EXPLAINED IN 70 SECONDS
WHAT IT IS
Carbon dioxide (CO2) has been on the rise in the atmosphere since the Industrial Revolution. It has been measurement continuously since the late 1950s at Mauna Loa Observatory in Hawaii and those measurements are the basis for the Keeling Curve, one of the most iconic images in climate science. CO2 concentrations are measured in parts per million, or ppm. Since the first measurements in 1958, CO2 has risen from 313 ppm to over 400 ppm. Using other techniques, scientists can see that CO2 was around 280 ppm at the start of the Industrial Revolution. A large part of the increase comes from human activities, especially from the burning of fossil fuels like coal, oil and natural gas. Other observations around the globe support the observations being taken at Mauna Loa.
WHY IT'S IMPORTANT
Carbon dioxide is the primary greenhouse gas driving climate change. It recently surpassed a reading of 400 ppm in the atmosphere for the first time in human history. Scientists estimate that the last time CO2 levels were that high was more than 3 million years ago, when the Arctic was 32°F warmer than it is today and sea levels were up to 90 feet higher. The climate responds slowly to changes in CO2 levels, so even if all carbon emissions stopped today, global temperatures would keep rising and other climate impacts would continue to be felt for decades or centuries to come.