Pure speculation. There is nothing that supports that.
Sigh. Never tell me there is no support for something that I know something about.
What does the lag of CO2 behind temperature in ice cores tell us about global warming?
Water Vapour, CO2 and Insolation over the Last Glacial-Interglacial Cycles
Feedback Loops in Global Climate Change Point to a Very Hot 21st Century
What Caused Glacial-Interglacial CO2 change? (This is a Powerpoint presentation, so good that I saved it after Google found it for me).
Ice-driven CO2 feedback on ice volume
CO2 Lags, Not Leads (countering a common skeptical argument)