Final answer:
The amount of CO2 in the atmosphere is higher than it has ever been for the last 800,000 years.
Step-by-step explanation:
Yes, the statement is true. Reliable data from ice cores reveals that the level of CO2 concentration in the atmosphere is at the highest it has been in the past 800,000 years. In recent years, the concentration of CO2 has increased from preindustrial levels of -280 ppm to more than 400 ppm today. This increase in CO2 concentration is mainly caused by human activities, particularly the burning of fossil fuels.