Final answer:
Carbon dioxide (CO₂) is the most responsible element for global warming.
Step-by-step explanation:
The element most responsible for global warming is Carbon dioxide (CO₂).
Carbon dioxide, along with methane and nitrous oxide, has a high concentration in the atmosphere compared to synthetic gases, making them responsible for most of the human-caused global climate change.
Human activities, such as burning of fossil fuels and changes in land use, release large amounts of CO2 into the atmosphere, causing its concentration to rise and contribute to global warming.