If the heat capacity of CO2 does not significantly change between 200 ppm (parts per million) and 400 ppm, it suggests that the concentration of CO2 alone does not have a significant impact on its heat capacity.
Heat capacity is a measure of how much heat energy is required to raise the temperature of a substance. If the heat capacity remains relatively constant despite the change in CO2 concentration, it implies that the thermal properties of CO2 itself are not significantly affected by variations in concentration within this range.
However, it's important to note that while the heat capacity of CO2 may not change, the increase in CO2 concentration from 200 ppm to 400 ppm is significant in terms of its impact on the Earth's climate. This increase is associated with the greenhouse effect and the potential for global warming. The concentration of CO2 in the atmosphere affects the overall radiative balance and energy absorption, which can lead to changes in Earth's temperature.
Therefore, while the statement suggests that the heat capacity of CO2 does not significantly change within this range, it does not negate the broader implications of increasing CO2 concentrations on climate change and the potential consequences associated with it.