The Science of CO₂
Carbon dioxide (CO₂) is one of the most talked-about gases on Earth — and for good reason. It’s invisible, odorless, and naturally occurring, but when present in excess, it becomes a driving force behind global climate change. To take meaningful action, we must first understand the science behind CO₂: where it comes from, how it behaves in the atmosphere, and why it matters.
What Is CO₂?
CO₂ is a colorless gas made up of one carbon atom and two oxygen atoms. It’s essential to life: humans and animals exhale CO₂ during respiration, and plants absorb it during photosynthesis to produce oxygen. But as human activity has rapidly increased CO₂ emissions over the last century, its delicate balance in our atmosphere has been disrupted.
The Greenhouse Effect Explained
CO₂ is classified as a greenhouse gas because it traps heat in Earth’s atmosphere. When sunlight reaches Earth, some of it is absorbed by the surface and re-radiated as infrared heat. Greenhouse gases like CO₂ absorb this heat and re-emit it in all directions — including back toward Earth. This is called the greenhouse effect, and while it’s a natural process that keeps our planet warm enough for life, too much CO₂ means too much trapped heat.
Since the industrial revolution, atmospheric CO₂ levels have skyrocketed. In 1750, global CO₂ levels were about 280 parts per million (ppm). Today, they exceed 420 ppm — a concentration never before experienced in human history.
Where Does CO₂ Come From?
The primary sources of human-caused CO₂ emissions include:
- Burning fossil fuels (coal, oil, and natural gas)
- Deforestation and land-use change
- Cement production and industrial processes
Transportation, electricity generation, and agriculture are three of the largest contributors globally. Every time we drive a gasoline-powered car, charge a phone from a coal-powered grid, or fly on an airplane — CO₂ is released into the atmosphere.
Tracking and Measuring CO₂
Scientists use a variety of methods to measure CO₂ levels, both locally and globally. The Mauna Loa Observatory in Hawaii has been monitoring atmospheric CO₂ since 1958, producing the famous "Keeling Curve" — a dramatic graph that shows the relentless climb of CO₂ concentrations over time.
Satellites, ocean buoys, and air sampling networks now provide a much clearer picture of how emissions vary across regions and seasons. These measurements are critical for climate modeling and for verifying emissions data submitted by countries under international agreements.
Why It Matters
Understanding the science of CO₂ helps us recognize the urgency of the climate crisis. This isn't just about melting glaciers or rising sea levels — excess CO₂ leads to stronger storms, more wildfires, declining air quality, and health risks. It disrupts ecosystems, agriculture, and even global economies.
But knowledge is power. The more we understand about CO₂, the better equipped we are to reduce our emissions, advocate for policy change, and shift toward renewable energy.
Take Action Today
At CarbonTracker.io, we’re committed to helping you understand and reduce your carbon footprint. Start with our carbon calculator, explore our guides, and share this knowledge with your community. The science is clear — and your actions matter.