Did you know CO2 is naturally higher in the winter? During the spring and summer, plants use CO2 from the atmosphere to grow. Over the winter, plants decompose and release CO2 back to the atmosphere. But from year to year, CO2 continues to increase. The overall upward trend is due to increasing carbon emissions, primarily from burning fossil fuels. So the annual cycle is from plants while the long-term trend is caused by human activities. Video Description: A line graph on a white background showing the amount of carbon dioxide in the atmosphere every month since 2013. The graph is titled, How does CO2 change throughout the seasons? The line showing the amount of CO2 over time is sawtooth-shaped, with a peak each spring and a valley each autumn. In addition to that annual wiggle, the overall amount of CO2 increases every year. So the line looks like a jagged, upward slope. Text on the graph walks through the explanation: The upward trend in carbon dioxide in the atmosphere is caused by carbon emissions. The primary cause of human carbon emissions is burning fossil fuels. But what causes the sawtooth, up and down pattern? Plants! During the growing season, plants draw in CO2 to fuel their growth. In the autumn, CO2 reaches its lowest point for the year. As plant growth stops or slows down, the whole process reverses itself. Plant matter decomposes and releases CO2 back to the atmosphere. CO2 increases throughout the winter months. Hitting its annual peak in springtime. Then the cycle repeats, as plants start growing again and using up CO2. So while nature causes the sawtooth pattern of ups and downs from year to year, humans are causing the upward climb of the trend line over the years. Thus, the data illustrate both natural factors and human additions of CO2. #NASA #Earthscience #ClimateChange #Carbon