The current value of carbon dioxide in the atmosphere is:

The current value of carbon dioxide in the atmosphere is indeed higher than it has been for the last 800,000 years. This conclusion is based on extensive ice core data, which allow scientists to examine historical carbon dioxide levels by analyzing trapped air bubbles in ice. These records indicate that atmospheric CO2 levels fluctuated naturally through glacial and interglacial periods, typically ranging from about 180 to 300 parts per million (ppm) over the last 800,000 years. Current measurements show that CO2 levels have exceeded 400 ppm due to human activities, particularly the burning of fossil fuels and deforestation. This significant increase represents a dramatic departure from natural variability over that extensive time scale and is a primary contributor to modern climate change.

In contrast, options that suggest CO2 levels are similar to those in previous climatic eras fail to take into account this unprecedented rise attributable to human influence. The levels seen during the last interglacial period and the last ice age were much lower than today, highlighting the distinctiveness of the current situation.