Carbon dioxide (CO2) is a naturally occurring gas, vital to life on Earth, but it’s also a major player in climate change. It’s known as a greenhouse gas because it traps heat in the Earth’s atmosphere, much like the glass roof of a greenhouse. While CO2 comes from natural sources, human activities are significantly increasing its concentration in the atmosphere, leading to global warming.
CO2 is released through natural processes like volcanic eruptions and animal respiration. However, the burning of fossil fuels—coal, oil, and natural gas—for energy, alongside deforestation and industrial processes, has dramatically increased atmospheric CO2 levels. Measurements taken at NOAA’s Mauna Loa Observatory in Hawaii since 1958 provide a clear picture of this rise. Looking further back, ice core data reveals CO2 concentrations over hundreds of thousands of years, showing a sharp increase since the Industrial Revolution in the 18th century.
This increase is substantial. Atmospheric CO2 has risen by 50% since 1750, reaching levels not seen in hundreds of thousands of years. This rapid increase, driven by human emissions, is far greater than natural fluctuations observed in the past, such as the changes at the end of ice ages. The current CO2 concentration is over 420 parts per million (ppm), a significant jump from around 365 ppm just two decades ago. Parts per million refers to the number of CO2 molecules per million molecules of dry air, indicating how much CO2 is present in the atmosphere.
Interestingly, CO2 levels also fluctuate seasonally. Each year, measurements at Mauna Loa show a “wiggle” pattern. This is due to the Earth ‘breathing’. During spring and summer in the Northern Hemisphere, plant growth surges, and plants absorb CO2 from the atmosphere through photosynthesis. This process lowers atmospheric CO2 levels. In autumn and winter, plant growth slows down, and decomposition releases CO2 back into the atmosphere, increasing levels again. While this seasonal cycle causes short-term ups and downs, the overall trend is a consistent and concerning upward climb in atmospheric CO2 due to human emissions.
In summary, carbon dioxide is a critical greenhouse gas. While natural processes contribute to CO2 levels, human activities, particularly the burning of fossil fuels, are the primary driver of the alarming increase in atmospheric CO2. This increase is the major cause of global warming and climate change, making it crucial to understand and address our CO2 emissions.
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