Industrial Revolution.
What exactly is carbon dioxide, and why is its increasing concentration a cause for concern?
Carbon dioxide, chemically represented as CO2, is a molecule composed of one carbon atom and two oxygen atoms. It is a colorless and odorless gas that is a natural part of Earth’s atmosphere. CO2 is released through natural processes such as volcanic eruptions, respiration of living organisms, and wildfires. However, the primary driver of the recent surge in atmospheric carbon dioxide is the burning of fossil fuels – coal, oil, and natural gas – for energy, alongside deforestation and industrial processes. These are considered anthropogenic, or human-caused, sources.
Carbon dioxide is a greenhouse gas, meaning it absorbs and re-emits infrared radiation (heat) from the sun that would otherwise escape back into space. This process, known as the greenhouse effect, naturally warms the Earth and makes it habitable. However, an increased concentration of greenhouse gases like CO2 traps more heat, leading to a warming planet.
Scientists at the Mauna Loa Observatory in Hawaii have been meticulously measuring atmospheric CO2 levels since 1958. These measurements, taken by NOAA (National Oceanic and Atmospheric Administration), provide a continuous record of the increasing concentration of CO2 in our atmosphere. The latest data from January 2025 shows an annual average anomaly of 427 parts per million (ppm). Parts per million is a unit used to measure the concentration of a substance, in this case, indicating that there are 427 molecules of carbon dioxide for every million molecules of dry air.
To understand the historical context, ice core data reveals CO2 levels over hundreds of thousands of years, capturing air bubbles trapped in ancient ice. This data shows that CO2 levels remained relatively stable for millennia before the Industrial Revolution. The current rapid increase is unprecedented in at least the last 800,000 years and is directly linked to human emissions. This dramatic rise in atmospheric CO2 is the key driver of global warming, leading to a cascade of climate change impacts, including rising global temperatures, melting glaciers and ice sheets, sea level rise, and more frequent and intense extreme weather events.
Looking closely at the Mauna Loa CO2 measurements reveals an interesting seasonal cycle. While the overall trend shows a steady upward climb, there are also yearly “wiggles” in the data. This seasonal fluctuation is due to the Earth’s “breathing” – the massive seasonal cycle of plant growth, particularly in the Northern Hemisphere. During spring and summer, as plants grow and undergo photosynthesis, they absorb significant amounts of CO2 from the atmosphere. This process lowers atmospheric CO2 levels. In autumn and winter, when plant growth slows or stops and vegetation decays, CO2 is released back into the atmosphere through respiration and decomposition, causing CO2 levels to rise again. This creates the sawtooth pattern observed in the CO2 record.
You can explore an animation of this seasonal cycle in the visualization “Watching Earth Breathe: The Seasonal Vegetation Cycle and Atmospheric Carbon Dioxide.”
To delve deeper into why carbon is important, you can visit NASA’s Climate Kids: Why is Carbon Important?.
NASA also operates several missions dedicated to observing and studying carbon dioxide in the atmosphere, providing crucial data for climate research:
- Atmospheric Infrared Sounder (AIRS)
- Orbiting Carbon Observatory (OCO-2)
- Orbiting Carbon Observatory (OCO-3)
In conclusion, understanding “carbon dioxide what is” and its behavior in the atmosphere is fundamental to grasping the complexities of climate change. Carbon dioxide is a potent greenhouse gas, and its escalating concentration due to human activities is unequivocally driving global warming. Continuous monitoring and further research, like that conducted by NASA and NOAA, are essential to inform climate action and mitigate the impacts of rising CO2 levels.
